I believe the fuse is for when the battery is shorted, and only for that reason. if the battery gets physically gets damaged externally, or if the battery internally is damaged from overcharging maybe, it may short out. the current from the complete battery pack would try to travel through the shorted battery. If a fuse is installed it will blow and then will disconnect the shorted battery from the pack. The battery you are testing on the bench is not shorted. it may be discharged and hold nearly no charge anymore. but it is definitely not short. if it was, it would have burned the fuse wire immediately.
Agree, the fuse is there to prevent a explosion once the battery is shorted. This may occur when the internal insulation get punctured (use of time, overload, physical damage). Personally I'm using those for my current project: www.ebay.com/itm/100pcs-Glass-Tube-Fuse-Axial-Leads-3-6-x-10mm-6-3A-6-3Amps-F6-3A-Fast-Quick-Blow/290945050705?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
One could make the same argument over fusing in a motor vehicle or even a house. There is a distinct possibility that you may never trigger a fuse over the lifetime of a system. But, do you really want to gamble with your family's safety? Even the improbable is possible.
It could. But short circuited cells are extremely rare. It's more common that the internal protection of the cell kicks in and disconnects the cell from its casing, rendering it useless but preventing a dead short and eventually, the infamous lithium fire!
I had a battery that shorted in my custom built ebike battery without fuses and it drained the entire parallel cell of about 15 batteries right down to zero and the entire row was absolutely piping red hot. None of the batteries could be revived. Had to rip out the entire row and rebuild it with 15 replacements. Definitely looking into getting fuses now.
It is quite a bit harder on eBikes because of the way they are treated ie. bouncing around i think our style fuses will break just through micro movements over time. let me know how you go and what path you end up taking
If you are using significant power, those fuses are going to be horrible for an ebike. I am using cells rated for 20 amps continuous, and I also absolutely do not want unnecessary voltage sag under load. So that means with a 21s12p pack, I want to be able to pull upwards of 100-180A continuous if desired without overheating the pack, blowing fuse links, or having a ton of internal resistance buildup in the battery. I have ordered a full BMS so there is a degree of protection (only output isolation, not internal). I also built a resistance welder, so that I don't roast the batteries trying to solder to them. I will be cautious with the pack for a while until it proves to be stable, but internal fuses just isn't an option. I'm fairly sure a dead short would probably roast the weld points in the cell that is shorted.
TheFootbaldd And obviously tesla cars have a fuse on every cell which pull way more power and bounce around more than any ebike. Completely open to suggestions here. Just want to produce the best battery I can that will last the mileage. Thanks
There is a significant difference between a highly engineered pack like the flat packs Tesla uses and an e-bike. The mechanical agitation in one of their packs should be significantly less than in a cycle for obvious reasons. There are many fail-safes designed into modern non clone 18650s to prevent runaway conditions. Could you show some documentation on your isssue with pictures of the build and the failure?
hey punch a screwdriver through a cell or crush it in a vice and see if it get an internal short. Then see how many amps it draws i think that part of the reason why the fuses are there... ?
It depends on the quality of the batteries. Batteries with high internal resistance will not be able to produce high currents. So, the often detested Chinese quality can actually be safer :-) Their capacity though is too low for serious use.
Looks like your long fuse wire is just acting like a resistor. Remember, ohms = MALT (material, amperage, length, & temp). To replicate it, use a short section of fuse wire.
Fuses serve one function, to conduct current through a circuit and then melt immediately if more current flow than their rated maximum limit goes through them. They are used to prevent dangerous overloading in a circuit and that's basically it. There are some"tricky" uses for fuses but the reason to fuse every single battery in an array like that is to automatically isolate one single cell from the rest of the array should an internal short failure occur in one of them. In cell arrays with high numbers of cells in parallel, a dangerous amount of current will be able to flow from the other cells in to the shorted one which may lead to a thermal cascade that results in failure of that bank of cells and possibly a dangerous fire/explosion. Having a "dead" battery in parallel with many fully charged batteries will cause an unregulated amount of current to flow in to the low voltage cell as the charge naturally balances out. It usually isn't going to result in a catastrophic failure but it unbalances your battery pack and stresses the bad cells even more.
When running these batteries in vehicles, depending on the number of cells you have in parallel, the idea is to prevent current surges through a single battery. Some controllers can pull up to 650 amps. Well running 3.7 volts from 1 battery at 1 amp, the single battery is going to have to give off the whole amp alone. If 2 batteries are in parallel, then it will only require 0.5 amps from each to make up the 1 amp. Going back to the 650 amps, 650 cells would need to afford 1 amp a piece. Cut the number of cells in 2 to 350, each cell climbs to 2 amps. If a battery is bad chances are it will try to discharge at a higher rate than the others (a short) causing the fuse to blow before the battery heats to a point at which the contents literally start to boil.
Ahh, i see, it's primarily to protect the cells from discharging above the designer intend. Hence it's a very simple over-discharge contraption. But how it is correlate to the battery that in dying condition? i've looked around but i can't seems to find a way or system that can read individual cell's health when use in power pack such as power wall.
If cells are in parallel, it is difficult to determine the health of an individual cell, as the other cells will cover up for it. So you will have to look at the group of parallel cells, and compare it to other groups with the same number of cells. If the group charges too fast, or too slow, compared to others, then most likely one of the cells in the group has an issue. This has to be resolved because even if the BMS catches this anomaly, it will cause a good part of your energy storage to be wasted, until you replace the cell. If the BMS does not catch it, then that can turn into a safety issue.
hy, i build a 48v pack. and i fuse every cell with a resettable fuse with are rated at 3a. so if my motor try to take more then 3a from my pack it wil disconect, and reconect when the amps get down again. sorry for my bad english
I agree with BillTheBox - the fuses protect against a rare single cell shorting internally - in which case there will be a rise in current. And if the short is bad enough the current will rise enough to blow the fuse. My working assumption is that this type of fault is more likely in an electric car situation where the battery is being stressed. Jahu mentions in one of his vids that he found blown fuses in his recycled battery packs after using them in the Samba. I suspect that's why he switched to using real Tesla packs. For a Powerwall we are looking at much lower max current demands so the chances of a battery short are likely to be less. But, again - that's just my hunch. I think the main benefit of the fuse system is it's an easy way to solder the batteries with just a soldering iron. I think it's the best DIY process for connecting cells up.
+Paul Kennett I've only just managed to disprove my own thoughts - but missed the moment when i panicked and launched the battery into the old pool area (we are digging out our pool) i'll try to edit together what i have and voice over the rest - Found one cell that was at 56deg 13min after removing it from the charger
+HBPowerwall I've had only one over heating cell, that I've noticed, since I've started doing this - probably 1000-ish cells. I assumed it was because my iMax clone was over-charging (which it was) - so bought my iCharger for charging. Maybe it would have overheated on the iCharger too. Freaky though. Sounds like you had a close call.
As somebody already pointed out these fuses help only when cell is shorted out or whole pack load is so high that amperage load for particular cell is higher than fuse can keep. Now, it will not and it should not blow fuse if some cell just worse than others, has internal open circuit, or has internal resistance higher than others. More, just imagine that your pack voltage is 4V and you connect some cell charged up to 2V. Let say that you have 5A fuse. To blow that fuse your cell have to have resistance less than (4-2)/5 = 0.4 Ohm. If your cell is not new that its internal resistance can be higher than that. To make things more complicated, when you connect that cell to the pack it' voltage will increase pretty fast especially if cell is not so good. So current will be even less and not enough to blow the fuse. So, just leave the fuses alone, they will do the work WHEN ACTUALLY NEEDED. Try to apply Ohm law and you will be amazed how it easy to explain a lot of things. Thank s for your great videos. I like your curiosity and wish you the best.
fuses are for when you get a puncture ( eg you drop the pack ) or when you short both poles ( you should have a master fuse for that ) But the point isn't that it will help every time, you just want to be saved that one time when there is a short in one battery that happens to have developped a low resistance short, and even if that is only a 1/1000 chance I would still do the fuses. ( low resistance means a lot of current can pass through the battery ) But that's me, I blow myself up and burn myself pretty often so safety precautions are key for me Also I don't think you understand completly how the batteries die and what shorting is/why people don't use batteries that where under 1 or 0.5 volts. -> in a lithium battery you are taking advantage of "reversible" reactions,they can go both ways ( discharge and charge ) -> when you go under 3v then the reaction goes on to a further stage that IS NOT reversible ( at least not without dumping a massive voltage to the poles ) this 'deposit' of conductive material on one of the poles will sometimes manage to make contact ( via the walls of the battery or other ) with both poles, effectively "shorting" the battery -> because that short is, as I said, a small deposit, it is generally a high resistance short ( battery self discharges and doesn't take a charge without warming up ) I can clarify if needed, I don't know if I explained that correctly
+BillTheBox I get it, just want to see it, does that make sense? I'm still doing it and i'm happy to eat my words when they save my ass/house/shed/car/boat/bikes etc :)
+BillTheBox Yup.. the gap between + and - terminal in this 18650 single cell is only about 3mm..without the protection cap and heat shrink plastic you easy can short this terminal in case of carelessness or traumatized to produce over current and create heat resistance causing cell leakage, burst or even fire and start the chain reaction to the other cells in this big module..
Like any fuse there is a fuse curve of current vs time. So the fuse will never blow at it's rated current, 10x rated current it will open in minutes, 100x rated current in seconds, 1000x rated current 0.1 sec, etc. Or something like that. The fuse curve is usually on a log scale. So the fuse will protect against a real fault or a low resistance high current fault in one battery.
Best is subjective - and would be considered when money was no object - in the desert of Africa where they don't even own a soldering iron the BEST has a different meaning. Best part about these projects are their scalability
I used 2 matched cells recovered from a laptop for a 2S battery in a holder, and had one cell spontaneously go bad, short, idk, but begin smoking as I walked past it in my living room. I’ve made a bunch of batteries over the past few years and that’s the only time it’s happened. Now I mostly use 18650s in an esp8266 battery charger, and will be building lifepo4 packs for 12v.
