BMS Battery Module - Can you Series connect them?
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- เผยแพร่เมื่อ 4 ต.ค. 2024
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I have heard from so many sources (including the manufacturers) that a series setup is not possible but I have personally used 2 * 48V, 30Ah packs (each with their own separate BMS) in parallel and series for years on a daily basis without problems. As you correctly pointed out - the load must be disconnected to reset the BMS in case of any fault detected. Thanks for confirming it jehu
But what if it fails? Everyone says, well what if it doesn’t I say
@@jehugarcia Right on brother. Enjoy your channel very much - thanks again
@@jehugarcia As long as the result is not fire and brimstone I agree :) if the only problem is you either trip or blow your bms- great. Worth the money/ hassle
I used two 4S BMS in series. When they failed it took out $150 battery. But I don't think a dead short like that is very common when a BMS fails. Using the BMS to power a contactor/relay would have prevented this mishap.
so many BMSs don't support this function and only have problems with B- and P-
I like that you said you like to test and not just talk. That's what I do and it gives me the experience I need.
This is the best TH-cam channel in the world
How much did he pay you?
Questions normal people probablly could never answer, but thank to this man, we, got the answers. :)
I LOVE the Headway cells... Great stuff... I use them to keep my Lipo's charged when I'm out flying my RC sailplanes..... Pick your missions and these batteries will make it happen. Thanks Jehu! ........... Have Fun, Weav
I think its great that you are doing things with these Headway batteries and talking about them. Please do let us know what you think about them compared to other types of lithium batteries. I'm very curious about those and the differences between those and the others. Thanks for the video Jehu, always enjoy them.
I've done some testing on these BMS'es, under normal conditions you can put them in series, but the Vds of the fets is a limiting factor, not for 2 x 4S in series, but in the 16S the FET's Vds max is 80V's, I've tried it, when you make a 64S out of 4 16S and trigger an over or undervoltage on one cell, the FET's simply short out and you won't even notice (they make a short circuit) leaving you without cell over and underprotection. That combined with the poor 35mA balancing current is a dissaster waiting to happen ;-) Also like most BMS'es, when a cell goes defective in open circuit mode, the balancer explodes ;-)
Hi i want connect 4x48v 25ah battery pack in series to make it 192v dc for online ups will it work and is it safe
With wat he said no it explode
Mine makes the same problem you described one of the boards keeps shorting it's circuit and forwarding the others voltage
So if you stay in the 4s range you would be ok you think? I've got 4 12v 4s batteries trying to hook up in 48v via bms. Getting so much conflicting info on this feed. Thinking bottom line that I can just have a second discharge negative that does not go via bms for powering motor. And then go via bms in parallel for charging. obviously no low voltage cutoff and a few other things like temperature etc... but at least they stay balanced. can always just keep an eye on voltage meter
@@stormashish shares video link
Another informative video. I'm really into watching anything regarding the headway 38120s right now. I was thinking how many of those larger bms's you have but you said you ordered those for that project. Since I'm still interested in getting the most amperage out the headways in 12v. Also from last video you did on the headways you put a link for buying used cells. I wish I wouldve seen that before I ordered mine from China. I couldve got 16 cells from the site you linked instead of 8 all though mine will be new. I can already see me running 24 of the headways and possibly running a bms per 4 cells just to get closer to my 1000amp goal. Now I know this will be expensive as all get out but everyones gotta have a hobby lol
Thanks Jehu, I was wrong in your comments and I thought I read it somewhere that you couldn't/shouldn't
Great video again
I guess the real question is charging.
If you try charge them as a single 24V battery one BMS will cut out when charged before the other has finished.
Normally a BMS would do cell balancing but since it doesn't know about the other BMS it would end that when its cells are full/balanced but the other BMS may not be finished.
However that might be ok, since with a series string you only get the capacity of the lowest cell anyway.