Fusing every cell in a parallel battery pack is critical to my personal safety, and when I build large packs I will fuse them in some way. I am more concerned that people are using, in effect, random wire, not wire intended to blow at a specific amperage, and to blow in a "clean" way without a lot of metal flying around. For me, I'd rather experiment with fuses, measure the voltage drop across them, and the heat they produce from that drop. From there, perhaps finding the kind of wire they use would work. Also remember a lot of things will affect wire fusing: the solder itself acts as a big heat sink, so there is a minimum distance from the solder joint where the fusing will occur. The fuse wire will drop more voltage than a larger wire, so there is loss due to heat across each wire (even if it's not warm, there is a drop, and it will vary by amps). Also, a "slow death" of a cell where it is drawing near to but not over the fusing level will just make a localized heater, which may itself cause a fire. There's a reason fuses are in little glass tubes.
What is the load that you are connected to? I think the problem with what you're trying to do is the resistance internal of the dead battery versus the resistance of the pack. The dead battery has a higher resistance meaning when connected to a load the total resistance will be higher and depending on the load the pack will heat up more quickly or not deliver the rated power at the efficiency that it was designed for. I guess I was wondering what test conditions you have setup, still don't know the load that is connected to?
Well you know my view from the start on fusing each cell, the fuse is to protect the wire/cable .the only way imho that the fuses will ever blow is if the main +&- busbar are shorted out and if it was me I would fuse each busbar
Is the fuse wire only needed because you are paralleling all 150 batteries on the same bus? What if you soldered 14 in a series, and then only doubled in parallel? Then the Volts would be high (say 48v), but the amps would be low (say 8-10A). Would you need it on that? Would it even be possible to short the batteries in series, or would you have to short every battery in that series? If keeping the parallel to only 2 would prevent you from needing to fuse each cell, would you then need to fuse each pack if you then paralleled 100 of those on the same bus (one fuse per pack/28 batteries)? What is the advantages of high amp and low volts, vs high volts, low amps?
i've thought about this myself. I'm thinking for stationary energy storage/low peak draw; I would maybe have fuse wire that pops very close to the expected max draw. Like so close you have false positives also test with a same length that is in the pack.
So how do you deal with a single 18560 that has an internal short and shorts itself out and heats up to the point of flame and pop? An internal short is not pushing or pulling current so can't blow a fuse. No current across the fuse equals no blown fuse. But you could still get a fire.
If only one cell blows the damage will not be tremendous. If the rest of your cells are shorted because of this one cell the damage might get much bigger. Not even a protected cell is prevented from the situation you are describing. You could build a thick wall iron case around each cell :-)
Some commenters have the wrong idea ... we're discussing fusing ALL cells , which seems ridiculous to me ....in the video, the longer the dead cell was connected to the pack the less current it took ... the problem to avoid is a dead cell slowly draining the pack at half an amp or so ...a fuse won't stop that ! The solution must be to have large blocks of cells in parallel , put these in series to get the voltage required , then when in use check the voltage of each component pack once a month ... if one pack is low look at the base of the cells with a thermometer , to see which cell is draining the pack.
Individual cell fuses have been now proven to be required (by me) 4-5 cells dead short blew the fuses nothing happened. UNTIL I pulled the pack and noticed blown fuses - retested and wow, no thank you .. Fuse both ends not just the positive side
You maybe correct ... I don't have enough understanding about how these cells go bad ... But for sure there's no need to have a fuse on both ends ... and make sure you use real fuse wire (alloy of lead and tin) copper wire or galvanised is not suitable , many reasons( I can elaborate if you like) ...www.answers.com/Q/What_is_the_Composition_of_fuse_wire
I've been looking a lot into fuses over the past week, and have revised my opinion a little ... I believe tinned copper is OK as long as red hot blobs of molten copper are not a problem on the rare occasion one blows , lead tin fuses will melt at 300C , so only warm molten metal flying about ...I've just ordered some 31AWG tinned copper wire for use as fuse on these cells . There's still a lot to learn about the way these cells fail I don't believe they can completely short , just fail in a way their internal resistance and self discharge goes too high and they drain the pack ....and this will eventually blow a fuse. If anyone does have a cell which blew a fuse when in a pack examine it carefully for voltage int resistance , will it still hold some charge? This will teach us a lot.
fuse all the cells connected in parallel, don't fuse any connected in series, that would be pointless, just add a fuse at the output, if it makes sense, it might not for your application
cells have a ptc and cid and will limit there own current and pressure. However, when in series above 30v, a PTC can char and CID can arc in high current situations. This may be the reason tesla use fuses. The PTC research was conducted by nasa & CID by clermonte university
I had a LiFePo4 battery get shorted once (due to me dropping the pack on concrete). I had no fuses or fuse wires, and the cell made a direct short. The cell got blazing hot and drained the 3 cells in the pack in a matter of a minute or two. I'm sure that was over 10A shorted, and if i had just used fuse wires or slo-blow minis, this would not have damaged the other cells! Of course, had this been a Lipo or LiCoMXXX or whatever other chemistry it certainly would have lit up, possibly destroying the pack as well as my equipment!
It just seems like overcurrent protection for individual cells instead of for entire pack. Not sure how much it would help since cells are unable to drift in voltage when connected so significant current flow should not happen. Tho fusing like you do with wire seems to be a weak point and get damaged when instaling/moving the pack
The way I see it is that if one cell has a fault on it it may start off as a small fault with the cell but as time goes on the fault will only get worse and not better until it gets bad enough to short totally, The cell is encased in metal so any problems at the positive end may short out to the case negative and the next thing you know is all those battery's in parallel are feeding into this new path of least resistance. Most faults occur over time especially major ones, those faulty cells you tested probably had a BMS attached to them so they shut down pretty quickly before any real problems occurred like fire or explosions. I soppose it all depends on what type of fault is wrong with the cell, chemical or the way it was manufactured
I don't bother most of the time with fuses on the pack and never use fuse wire on the individual cells unless it's a really large, high voltage one. Generally I will use a nickel strip that can handle the current I'm aiming to draw through it and that will fail when the current goes too far above that. But again, for high amperage packs, I will use an inline fuse just after the pack and before the BMS as the fuses I use act faster than the BMS' own OCP. Generally in the realm of about 30 amps is good for the ones I build if they need to be fused. For cells that fail in a pack, I have only really encountered cells that refuse to accept a charge or that act like a massive resistor, sapping away current and getting warm but haven't had one fail dead-short and catch fire. Probably because I am extremely careful with charging and discharging my lithium cells. I only use dedicated Lithium chargers and will always referring to the datasheet for my specific cells to ensure that I am not cramming excessive current into them during charging.
So what you have done with putting the cells in parallel is nothing more than what is done with the large Prismatic style cells that use flat leaves all stacked in parallel within the cell. So each of those 18650 cells is like a single leaf within the large flat packs. So I'd say its just along for the ride. Will you even get one of those to short out within the paralleled pack? Not so sure you would. I'd like to see it actually happen. Might just be a very rare event. One in which there is little to worry about. Jehu has driven his in his Bus for some time now and they are all fine and he built his out of mismatched to a point. You may have one weak one in the bunch but it may not be a problem as they are all pretty much sharing the load. Unlike those in series. If you have a bunch in series you could cause a cell to go. This is why I just use prismatic and bottom balance. If I have a cell so far out of whack from the others I just replace that cell. I can't go in and replace a leaf within the prismatic cell. Those leaves within a prismatic are not fused. Why would you then fuse the 18650 cells you put in parallel?
its to protect from a rare chain reaction : i read about Li Ion chemistry, that especially while dischared or more precise while lower than minimal rated charge level (empty) , the cells "can" build up metal crystals within the chemistry of the cell over time. not just reducing capacity, but it can lead to internal short circuit (or at least low R somehow). Now if such a cell would go bad like that in a battery with many parallel connected cells, there could be a giant short circuit current, even if all the parallel cells are supposed to be "low" or "empty" (on li ion they are never really "empty" , you know) . And so that could cause a chain reaction of events. cells and cabeling then overheat and go haywire, not unlikely to catch fire. THAT is what these cell fuses are supposed to protect you from. If one cell goes short circuit, its fuse will blow, since all the parallel cells together will pump more current into it than its single fuse can handle. its not guaranteeing that the whole thing wont catch fire, but a single cell may be easier to handle or safely isolate from the others, hopefully not resulting in some chain reaction.
these cell fuses are NOT really about balancing. just protecting each cell from massive overcurrent , either while charging but more likely while discharging or just being connected in a battery with others.
Fusing high current batteries is a safety option - should one short it will prevent a fire. If one shorts and you have a number of banks in series, you will have a fire quicker that you can blink as the other series batteries will over-charge in the bank and teh parallel ones will short maybe creating an explosion. Determining faulty cells will need to be done with a capacity test through a load resistor and static voltage check for terminal potential. Get the manufactures battery curves and see if each cell follows the original curve. Also TEMPERATURE monitoring of each pack would be a very good idea. It's not practical for each small cell but at least each pack of cells. A number of identical thermistors wired in parallel through the pack would be one way to make the sensor and to bring teh two wires out to trip off cooling fans on or current limit into circuit.
Nice Project! I accidentally stumbled on this channel because I myself use 18650 cells as 4s and 6s field battery for my hobby ... now I watch all your vids in a row. Question: How often do you have to replace a cell and do you have to desolder the whole pack to exchange that cell? Thanks!
i have a test pod on charge using a small solar panel..i was told that anything above 12.6 would damage the cells yet the pwm controller shuts off at 13.8v and as yet no drama..the pack is charging and holding fine.. will keep you posted.. and i just use 10 amp blade fuses on the plus side..
+hacky2008 My brother mate lost his house that way. Burnt to the ground - was charging his wheelchair - don't know exact circumstances but i know he was using solar to charge his battery with a different charge controler.
I have a new opinion. I've been posting on several of the diy Tesla wall projects the following. The inside of a battery is a roll of sheet metal that's INSULATED electrically and thermally. So even when you think, "ahhh, the cell diameter is do much smaller than the length, surely the heat comes off it easier" nope, insulation prevents this. As it happens, this sheet metal roll, has many metallic tabs rolled in contact with the metal that connect the roll to the positive and negative terminals. That my friend is where the heat goes!. Look at any of jehu's thermal videos. You notice the ends of the cells get hotter first. Ok so I've establishes that... But heat is bad, and it travels from hot to cold. So what do we do? Add a little heater at the end of the cell such that the perfect pathway for that matter killing heat is blocked. One solution I just thought about today is your add some soldered tabs to the ends of the battery terminals. Then attach the fuse wire from the new finned terminals to the busbar. This way, you get heat transfer from the cell to convention and from the fuse to convection or the busbar.
Peter, I've been juggling cells into chargers and packs and I agree with your intent and question. The bottom line is that if the cell suddenly shorts internally it's possible it will overheat, explode, burn. However, from my hands on experience with five hundred cells, five ebike batteries, I think it's a reach to think that it might happen. I believe your questions about the fuses are valid but for a powerwall near your residence perhaps no one would argue it's a bad idea to install overcurrent protections.
+Gavin FreedomLover Fusing is a legal requirement & a common sense one in my opinion. Hope i never blow one, but if they do blow or fail i'll be thankful off the extra effort. Time is the equaliser :)
Yes mate I guess you are right , your project is coming along nicely and I am sure you will get a big leap in subscribers soon , keep up the good work brother!!
No Worries man, i know this stuff is hard work but the most annoying thing is the time sitting there editing videos ,keep up the good work mate !!!!!!!!!
i enjoy the editing, just don't have time - between working on my day job, recording for hours on end and making progress on the project then i have to take time out to edit.. it's 3:30 am here at the moment and i'm getting through 100+ messages and comments ... hhahaha who needs sleep anyway
Why do you need to fuse the positive and negative sides of each battery? Surely if it is causing a drain on the pack a fuse on the positive side would be enough.
I thought it was the max discharge rate of the cell (6A roughly for a 18650b) and to stop the short circuit. A faulty partial open circuit cell drawing only 1A is not a problem. I might be missing something in this video
I have only seen these batteries catch on fire when I physically overheated them with my soldering iron. do they spontaneously short? has anyone seen a fire result from this?
Nice, you built a pack with 4480 cells? Is that 16p14s20p, namely about 48V x 800Ah? Nice -- that is about 50 kWh! I have started building the same thing, with about 100 kWh. Application is a sailboat. My configuration is 16p2p14s20p. I am using new Panasonic NCR18650B from Alibaba - $3.28 each. May I ask what balancer are you using? And why did you choose 14s instead of 13s?
I see - this is for a powerwall. I have not visited the other links (just found out about them - thanks). So this could be a 24V system (7s) or a 96V (28s). It is important to stay at a multiple of 14, if you plan to use this on an EV. 13s will make it difficult to use in an EV.
It is 4480 at the moment and I have another 2240 ready to be installed when I can find the space.320p 14s configuration ( 80p14s x 4 ) its 40kwh with 35 easily usable without hurting the cells Sailboat project sounds challenging that for sure. I'm using a www.batrium.com BMS that is just amazing. 14s is better for my inverter and SOC
So that would be 4p14s80p (as it is read from right to left). So your system is 48V. May I ask what balancer-protector you are using, and how do you monitor the voltage of each of the 14 groups of cells in a 14s80p module? I also plan to install lots of solar panels (50 m2) to charge the pack. Volume is an issue, and each module of 2p14s20p must be portable because if something goes wrong the module has to be yanked out of a hole or something to be able to be repaired. The cells are 3.4Ah each.
@@ryanrobinson130 later packs have changed a little with nickel strip spotwelded to 3 cells then fused to busbar - but changing back to fusing every cell for safety
Pondering allowed (aloud): Something like AI (Artificial Intelligence) on a SBC (Single Board Computer) like an arduino or Raspberry PI could monitor the pack (for a quarter the cost of an BMS)?
You need to consider the formation of dendrites, this is the reason for the battery not holding the charge. It can be represented as a resistive load across the battery, this raises the temperature during charging. The way I would test, with reference to a new cell, determine the self discharge, if the self discharge is with in the normal delta that is a good cell. Maybe charge them, go back a week later and see what is going on as far as OC voltage, this will tell you what is good or bad Time consuming but best to be safe than sorry. But fusing is not bulshit, its good practice, however as you have demonstrated on another video, an internal short will result in thermal runaway, so containment and fusing are both good practices.
i guilt a pack of just 24 volt with 5 in parralel for testing and put cell level fusing on all cells then took it outside to test a worst case senario and hammered a nail completely through one cell,instantly the fuse blew and the cell fumed violently and disapated before it reached thermal runaway
your video implies the fuse would blow because it was taking to much draw, it would most likely blow if it overdischarged. the battery would blow the fuse if it got too hot and the resistance went through the roof, or if it overdischarged due to battery failure.
you could do it in three or four in series depending on the actual voltage you need. 18650 cells don't lend them selves too well to a 12 v environment. DO your research on what your application needs.
Jerry Blackledge wow only 9 and I though I had a little I have around 343 the i got from school I can go to the warehouse and gets hundreds of thaussnds new ones the were never used because they were from old laptops pallets full
why not only fuse each column? each cell will see the same amp draw. if a single cell shots to itself it would be internal anyways and there is nothing you can do to stop that from continuing. with that cell shorted the rest of the battery pack will try to overcharge the rest hopefully drawing enough amps to blow the fuse on the column. now you need 6x less fuses. allowing you to use automotive fuses that are more accurate and probably less losses in resistance increasing the efficiency.
I think it's just extra safety. If 1 cell dies in a bad way and turns into a short it will flatten the rest of the battery's maybe damaging them of starting a fire, also I'd something else in the system goes wrong and you pull too much current the fuses will save the day.......
You got 37 degrees (99 F) at .8 amps. Over time the battery will get worse and worse. How hot will the battery be at 5 amps?, 10 amps?. When it reaches 250C I think that is when it is over. So maybe a temperature monitor and switch that shuts off current to the pack if it reaches 40C anywhere on the pack might be better. Rambling myself.
Have you seen all my videos - Constant ramble ...lol Got the heat thing covered now with 84 temp sensors within one battery shed. And a Batrium Watchmon controlled Shunt Trip
Thank you. I was just watching the video. It is a good video. But, I will look at your Batrium setup as "DIY Tech & Repairs" uses that too. But what I want to do is a 4.0 system for car camping and use a cheap power bank to charge it (soldered to tabs inside unit). Then use boost converter to get 3 amps for the CF-18 Waeco Refrigerator. I don't watch all your videos anymore since I have a grid tie solar system and don't really need it. I watch for the entertainment.
As long as all safety measures of a good 18650 cell are intact (CID, PTC) even an internally shorted cell would trigger these 'fuses" before it went into thermal runaway. There may be some cheap chinese productions which lack all safety measures - so it is alway a good idea to have an extra safety that is reliable. I tried to pop several 18650 just by maltreating them electrically (massive overvoltage and/or overcurrent). The only thing that happened was popping the CID. The cell temp. climbed to around 100 C - no smoke, no fire - nothing. There may also be construction errors in CID /PTC so an extra fuse might be fine. The downside is: the wire fuse costs some energy and can also fail when not properly soldered or can even cause a short when just one end pops off an gets into contact with a neighbor cell e.g. How many wire fuses did you see trapping so far on your regular cells? And what was the problem with those cells? I hope you did check them...
Of course not. Just take one charged battery and connect + to - for a large current to appear and the fuse-wire should break otherwise the battery might burst or explode. That is what you want to avoid. You do not want a higher discharge current than what the battery can handle safely.
What your total amp hour for this big single module/80cells.. 3.7V 160Ah? probably about 2ah on average cells.. if you wanna avoiding your cell from overcharging current which may cause fire you should use more than 1C or 2amp fuse.. but it meant the discharge current also should not exceed more than 1C or 2amp.. the fuse also acted as safety protection circuit in case of + and - short-circuit.. When battery in parallel it will balancing the voltage by itself but doesn't means got same energy capacity.. death battery meant it can't discharge the energy anymore below 2.5V normally and can't suck the balancing current anymore because the internal resistance.. good and bad cell compare by capacity Ah.. the death cell probably can recover but the question is how much capacity it can hold.. charging this big single 160ah module at 6amp may take you more than a full day to fully charge it.. as far as i know.. Love you work buddy.. Cheers
Take a phone charger, bare the wires and use the red and black wires and tap the wires to the battery to boost the voltage then charge it on the imax B6 charger and see what you get. Why not? I did it with no problems and my batteries read 0.01~0.09v They don't stay @ 4.2v but 4.09~4.12v and 1415~1475mAh so waste not want not, you can still use the for a flashlight or e-cig
Yes the fusing is stupid if a cell goes bad it's not gonna suddenly put out so much energy that I can blow its own fuse the only reason the fuse is there is if you short the pack so you might as well just put one large fuse at the calculated say maximum draw that you want that pack to be able to run out so I've got 80 cells and they can all discharge one out and say an 80 amp fuse I'm just ball parking and be done with it
A copper wire is not a fuse. A fuse is made of a metal with a very low melting point, like tin or lead. Copper is a very good electric and thermal conductor, so heat build up in a copper wire is very slow. Besides, the melding point of copper is way too high for a fuse. Use the real thing: glass fuses; they are dirt cheap if you buy them in bulk. They come in different values from 0.5 A up to ... An important safety issue is the burning wire in 'open' air. A glass envelop fuse prevents the wire setting fire on the adjacent objects when it blows.
I tried the glassfuses and also Pico fuses back in the day - ugly & builky and quite hard to see a visual fault. I worked it out in the end. I think this video must be 2 years old now.