Yes so it does what’s is supposed to do, disconnect as soon as any cell group reaches 3.65v
Would that be mittigated by having a second loom that does a parallel hookup that you just switch over? I guess thats a hassle for most use. But in my situation of having a boat motor running off 48v but wanting to charge from one or two 12v panels. Ie a versatile parallel series switcheroo loom
@@jehugarcia will the second pack keep charging if the other is fully charged?
You did not mention charging with 24v? Is that possible.
Great video!! You should do another using a 3s with a 1s and 2s!!!
Now wait a minute. When the left side BMS opened the circuit, there shouldn't have been a current path through the series circuit at all. It should have acted like you unplugged one of the XT60 connectors entirely. My guess is that when the left BMS faulted and disconnected the load, there is still some small amount of current feeding through the balance wires from those batteries to complete the circuit. You should recreate this test and use a sensitive multimeter to probe around and see how the current is actually flowing. You might have just discovered a serious flaw in the design of those BMS circuits.
Good theory.
Check the reply from darren smith
That's exactly what I came to say. There has to be a leak through the balance wire. If you put them in series and only one trips out, but the voltage is still enough to be usable by the load, my bet would be on smoke.
chineseium bms they haven't got a clue i think people think they protecting cells ...i think they full of shit its not like it can isolate a single cell which ive seen 3 mosfets setup just for 2 cells in series with separate chargers so would need a few for big packs lol
I will explain this to all of you. The BMS is switched off but the other one is still on. There is no leak. The mosfet switches have a body diode in their package. The current from the other pack is trying to reverse charge the pack that is off, but trough the body diode of the mosfets the current is simply passing in reverse. That however is a problem because the body diodes have normal diode characteristics and a 0.5-0.7 volt drop trough them. That means that they will be dissipating about 50-100W if the load is trying to pull 120-130 amps. The body diodes also have a different, much lower current capability than the mosfet itself can handle. Basically if you do this and your load doesn't care about the input voltage like the inveter ( a starter motor, light bulbs or some sort of switching power supply with wide voltage range input ) you will kill the mosfets on the BMS. Probably explosively because than they will short out the cells in the pack.
You kind of need an active element to manage the BMSs so if one gets cut off it will cut off the rest too. Sort of a 48 volt BMS-MS. That way if one BMS cuts out then it will cut out the others too until all are back online. Also it could help balance the voltages on each BMS.
I know that some BMS for single cells have to either be removed from the load or need a charge to enable the power again.
So you can check if charging the pack after the protection triggered reenables the BMS.
No matter how many in series, each BMS will have a 12v potential across it on the mains.
Tony B. Yes. But!!! It should be like a cheap set of Christmas tree lights. Once one goes out, they all go out. If the tripped BMS had no bleed-through, the meter should have read zero
the more you put in series if one trips the more voltage will go across it if one turns off, if the voltage is too high the mosfets will blow because of the too high voltage.
@@SuperBrainAK Only if the FET's don't break the connection completely. When Jehu disconnected the balance wires I expected to see a 0V potential because one of the BMS' broke the series chain (like Sailing ADVENTUROUS mentioned with the Christmas lights). But apparently there is some kind of bleed-through going on where when the FET's break the connection, a direct bypass is used, which makes the disabled BMS act like a wire. Though, this would only become dangerous when you are charging the system, during normal operation, the system would just see a voltage drop equivalent to the amount of failed BMS links.
Jonathan Overes The mere fact that this happens means you cannot safely use them in series. This is considered an unsafe failure of protection equipment. The potential for fires as a result of this failure is very real. It is entirely possible the failure of one BMS turned this into a ticking time-bomb.
Great vid jehu, but I thought we covered this already.
Bms can be used in series n inverters can be used in parallel for bigger loads.. tested n true..
I’ve never addressed it specifically
072723/1028h PST 🇺🇸 Thank you for the demo on 2X12V LiFePo4 BMS controlled Batteries in series; to load (discharge) Most DIY enthusiasts do not demo this. One prominent battery manufacturer (BB) also did not speak or demo this, as explicitly as you did. Best wishes.