Im building a 24 cell battery pack for a smaller project. testing fuse wire that broke at 7A would waste 5W of power per fuse under normal operation (4A) with the limited supply of onyl 24 cells thats unacceptable and too wastefull
Assume that all of the batteries are in parallel. Then, think of possible failure modes for a cell without a fuse.If one cell was an open circuit, it would be just like removing one cell from the pack. You would likely lose some capacity, nothing catastrophic.If one cell loses some of it's capacity to store a charge, the pack would lose a little capacity, again nothing catastrophic.If one cell suddenly shorted out, all the current from the other cells would go through that one cell. How many amps would that be? Could that cause a fire?Think of the Galaxy Note 7 problem.
Leslie Franklin Im making my first 18650 pack. My thinking aligns with yours: the batteries in parallel would not do much but hurt capacity if they go bad, but the batts in series should have fuses...is that right?
Each of the batteries should have a fuse to protect against fire. You organize them in parallel groups to get capacity. Then you organize those parallel groups in a serial arrangement to get voltage. For example, if each 18650 has a capacity of 2,000mAh(milliamp hours), then a parallel group of 10 of them would give you a capacity of 20,000mAh. If you have any batteries in parallel, then each one needs a fuse. Then you need to determine what voltage you need. Each battery can operate from 2.5v(volts) to 4.2v. However, you want to limit that range for a more predictable overall voltage and to extend the life of your 18650 batteries. As you put parallel groups of batteries in series, you add the voltages for each of those groups to get the voltage range of your battery pack. For example, if you are charging each parallel group to 4v and allow discharging to 3.5v, and you have 3 parallel groups connected in series, then the total voltage can range between 4x3=12v when fully charged to 3.5x3=10.5v when drained. It really depends on your application on how you need to arrange these. If you feel unsure about how to do this and the potential risks involved, I would suggest studying more or consulting a professional. Battery fires are potentially dangerous.
So get yourself a data logger and decent volt and ammeter and see if the charge and discharge curve is out of whack compared to a healthy cell. If not, it's fine.
Once a li-ion hits zero, it's capacity goes away. It may still charge to 4.2V, but will not hold a charge. It also poses the danger of dendrite growth which can cause an internal short. The question that I have is how long must the cell be at zero before its capacity is lost. I am told that it is immediate - but have not tested that. Charging a li-ion anywhere below 3.2V should be done at very slow rates, like 0.1A, in order not to damage the cell.
that's not sound reasoning, if you're connecting cells in parallel, you need to fuse them, period, and you need to use a proper fuse too, not something that can arc and sustain the current flow; why? because if one of the sells goes, you do not know how it will go, you cannot generalize and say that you have this dead cell and everything is fine, therefore generalize that you don't need fuses, you do not know how the cell will fail, it can be a dead short, what's going to protect the pack then?
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I already played with a few batteries and I see that better ones have integrated fuse protecting it from overchanrging, undercharging and most of all, overheating. If it heats too much, there is pressure fuse which will break before battery catch on fire or explode. In case of shorted battery it will blow quite quickly, I had this happen two times when I used some shitty charger from china (which was designed to charge only those high capacity 99999Ah cells from china for 1$). Anyways, if it's shorted, then it's secured. The problem is that if you draw high amperage and you have a lot of dead cells, then working ones will drain quickly and finally they start to blow one after another. You'll end up with a lot of killed batteries which could be saved by simple fuse. In my case it's the only reason I think about fusing them. My main fuse will secure batteries from shorting outside of battery back and internal shorts are handled by built-in fuses to each battery. The only problem is that my 150A cut-off fuse will not prevent batteries from draining too fast if big part of them is already dead.
Well...... I'm running a 48V 250Ah 16S50P LiFepo4 pack for an RV and used 0.125mm tinned copper for fusing, and tested it out. The fuse blows at 3.25A, red hot at 3A, discolored at 2.75A. I did this "in theory" because I didn't ever want the batteries to put out or take more than what the system is rated for. I could've used 0.1mm and still had been fine because 0.1mm blew at 2.75A. The cell fuses are rated around 40A higher (all together) than the main fuses (which are 125A mains). So it's not necessarily about protecting each individual cell, but more of an added protection according to the systems rating, although if a cell was to short, I'd hope it would blow. The main focus was to make sure the batteries are never giving or taking more than what the system's hardware can handle.
oh, well what I meant was that at best ( my figuring) is that if the cell will charge from the other batteries in the bank it will eventually reach the packs voltage but the cell will always leak current due to an internal resistance in the cell. Now that I say that out loud I'm not sure how a fuse would prevent that...
G'Day mate. enjoying your project. If you haven't yet check out batteryuniversity.com/ there's plenty of info that can help you on lithium cells , including answering your questions which you ask in this video, all related to 3 internal systems. 1.Built-in PTC (positive temperature coefficient) protects against current surges. 2.CID (circuit interrupt device) opens the circuit at a cell pressure of 1,000kPa (145psi). Safety vent releases gases on excessive pressure buildup at 3,000kPa (450psi). The last one here was what happened when you squeezed the cell which would have ruptured the separator and is a newly added safety feature since 2008 making the 18650 a super safe cell and makes it really hard to set them on fire nowadays. 3.Separator inhibits ion-flow by melting process when exceeding a certain temperature threshold.
Yep found that out when three cells went dead short in my powerwall. Didn't even know till I pulled a pack and retested it. Fuses blew and saved my wall from possible damage. Very happy i didn't give up on the fusing idea... thought many times it was a waste of effort fusing every cell. No i know it's a requirement !!!
how did it save you? it has to be pretty exceptional circumstances in order to get the right conditions to blow the fuse, seems a bit belt and braces to me.
Haha... good video, maybe the best question you ever raised!! Great, lots of people sharing their opinion here, in the end there is not "right" or "wrong"... it all "depends" on countless factors... anyway great comments here =]
batteryuniversity.com/learn/article/low_voltage_cut_off BU-808a: How to Awaken a Sleeping Li-ion batteryuniversity.com/learn/article/safety_circuits_for_modern_batteries BU-304: Why are Protection Circuits Needed? Some stuff on this.
Yep, i'm over 6k cells fused - im very happy for that choice many years ago. I can honestly say i've blown 100's of fuses doing dumb things or accidents.
+Google+ SUCKS BALLS - the worst forced social network Back to basics - are you even kidding I"M STILL AT THE BASICS learning.. come on i'm here to try, fail, learn & repeat - such is life. Thanks for your comment :) Pete
I believe the fuse is for when the battery is shorted, and only for that reason.
if the battery gets physically gets damaged externally, or if the battery internally is damaged from overcharging maybe, it may short out. the current from the complete battery pack would try to travel through the shorted battery. If a fuse is installed it will blow and then will disconnect the shorted battery from the pack.
The battery you are testing on the bench is not shorted. it may be discharged and hold nearly no charge anymore. but it is definitely not short. if it was, it would have burned the fuse wire immediately.
It's exactly what I think . If he will use shortened cell it will burn fuse instantly . I recovered few cells from 0v .
Agree, the fuse is there to prevent a explosion once the battery is shorted. This may occur when the internal insulation get punctured (use of time, overload, physical damage). Personally I'm using those for my current project:
www.ebay.com/itm/100pcs-Glass-Tube-Fuse-Axial-Leads-3-6-x-10mm-6-3A-6-3Amps-F6-3A-Fast-Quick-Blow/290945050705?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
One could make the same argument over fusing in a motor vehicle or even a house. There is a distinct possibility that you may never trigger a fuse over the lifetime of a system. But, do you really want to gamble with your family's safety? Even the improbable is possible.
Another good analogy it's all a learning process and I'm happy to learn .
if a cell completely shorted it could prevent a fire
it very well could :)
It could. But short circuited cells are extremely rare. It's more common that the internal protection of the cell kicks in and disconnects the cell from its casing, rendering it useless but preventing a dead short and eventually, the infamous lithium fire!
I had a battery that shorted in my custom built ebike battery without fuses and it drained the entire parallel cell of about 15 batteries right down to zero and the entire row was absolutely piping red hot. None of the batteries could be revived. Had to rip out the entire row and rebuild it with 15 replacements. Definitely looking into getting fuses now.
It is quite a bit harder on eBikes because of the way they are treated ie. bouncing around i think our style fuses will break just through micro movements over time. let me know how you go and what path you end up taking
If you are using significant power, those fuses are going to be horrible for an ebike. I am using cells rated for 20 amps continuous, and I also absolutely do not want unnecessary voltage sag under load. So that means with a 21s12p pack, I want to be able to pull upwards of 100-180A continuous if desired without overheating the pack, blowing fuse links, or having a ton of internal resistance buildup in the battery. I have ordered a full BMS so there is a degree of protection (only output isolation, not internal). I also built a resistance welder, so that I don't roast the batteries trying to solder to them. I will be cautious with the pack for a while until it proves to be stable, but internal fuses just isn't an option. I'm fairly sure a dead short would probably roast the weld points in the cell that is shorted.
What's the alternative though? When I had a bad cell it took out the entire row with it finding them all at 0 volts. Wasn't happy at all.
TheFootbaldd And obviously tesla cars have a fuse on every cell which pull way more power and bounce around more than any ebike. Completely open to suggestions here. Just want to produce the best battery I can that will last the mileage. Thanks
There is a significant difference between a highly engineered pack like the flat packs Tesla uses and an e-bike. The mechanical agitation in one of their packs should be significantly less than in a cycle for obvious reasons. There are many fail-safes designed into modern non clone 18650s to prevent runaway conditions. Could you show some documentation on your isssue with pictures of the build and the failure?
hey punch a screwdriver through a cell or crush it in a vice and see if it get an internal short. Then see how many amps it draws i think that part of the reason why the fuses are there... ?
I've tried that with Dell laptop 18650's, it was uneventful to say the least. Got warm but no smoke or venting, just had some liquid come out.
That is alone. But what if you put 1000A across the terminal (the amount of current one of these packs will put out).
It depends on the quality of the batteries. Batteries with high internal resistance will not be able to produce high currents. So, the often detested Chinese quality can actually be safer :-) Their capacity though is too low for serious use.
Looks like your long fuse wire is just acting like a resistor. Remember, ohms = MALT (material, amperage, length, & temp).
To replicate it, use a short section of fuse wire.
sounds like a plan :)
I had a brain-fart.....A is for area, not amperage. Good work on your videos!
Fair question
Fuses serve one function, to conduct current through a circuit and then melt immediately if more current flow than their rated maximum limit goes through them. They are used to prevent dangerous overloading in a circuit and that's basically it. There are some"tricky" uses for fuses but the reason to fuse every single battery in an array like that is to automatically isolate one single cell from the rest of the array should an internal short failure occur in one of them. In cell arrays with high numbers of cells in parallel, a dangerous amount of current will be able to flow from the other cells in to the shorted one which may lead to a thermal cascade that results in failure of that bank of cells and possibly a dangerous fire/explosion. Having a "dead" battery in parallel with many fully charged batteries will cause an unregulated amount of current to flow in to the low voltage cell as the charge naturally balances out. It usually isn't going to result in a catastrophic failure but it unbalances your battery pack and stresses the bad cells even more.
Thanks for your imput - pete
When running these batteries in vehicles, depending on the number of cells you have in parallel, the idea is to prevent current surges through a single battery. Some controllers can pull up to 650 amps. Well running 3.7 volts from 1 battery at 1 amp, the single battery is going to have to give off the whole amp alone. If 2 batteries are in parallel, then it will only require 0.5 amps from each to make up the 1 amp. Going back to the 650 amps, 650 cells would need to afford 1 amp a piece. Cut the number of cells in 2 to 350, each cell climbs to 2 amps. If a battery is bad chances are it will try to discharge at a higher rate than the others (a short) causing the fuse to blow before the battery heats to a point at which the contents literally start to boil.
well said, my friends. In conclusion, yes fuse wire is needed on Tesla Car, and Power wall. Not required in Laptop battery.
Ahh, i see, it's primarily to protect the cells from discharging above the designer intend. Hence it's a very simple over-discharge contraption.
But how it is correlate to the battery that in dying condition? i've looked around but i can't seems to find a way or system that can read individual cell's health when use in power pack such as power wall.
If cells are in parallel, it is difficult to determine the health of an individual cell, as the other cells will cover up for it. So you will have to look at the group of parallel cells, and compare it to other groups with the same number of cells. If the group charges too fast, or too slow, compared to others, then most likely one of the cells in the group has an issue. This has to be resolved because even if the BMS catches this anomaly, it will cause a good part of your energy storage to be wasted, until you replace the cell. If the BMS does not catch it, then that can turn into a safety issue.
hy, i build a 48v pack. and i fuse every cell with a resettable fuse with are rated at 3a. so if my motor try to take more then 3a from my pack it wil disconect, and reconect when the amps get down again.
sorry for my bad english
I agree with BillTheBox - the fuses protect against a rare single cell shorting internally - in which case there will be a rise in current. And if the short is bad enough the current will rise enough to blow the fuse.
My working assumption is that this type of fault is more likely in an electric car situation where the battery is being stressed. Jahu mentions in one of his vids that he found blown fuses in his recycled battery packs after using them in the Samba. I suspect that's why he switched to using real Tesla packs.
For a Powerwall we are looking at much lower max current demands so the chances of a battery short are likely to be less. But, again - that's just my hunch.
I think the main benefit of the fuse system is it's an easy way to solder the batteries with just a soldering iron. I think it's the best DIY process for connecting cells up.
+Paul Kennett I've only just managed to disprove my own thoughts - but missed the moment when i panicked and launched the battery into the old pool area (we are digging out our pool) i'll try to edit together what i have and voice over the rest - Found one cell that was at 56deg 13min after removing it from the charger
+HBPowerwall I've had only one over heating cell, that I've noticed, since I've started doing this - probably 1000-ish cells. I assumed it was because my iMax clone was over-charging (which it was) - so bought my iCharger for charging. Maybe it would have overheated on the iCharger too. Freaky though.
Sounds like you had a close call.
As somebody already pointed out these fuses help only when cell is shorted out or whole pack load is so high that amperage load for particular cell is higher than fuse can keep. Now, it will not and it should not blow fuse if some cell just worse than others, has internal open circuit, or has internal resistance higher than others. More, just imagine that your pack voltage is 4V and you connect some cell charged up to 2V. Let say that you have 5A fuse. To blow that fuse your cell have to have resistance less than (4-2)/5 = 0.4 Ohm. If your cell is not new that its internal resistance can be higher than that. To make things more complicated, when you connect that cell to the pack it' voltage will increase pretty fast especially if cell is not so good. So current will be even less and not enough to blow the fuse. So, just leave the fuses alone, they will do the work WHEN ACTUALLY NEEDED. Try to apply Ohm law and you will be amazed how it easy to explain a lot of things. Thank s for your great videos. I like your curiosity and wish you the best.
fuses are for when you get a puncture ( eg you drop the pack )
or when you short both poles ( you should have a master fuse for that )
But the point isn't that it will help every time, you just want to be saved that one time when there is a short in one battery that happens to have developped a low resistance short, and even if that is only a 1/1000 chance I would still do the fuses. ( low resistance means a lot of current can pass through the battery )
But that's me, I blow myself up and burn myself pretty often so safety precautions are key for me
Also I don't think you understand completly how the batteries die and what shorting is/why people don't use batteries that where under 1 or 0.5 volts.
-> in a lithium battery you are taking advantage of "reversible" reactions,they can go both ways ( discharge and charge )
-> when you go under 3v then the reaction goes on to a further stage that IS NOT reversible ( at least not without dumping a massive voltage to the poles ) this 'deposit' of conductive material on one of the poles will sometimes manage to make contact ( via the walls of the battery or other ) with both poles, effectively "shorting" the battery
-> because that short is, as I said, a small deposit, it is generally a high resistance short ( battery self discharges and doesn't take a charge without warming up )
I can clarify if needed, I don't know if I explained that correctly
+BillTheBox I get it, just want to see it, does that make sense? I'm still doing it and i'm happy to eat my words when they save my ass/house/shed/car/boat/bikes etc :)
+BillTheBox Yup.. the gap between + and - terminal in this 18650 single cell is only about 3mm..without the protection cap and heat shrink plastic you easy can short this terminal in case of carelessness or traumatized to produce over current and create heat resistance causing cell leakage, burst or even fire and start the chain reaction to the other cells in this big module..
Like any fuse there is a fuse curve of current vs time. So the fuse will never blow at it's rated current, 10x rated current it will open in minutes, 100x rated current in seconds, 1000x rated current 0.1 sec, etc. Or something like that. The fuse curve is usually on a log scale. So the fuse will protect against a real fault or a low resistance high current fault in one battery.
Been a while since I did this video but learned a bunch since and have had several fuses save me some issues I think !!
Making the best 18650 battery packs is, with wire bonding at the positive pole of each 18650 cell, for example in the Tesla lithium car battery pack.
Best is subjective - and would be considered when money was no object - in the desert of Africa where they don't even own a soldering iron the BEST has a different meaning. Best part about these projects are their scalability
I used 2 matched cells recovered from a laptop for a 2S battery in a holder, and had one cell spontaneously go bad, short, idk, but begin smoking as I walked past it in my living room.
I’ve made a bunch of batteries over the past few years and that’s the only time it’s happened.
Now I mostly use 18650s in an esp8266 battery charger, and will be building lifepo4 packs for 12v.
Fusing every cell in a parallel battery pack is critical to my personal safety, and when I build large packs I will fuse them in some way. I am more concerned that people are using, in effect, random wire, not wire intended to blow at a specific amperage, and to blow in a "clean" way without a lot of metal flying around.
For me, I'd rather experiment with fuses, measure the voltage drop across them, and the heat they produce from that drop. From there, perhaps finding the kind of wire they use would work.
Also remember a lot of things will affect wire fusing: the solder itself acts as a big heat sink, so there is a minimum distance from the solder joint where the fusing will occur. The fuse wire will drop more voltage than a larger wire, so there is loss due to heat across each wire (even if it's not warm, there is a drop, and it will vary by amps). Also, a "slow death" of a cell where it is drawing near to but not over the fusing level will just make a localized heater, which may itself cause a fire. There's a reason fuses are in little glass tubes.
from my pack going down all I found a bad cell did was drag the voltage of the hole pack down as it was acting as a constant load
What is the load that you are connected to? I think the problem with what you're trying to do is the resistance internal of the dead battery versus the resistance of the pack. The dead battery has a higher resistance meaning when connected to a load the total resistance will be higher and depending on the load the pack will heat up more quickly or not deliver the rated power at the efficiency that it was designed for. I guess I was wondering what test conditions you have setup, still don't know the load that is connected to?
Well you know my view from the start on fusing each cell, the fuse is to protect the wire/cable .the only way imho that the fuses will ever blow is if the main +&- busbar are shorted out and if it was me I would fuse each busbar
Is the fuse wire only needed because you are paralleling all 150 batteries on the same bus? What if you soldered 14 in a series, and then only doubled in parallel? Then the Volts would be high (say 48v), but the amps would be low (say 8-10A). Would you need it on that? Would it even be possible to short the batteries in series, or would you have to short every battery in that series?
If keeping the parallel to only 2 would prevent you from needing to fuse each cell, would you then need to fuse each pack if you then paralleled 100 of those on the same bus (one fuse per pack/28 batteries)? What is the advantages of high amp and low volts, vs high volts, low amps?
i've thought about this myself. I'm thinking for stationary energy storage/low peak draw; I would maybe have fuse wire that pops very close to the expected max draw. Like so close you have false positives
also test with a same length that is in the pack.
So how do you deal with a single 18560 that has an internal short and shorts itself out and heats up to the point of flame and pop? An internal short is not pushing or pulling current so can't blow a fuse. No current across the fuse equals no blown fuse. But you could still get a fire.
+Pete McWade You start filling out paper work i guess
If only one cell blows the damage will not be tremendous.
If the rest of your cells are shorted because of this one cell the damage might get much bigger.
Not even a protected cell is prevented from the situation you are describing. You could build a thick wall iron case around each cell :-)
Some commenters have the wrong idea ... we're discussing fusing ALL cells , which seems ridiculous to me ....in the video, the longer the dead cell was connected to the pack the less current it took ... the problem to avoid is a dead cell slowly draining the pack at half an amp or so ...a fuse won't stop that !
The solution must be to have large blocks of cells in parallel , put these in series to get the voltage required , then when in use check the voltage of each component pack once a month ... if one pack is low look at the base of the cells with a thermometer , to see which cell is draining the pack.
Individual cell fuses have been now proven to be required (by me) 4-5 cells dead short blew the fuses nothing happened. UNTIL I pulled the pack and noticed blown fuses - retested and wow, no thank you .. Fuse both ends not just the positive side
You maybe correct ... I don't have enough understanding about how these cells go bad ... But for sure there's no need to have a fuse on both ends ... and make sure you use real fuse wire (alloy of lead and tin) copper wire or galvanised is not suitable , many reasons( I can elaborate if you like) ...www.answers.com/Q/What_is_the_Composition_of_fuse_wire
oz93666 any recommendations on type of fuse wire to use on these type of cells?
I've been looking a lot into fuses over the past week, and have revised my opinion a little ... I believe tinned copper is OK as long as red hot blobs of molten copper are not a problem on the rare occasion one blows , lead tin fuses will melt at 300C , so only warm molten metal flying about ...I've just ordered some 31AWG tinned copper wire for use as fuse on these cells .
There's still a lot to learn about the way these cells fail I don't believe they can completely short , just fail in a way their internal resistance and self discharge goes too high and they drain the pack ....and this will eventually blow a fuse.
If anyone does have a cell which blew a fuse when in a pack examine it carefully for voltage int resistance , will it still hold some charge? This will teach us a lot.
fuse all the cells connected in parallel, don't fuse any connected in series, that would be pointless, just add a fuse at the output, if it makes sense, it might not for your application
cells have a ptc and cid and will limit there own current and pressure. However, when in series above 30v, a PTC can char and CID can arc in high current situations. This may be the reason tesla use fuses. The PTC research was conducted by nasa & CID by clermonte university
I had a LiFePo4 battery get shorted once (due to me dropping the pack on concrete). I had no fuses or fuse wires, and the cell made a direct short. The cell got blazing hot and drained the 3 cells in the pack in a matter of a minute or two. I'm sure that was over 10A shorted, and if i had just used fuse wires or slo-blow minis, this would not have damaged the other cells!
Of course, had this been a Lipo or LiCoMXXX or whatever other chemistry it certainly would have lit up, possibly destroying the pack as well as my equipment!
It just seems like overcurrent protection for individual cells instead of for entire pack. Not sure how much it would help since cells are unable to drift in voltage when connected so significant current flow should not happen. Tho fusing like you do with wire seems to be a weak point and get damaged when instaling/moving the pack
The way I see it is that if one cell has a fault on it it may start off as a small fault with the cell but as time goes on the fault will only get worse and not better until it gets bad enough to short totally, The cell is encased in metal so any problems at the positive end may short out to the case negative and the next thing you know is all those battery's in parallel are feeding into this new path of least resistance. Most faults occur over time especially major ones, those faulty cells you tested probably had a BMS attached to them so they shut down pretty quickly before any real problems occurred like fire or explosions. I soppose it all depends on what type of fault is wrong with the cell, chemical or the way it was manufactured
I don't bother most of the time with fuses on the pack and never use fuse wire on the individual cells unless it's a really large, high voltage one. Generally I will use a nickel strip that can handle the current I'm aiming to draw through it and that will fail when the current goes too far above that. But again, for high amperage packs, I will use an inline fuse just after the pack and before the BMS as the fuses I use act faster than the BMS' own OCP. Generally in the realm of about 30 amps is good for the ones I build if they need to be fused.
For cells that fail in a pack, I have only really encountered cells that refuse to accept a charge or that act like a massive resistor, sapping away current and getting warm but haven't had one fail dead-short and catch fire. Probably because I am extremely careful with charging and discharging my lithium cells. I only use dedicated Lithium chargers and will always referring to the datasheet for my specific cells to ensure that I am not cramming excessive current into them during charging.
Every video is mandatory for battery science safety
I think I learn more from messing around than books. thanks for your comments
So what you have done with putting the cells in parallel is nothing more than what is done with the large Prismatic style cells that use flat leaves all stacked in parallel within the cell. So each of those 18650 cells is like a single leaf within the large flat packs. So I'd say its just along for the ride. Will you even get one of those to short out within the paralleled pack? Not so sure you would. I'd like to see it actually happen. Might just be a very rare event. One in which there is little to worry about. Jehu has driven his in his Bus for some time now and they are all fine and he built his out of mismatched to a point. You may have one weak one in the bunch but it may not be a problem as they are all pretty much sharing the load. Unlike those in series. If you have a bunch in series you could cause a cell to go. This is why I just use prismatic and bottom balance. If I have a cell so far out of whack from the others I just replace that cell. I can't go in and replace a leaf within the prismatic cell. Those leaves within a prismatic are not fused. Why would you then fuse the 18650 cells you put in parallel?
its to protect from a rare chain reaction : i read about Li Ion chemistry, that especially while dischared or more precise while lower than minimal rated charge level (empty) , the cells "can" build up metal crystals within the chemistry of the cell over time. not just reducing capacity, but it can lead to internal short circuit (or at least low R somehow). Now if such a cell would go bad like that in a battery with many parallel connected cells, there could be a giant short circuit current, even if all the parallel cells are supposed to be "low" or "empty" (on li ion they are never really "empty" , you know) . And so that could cause a chain reaction of events. cells and cabeling then overheat and go haywire, not unlikely to catch fire. THAT is what these cell fuses are supposed to protect you from. If one cell goes short circuit, its fuse will blow, since all the parallel cells together will pump more current into it than its single fuse can handle. its not guaranteeing that the whole thing wont catch fire, but a single cell may be easier to handle or safely isolate from the others, hopefully not resulting in some chain reaction.
these cell fuses are NOT really about balancing. just protecting each cell from massive overcurrent , either while charging but more likely while discharging or just being connected in a battery with others.
Fusing high current batteries is a safety option - should one short it will prevent a fire. If one shorts and you have a number of banks in series, you will have a fire quicker that you can blink as the other series batteries will over-charge in the bank and teh parallel ones will short maybe creating an explosion.
Determining faulty cells will need to be done with a capacity test through a load resistor and static voltage check for terminal potential. Get the manufactures battery curves and see if each cell follows the original curve.
Also TEMPERATURE monitoring of each pack would be a very good idea. It's not practical for each small cell but at least each pack of cells. A number of identical thermistors wired in parallel through the pack would be one way to make the sensor and to bring teh two wires out to trip off cooling fans on or current limit into circuit.
Have arduino solution for that, temp probe for every pack with three stage fans low, med, and holy frigbiskets.
Nice Project! I accidentally stumbled on this channel because I myself use 18650 cells as 4s and 6s field battery for my hobby ... now I watch all your vids in a row. Question: How often do you have to replace a cell and do you have to desolder the whole pack to exchange that cell? Thanks!
i have a test pod on charge using a small solar panel..i was told that anything above 12.6 would damage the cells yet the pwm controller shuts off at 13.8v and as yet no drama..the pack is charging and holding fine..
will keep you posted..
and i just use 10 amp blade fuses on the plus side..
+hacky2008 My brother mate lost his house that way. Burnt to the ground - was charging his wheelchair - don't know exact circumstances but i know he was using solar to charge his battery with a different charge controler.
its fine...its confind to the outside test area..not in the house..:)
I have a new opinion. I've been posting on several of the diy Tesla wall projects the following. The inside of a battery is a roll of sheet metal that's INSULATED electrically and thermally. So even when you think, "ahhh, the cell diameter is do much smaller than the length, surely the heat comes off it easier" nope, insulation prevents this. As it happens, this sheet metal roll, has many metallic tabs rolled in contact with the metal that connect the roll to the positive and negative terminals. That my friend is where the heat goes!. Look at any of jehu's thermal videos. You notice the ends of the cells get hotter first. Ok so I've establishes that... But heat is bad, and it travels from hot to cold. So what do we do? Add a little heater at the end of the cell such that the perfect pathway for that matter killing heat is blocked. One solution I just thought about today is your add some soldered tabs to the ends of the battery terminals. Then attach the fuse wire from the new finned terminals to the busbar. This way, you get heat transfer from the cell to convention and from the fuse to convection or the busbar.
Like your videos! Your wire falls off at 0:53 and you just 'stick' it back on - is that really a good enough connection for the test?
too late now :)
Peter, I've been juggling cells into chargers and packs and I agree with your intent and question. The bottom line is that if the cell suddenly shorts internally it's possible it will overheat, explode, burn. However, from my hands on experience with five hundred cells, five ebike batteries, I think it's a reach to think that it might happen. I believe your questions about the fuses are valid but for a powerwall near your residence perhaps no one would argue it's a bad idea to install overcurrent protections.
That test was a long time ago.. and fuses have saved me a few times since i think. Still a good way of me thinking through a process.
I prefer the voltage monitoring system for cells in series but for parallel cells prob best to stick to fuses.
i have been getting cells that are 0v but after charge and cap test they end up being 1800+ma
+donzi joe Yes, but for how long ?
I've never fused any of my stuff, still going strong, how are you finding mixing cells as I try not to do this, thanks.
+Gavin FreedomLover Fusing is a legal requirement & a common sense one in my opinion. Hope i never blow one, but if they do blow or fail i'll be thankful off the extra effort. Time is the equaliser :)
Yes mate I guess you are right , your project is coming along nicely and I am sure you will get a big leap in subscribers soon , keep up the good work brother!!
Cheers thank you
No Worries man, i know this stuff is hard work but the most annoying thing is the time sitting there editing videos ,keep up the good work mate !!!!!!!!!
i enjoy the editing, just don't have time - between working on my day job, recording for hours on end and making progress on the project then i have to take time out to edit.. it's 3:30 am here at the moment and i'm getting through 100+ messages and comments ... hhahaha who needs sleep anyway
Why do you need to fuse the positive and negative sides of each battery? Surely if it is causing a drain on the pack a fuse on the positive side would be enough.
Thinking aloud - fusing both sides is dumb and useless in hindsight
I thought it was the max discharge rate of the cell (6A roughly for a 18650b) and to stop the short circuit. A faulty partial open circuit cell drawing only 1A is not a problem. I might be missing something in this video
or a lot, it was a thinking aloud process
I have only seen these batteries catch on fire when I physically overheated them with my soldering iron. do they spontaneously short? has anyone seen a fire result from this?
Personally i've only seen them have issues when someone does something wrong - over charged, over heated ect.
A-Bit O'blarney
- Of course they start on fire. They will burn a hole through the case of your laptop ...
the battery + terminal of the battery is connected to the - of the battery pack, so it's discharging the battery
the length of the fuse REALLY matters. Shorten it up and watch how fast it burns up.
This is very true..
Nice, you built a pack with 4480 cells? Is that 16p14s20p, namely about 48V x 800Ah? Nice -- that is about 50 kWh! I have started building the same thing, with about 100 kWh. Application is a sailboat. My configuration is 16p2p14s20p. I am using new Panasonic NCR18650B from Alibaba - $3.28 each. May I ask what balancer are you using? And why did you choose 14s instead of 13s?
I see - this is for a powerwall. I have not visited the other links (just found out about them - thanks). So this could be a 24V system (7s) or a 96V (28s). It is important to stay at a multiple of 14, if you plan to use this on an EV. 13s will make it difficult to use in an EV.
It is 4480 at the moment and I have another 2240 ready to be installed when I can find the space.320p 14s configuration ( 80p14s x 4 ) its 40kwh with 35 easily usable without hurting the cells Sailboat project sounds challenging that for sure.
I'm using a www.batrium.com BMS that is just amazing. 14s is better for my inverter and SOC
So that would be 4p14s80p (as it is read from right to left). So your system is 48V. May I ask what balancer-protector you are using, and how do you monitor the voltage of each of the 14 groups of cells in a 14s80p module? I also plan to install lots of solar panels (50 m2) to charge the pack. Volume is an issue, and each module of 2p14s20p must be portable because if something goes wrong the module has to be yanked out of a hole or something to be able to be repaired. The cells are 3.4Ah each.
Seems like the fusing would add a substantial resistive loss under peak load
How about 1 fuse for every series row?
Current peak load is 0.4 amps - zero issues there.
@@ryanrobinson130 later packs have changed a little with nickel strip spotwelded to 3 cells then fused to busbar - but changing back to fusing every cell for safety
well from what ive found the possitive cap peice can break the seperator and short or thermal runaway can occour thats it
Is fusing cell bullshit? I ask you, is a tesla battery bullshit? No ! thats the answer for your question. saftey first :-)
At that point it was bullshit, couldn't find any reason why it was useful... HOWEVER since changed my tone as it saved me several times in a row.
Pondering allowed (aloud): Something like AI (Artificial Intelligence) on a SBC (Single Board Computer) like an arduino or Raspberry PI could monitor the pack (for a quarter the cost of an BMS)?
Many have gone this route, not my choice - I'll pay 100x more to feal 1000x safer any day
You need to consider the formation of dendrites, this is the reason for the battery not holding the charge.
It can be represented as a resistive load across the battery, this raises the temperature during charging.
The way I would test, with reference to a new cell, determine the self discharge, if the self discharge is with in the normal delta that is a good cell.
Maybe charge them, go back a week later and see what is going on as far as OC voltage, this will tell you what is good or bad
Time consuming but best to be safe than sorry.
But fusing is not bulshit, its good practice, however as you have demonstrated on another video, an internal short will result in thermal runaway, so containment and fusing are both good practices.
I don’t understand how one cell in a battery with lots of other cells in parallel could become a short circuit.
Time to study how Dendrites form ...
you can chane to time and currant limmit on the imax in the setting too
i guilt a pack of just 24 volt with 5 in parralel for testing and put cell level fusing on all cells then took it outside to test a worst case senario and hammered a nail completely through one cell,instantly the fuse blew and the cell fumed violently and disapated before it reached thermal runaway
sorry about the typos need glasses
I think the fuse will be useful for certain types of faults within the battery.
yep,
your video implies the fuse would blow because it was taking to much draw, it would most likely blow if it overdischarged. the battery would blow the fuse if it got too hot and the resistance went through the roof, or if it overdischarged due to battery failure.
ok, thank-you for your comment
I will not pretend to be an expert :) but i do enjoy this project.
Good Video. Thanks for sharing your power wall experience! Liked & subbed.
Thanks for joining the community!
How to wire those batterys togetter I got 9 of them waitingv to make a 12volt battery
you could do it in three or four in series depending on the actual voltage you need. 18650 cells don't lend them selves too well to a 12 v environment. DO your research on what your application needs.
Jerry Blackledge wow only 9 and I though I had a little I have around 343 the i got from school I can go to the warehouse and gets hundreds of thaussnds new ones the were never used because they were from old laptops pallets full
There's an option called safety timer, you can disable it.
why not only fuse each column? each cell will see the same amp draw. if a single cell shots to itself it would be internal anyways and there is nothing you can do to stop that from continuing. with that cell shorted the rest of the battery pack will try to overcharge the rest hopefully drawing enough amps to blow the fuse on the column.
now you need 6x less fuses. allowing you to use automotive fuses that are more accurate and probably less losses in resistance increasing the efficiency.
yes parralel cells will self balanceup up ,the more cells that are in parralel is when it becomes dangerious as it can spike to hundreds nof amps
I think it's just extra safety. If 1 cell dies in a bad way and turns into a short it will flatten the rest of the battery's maybe damaging them of starting a fire, also I'd something else in the system goes wrong and you pull too much current the fuses will save the day.......
those dead laptop battery, always has a bad cell, but it never caught on fire.
You got 37 degrees (99 F) at .8 amps. Over time the battery will get worse and worse. How hot will the battery be at 5 amps?, 10 amps?. When it reaches 250C I think that is when it is over. So maybe a temperature monitor and switch that shuts off current to the pack if it reaches 40C anywhere on the pack might be better. Rambling myself.
Have you seen all my videos - Constant ramble ...lol Got the heat thing covered now with 84 temp sensors within one battery shed. And a Batrium Watchmon controlled Shunt Trip
Thank you. I was just watching the video. It is a good video. But, I will look at your Batrium setup as "DIY Tech & Repairs" uses that too. But what I want to do is a 4.0 system for car camping and use a cheap power bank to charge it (soldered to tabs inside unit). Then use boost converter to get 3 amps for the CF-18 Waeco Refrigerator. I don't watch all your videos anymore since I have a grid tie solar system and don't really need it. I watch for the entertainment.
As long as all safety measures of a good 18650 cell are intact (CID, PTC) even an internally shorted cell would trigger these 'fuses" before it went into thermal runaway. There may be some cheap chinese productions which lack all safety measures - so it is alway a good idea to have an extra safety that is reliable.
I tried to pop several 18650 just by maltreating them electrically (massive overvoltage and/or overcurrent). The only thing that happened was popping the CID. The cell temp. climbed to around 100 C - no smoke, no fire - nothing. There may also be construction errors in CID /PTC so an extra fuse might be fine.
The downside is: the wire fuse costs some energy and can also fail when not properly soldered or can even cause a short when just one end pops off an gets into contact with a neighbor cell e.g.
How many wire fuses did you see trapping so far on your regular cells? And what was the problem with those cells?
I hope you did check them...
ichardnanis
- Even with "fuses", the cells continue to start on FIRE ...
length of fuse and whir causing resistance try with the length it has while in the battery holder this would be a true test of curent and fuese
this question keeps me up at night. lol
If Tesla does it I will do it too. As easy as it is. There is nothing "extra" when we speak about safety.
If your fuse wire has too high of a resistance to melt itself at 3.7v, then you are using the wrong fuse wire.
Of course not.
Just take one charged battery and connect + to - for a large current to appear and the fuse-wire should break otherwise the battery might burst or explode. That is what you want to avoid. You do not want a higher discharge current than what the battery can handle safely.
What your total amp hour for this big single module/80cells.. 3.7V 160Ah? probably about 2ah on average cells.. if you wanna avoiding your cell from overcharging current which may cause fire you should use more than 1C or 2amp fuse.. but it meant the discharge current also should not exceed more than 1C or 2amp.. the fuse also acted as safety protection circuit in case of + and - short-circuit..
When battery in parallel it will balancing the voltage by itself but doesn't means got same energy capacity.. death battery meant it can't discharge the energy anymore below 2.5V normally and can't suck the balancing current anymore because the internal resistance.. good and bad cell compare by capacity Ah.. the death cell probably can recover but the question is how much capacity it can hold.. charging this big single 160ah module at 6amp may take you more than a full day to fully charge it.. as far as i know.. Love you work buddy.. Cheers
if i am hired for designing tesla .. i will use the battery fuse .. to increase safety level in case of battery short circuit (due to any causes) ..
haven't they always used cell level fusing?
@@HBPowerwall i mean if tesla cars haven't exist yet ... lol
Take a phone charger, bare the wires and use the red and black wires and tap the wires to the battery to boost the voltage then charge it on the imax B6 charger and see what you get. Why not? I did it with no problems and my batteries read 0.01~0.09v They don't stay @ 4.2v but 4.09~4.12v and 1415~1475mAh so waste not want not, you can still use the for a flashlight or e-cig
Say, you didn't go to The Edge recently, did you?
+hwwonB21 The Edge?
Batteries have internal protection, fuse wire would be the 2nd line of defense.. breakers would be the 3rd line. =D
Not all but yes...
Yes the fusing is stupid if a cell goes bad it's not gonna suddenly put out so much energy that I can blow its own fuse the only reason the fuse is there is if you short the pack so you might as well just put one large fuse at the calculated say maximum draw that you want that pack to be able to run out so I've got 80 cells and they can all discharge one out and say an 80 amp fuse I'm just ball parking and be done with it
A copper wire is not a fuse. A fuse is made of a metal with a very low melting point, like tin or lead. Copper is a very good electric and thermal conductor, so heat build up in a copper wire is very slow. Besides, the melding point of copper is way too high for a fuse. Use the real thing: glass fuses; they are dirt cheap if you buy them in bulk. They come in different values from 0.5 A up to ... An important safety issue is the burning wire in 'open' air. A glass envelop fuse prevents the wire setting fire on the adjacent objects when it blows.
I tried the glassfuses and also Pico fuses back in the day - ugly & builky and quite hard to see a visual fault. I worked it out in the end. I think this video must be 2 years old now.
Im building a 24 cell battery pack for a smaller project. testing fuse wire that broke at 7A would waste 5W of power per fuse under normal operation (4A) with the limited supply of onyl 24 cells thats unacceptable and too wastefull
Yup, no good from efficiency, and power standpoints. You didn't even mention pack voltage sag under load due to the fuses.
what if the cell fails short?
+Thiago Ennes ?
Maybe if a cell is bad and abused and becomes a short circuit. Not possible?
on ebay you have a cheap wire fuses for fev dollars 100 pcs, way better than wire
Assume that all of the batteries are in parallel. Then, think of possible failure modes for a cell without a fuse.If one cell was an open circuit, it would be just like removing one cell from the pack. You would likely lose some capacity, nothing catastrophic.If one cell loses some of it's capacity to store a charge, the pack would lose a little capacity, again nothing catastrophic.If one cell suddenly shorted out, all the current from the other cells would go through that one cell. How many amps would that be? Could that cause a fire?Think of the Galaxy Note 7 problem.
Leslie Franklin Im making my first 18650 pack. My thinking aligns with yours: the batteries in parallel would not do much but hurt capacity if they go bad, but the batts in series should have fuses...is that right?
or is it the opposite and I need fuses for the batts in parallel but not in series?
Each of the batteries should have a fuse to protect against fire. You organize them in parallel groups to get capacity. Then you organize those parallel groups in a serial arrangement to get voltage. For example, if each 18650 has a capacity of 2,000mAh(milliamp hours), then a parallel group of 10 of them would give you a capacity of 20,000mAh. If you have any batteries in parallel, then each one needs a fuse. Then you need to determine what voltage you need. Each battery can operate from 2.5v(volts) to 4.2v. However, you want to limit that range for a more predictable overall voltage and to extend the life of your 18650 batteries. As you put parallel groups of batteries in series, you add the voltages for each of those groups to get the voltage range of your battery pack. For example, if you are charging each parallel group to 4v and allow discharging to 3.5v, and you have 3 parallel groups connected in series, then the total voltage can range between 4x3=12v when fully charged to 3.5x3=10.5v when drained. It really depends on your application on how you need to arrange these. If you feel unsure about how to do this and the potential risks involved, I would suggest studying more or consulting a professional. Battery fires are potentially dangerous.
So get yourself a data logger and decent volt and ammeter and see if the charge and discharge curve is out of whack compared to a healthy cell. If not, it's fine.
Acquired many cool new toys since this video was made :)
Once a li-ion hits zero, it's capacity goes away. It may still charge to 4.2V, but will not hold a charge. It also poses the danger of dendrite growth which can cause an internal short. The question that I have is how long must the cell be at zero before its capacity is lost. I am told that it is immediate - but have not tested that. Charging a li-ion anywhere below 3.2V should be done at very slow rates, like 0.1A, in order not to damage the cell.
Indeed. That's why you should check the discharge curve once it is charged.
that's not sound reasoning, if you're connecting cells in parallel, you need to fuse them, period, and you need to use a proper fuse too, not something that can arc and sustain the current flow; why? because if one of the sells goes, you do not know how it will go, you cannot generalize and say that you have this dead cell and everything is fine, therefore generalize that you don't need fuses, you do not know how the cell will fail, it can be a dead short, what's going to protect the pack then?
I already played with a few batteries and I see that better ones have integrated fuse protecting it from overchanrging, undercharging and most of all, overheating. If it heats too much, there is pressure fuse which will break before battery catch on fire or explode. In case of shorted battery it will blow quite quickly, I had this happen two times when I used some shitty charger from china (which was designed to charge only those high capacity 99999Ah cells from china for 1$). Anyways, if it's shorted, then it's secured. The problem is that if you draw high amperage and you have a lot of dead cells, then working ones will drain quickly and finally they start to blow one after another. You'll end up with a lot of killed batteries which could be saved by simple fuse. In my case it's the only reason I think about fusing them. My main fuse will secure batteries from shorting outside of battery back and internal shorts are handled by built-in fuses to each battery. The only problem is that my 150A cut-off fuse will not prevent batteries from draining too fast if big part of them is already dead.
Well......
I'm running a 48V 250Ah 16S50P LiFepo4 pack for an RV and used 0.125mm tinned copper for fusing, and tested it out. The fuse blows at 3.25A, red hot at 3A, discolored at 2.75A. I did this "in theory" because I didn't ever want the batteries to put out or take more than what the system is rated for. I could've used 0.1mm and still had been fine because 0.1mm blew at 2.75A. The cell fuses are rated around 40A higher (all together) than the main fuses (which are 125A mains). So it's not necessarily about protecting each individual cell, but more of an added protection according to the systems rating, although if a cell was to short, I'd hope it would blow. The main focus was to make sure the batteries are never giving or taking more than what the system's hardware can handle.
After two years of doing this cell fuses have now saved me a few times - several cells have gone zero volts & blown the fuse..
Craig Dohner
- Tinned Copper wire is *NOT* a fuse ...
no the fuse only blows if the battery goes into short and the other oarralel cells start dumping high currfent into it
by battery i ment the gell
it wont dect reverse polarity ,or over current of the total battery ,its only part of a saftey system
At best the non fused cell will have a parasitic effect on your bank
+GrimL0gic I'm going to google that word now...
what word?
+GrimL0gic parasitic
oh, well what I meant was that at best ( my figuring) is that if the cell will charge from the other batteries in the bank it will eventually reach the packs voltage but the cell will always leak current due to an internal resistance in the cell. Now that I say that out loud I'm not sure how a fuse would prevent that...
P = I2 R
All those fuses add up to a lot of resistance ...
Chane, the fuses are in parallel, so the total resistance decreases everytime you add a fuse.
@@cecilcooper6210 No, the WATTS lost to heat is the SUM of all cells ...
G'Day mate. enjoying your project. If you haven't yet check out batteryuniversity.com/
there's plenty of info that can help you on lithium cells , including answering your questions which you ask in this video, all related to 3 internal systems.
1.Built-in PTC (positive temperature coefficient) protects against current surges.
2.CID (circuit interrupt device) opens the circuit at a cell pressure of 1,000kPa (145psi).
Safety vent releases gases on excessive pressure buildup at 3,000kPa (450psi).
The last one here was what happened when you squeezed the cell which would have ruptured the separator and is a newly added safety feature since 2008 making the 18650 a super safe cell and makes it really hard to set them on fire nowadays.
3.Separator inhibits ion-flow by melting process when exceeding a certain temperature threshold.
+Da Rainmann Thanks for info :)
tried your experiment. did blow the fuse..
I have shorted a battery using fuse wire setup and it works. Hope that helps. It worth doing.
Without a doubt a necessary safety device
EXAMPLE: cell level fuse against 48v and ohm: 48v= 12S = 12S x3.0V = 36v = 48v -36v = 12v@12A easy possible across 1 cell. DESTROYING WEAKEST LINK.
Yep found that out when three cells went dead short in my powerwall. Didn't even know till I pulled a pack and retested it. Fuses blew and saved my wall from possible damage. Very happy i didn't give up on the fusing idea... thought many times it was a waste of effort fusing every cell. No i know it's a requirement !!!
i have been thinking the same thing for a while now. i have decide not to fuse the battery i am making at the moment.
+Kris Harbour your mad. Please fuse has saved me twice.
how did it save you? it has to be pretty exceptional circumstances in order to get the right conditions to blow the fuse, seems a bit belt and braces to me.
plus lots of cells have fuses in them already. how many lithium batteries have you opened? and how many had fuses?
Processed 8-10000 cells none had cell level fuses.
Haha... good video, maybe the best question you ever raised!! Great, lots of people sharing their opinion here, in the end there is not "right" or "wrong"... it all "depends" on countless factors... anyway great comments here =]
+ElectricBike (Bruno) Thanks for the phone call Bruno, we must combine forces to create mayhem!
batteryuniversity.com/learn/article/low_voltage_cut_off BU-808a: How to Awaken a Sleeping Li-ion
batteryuniversity.com/learn/article/safety_circuits_for_modern_batteries BU-304: Why are Protection Circuits Needed?
Some stuff on this.
+Darin Bicknell tar
I disabled the imax timer. that was so annoying.
Yes, but I feel it is there for a reason, been running my imax for months and it's still holding up.
Go on I double dare you lol...short the busbar to see if the individual fuses blow
+1bigsyd I CAN confirm that the result of this test is YES - I had to try, pity I forgot to turn on camera - man it smelt bad
put a 20p pack of samsung 30q together then try connect a flat one things going get rewal nasty
You need a weaker fuse.
or more power! lol
Tesla does it, so it has to be the right thing to do.
Yep, i'm over 6k cells fused - im very happy for that choice many years ago. I can honestly say i've blown 100's of fuses doing dumb things or accidents.
steveeb
- So tell us exactly, what does Tesla do ...
Cool!
with a flir camera you can see the dead cells.....
If your around :)
i dont have one..... and live in switzerland dude
I don't have one either lol Flir works only when your holding it, fuses work all the time ..
#1 Maybe you need to get back to basics.. like what are fuses used for. #2 why Tesla does it is way out of your hobby-scope
+Google+ SUCKS BALLS - the worst forced social network Back to basics - are you even kidding I"M STILL AT THE BASICS learning.. come on i'm here to try, fail, learn & repeat - such is life. Thanks for your comment :) Pete