This is just a thought and maybe I'm totally wrong
1) if you have more packs ,and you connect the output of the BMS in parallel ,you are fine , at the beginning ( in terms of time)the highest pack will discharge, and then they will keep going together
2) if you have more packs , and you connect the output of BMS in series , you are fine ,but you have a limitation on the number of BMS that you can connect in series , because the output stage of a BMS is basically a pass transistor , and every MOSFET has a DRAIN-SOURCE breakdown voltage , so when a BMS shuts down is output, if there is a V d-s greater than the V d-s breakdown you will destroy the MOSFETS.
3) this is a sketchy one , because apparently everyone that is building a powerwall with the jehu's kit is doing this without noticing.
In every powerwall there is at least one BMS board with three BMS's connected in parallel ON THE BATTERY SIDE ,in that powerwall every cell is connected in parallel with all the other cell ( basically you have 7 cells in series and n cell in parallel where n is the number of modules) , fine nothing wrong with that, here comes the tricky part, every BMS has a balance connector , and you connect all the all the BMS and all the cells in parallel , when you charge up the battery all the balance MOSFETS must work together to keep the packs balanced, but every MOSFET is different from the other , and every MOSFET has a different threshold voltage than the other, the one with the lowest voltage will kick on immediately trying to balance the pack, since it's on it will heat up , and is threshold voltage will become lower and lower , so basically what I'm saying is that from all the BMS's on all BMS boards of a powerwall ONLY ONE MOSFET is in charge of keep balanced all the cell ( of the same group so there will only one MOSFET for all the third cell of the series)
Apparently no one had notice that because all cells are roughly equals so the balance mosfets are having an easy life, but during the years those cells will drift , and the balance MOSFET must work pretty hardly to keep everything balanced , at that point one balance MOSFET will blow up and then the MOSFET with a slightly higher threshold voltage will blow up , and a MOSFET ..... and so on until every MOSFET will blow up
I'm studying electronics engineering at the moment , and i'm far from an expert , this is my thought, so if there is someone more expert than me please tell me that I'm totally wrong and that I'm an idiot , and also why I'm an idiot
I really could use your help I'm trying to learn more about this , I been having trouble trying to get the right batteries for ebikes losing money because of my ignorance.. 👍👍
Thanks, dude, it's clear.
it'll work, that's massive, these may perform in more of a controlled voltage output(that runaway effect) with the squirrel cage , looks like being conservative with the voltage effects the capacity when the amperage could be more useful
I just purchased enough batteries to make 4 of those 12 volt 200AH units... Going to put them all in series, for 48 volts...
Calm down dude, save some poo-nanny for the rest of us
@@andyluvsvengeance, 🤪🤣😆😂😜
I will like to know how to
Dale Patterson did it work?
Thanks a lot for the video!! im trying to replace lead acid gel batteries on my old APC 1250 , uses 2x12v 7 or more amperes batteries in series to get 24v, i have 18650 to build a pack and two bms 4s 40a, i will try to do the same and test it. my worst concern is the safety .. i am affraid of 18650 when i am not in home... inside of a ups, even is ventilated with a constant fan
Each bms is only receiving 12 volts even in series. So it's safe to connect in series.
Only caveat is that since total volts go 24v, load should not pull more current than treated by each bms because that will switch off BMS
I've personally tried with 4 cheap 4s lifepo BMS plugged in serie for a scooter. It was a disaster, there always was a pack which gave up very quickly and i had to unplugged and switch 2 pack randomly to reboot the system and keep pulling load. I gave up the idea and rebuilt a single 48v pack with the four 12v packs.
With mosfets I'd advise checking the max voltage and max current each can handle between drain and source. Gate is much lower and I'll say perhaps protect the gate side when wanting to bump up the voltage or current. But bare in mind the voltage is devided between them if am understanding correctly.
I have never worked with BMS but should be on the same principle.
It might be worth checking the components themselves?
48V (and 60V) setups don't get the attention they deserve, more so if you need a solution for serious AC power.
But series BMS introduces a major failure concern, that being the more of them you add the chances of one failing increase. That's a problem because replacing a dead BMS means taking the entire pack offline, unlike an active 1S balancer where you can disconnect the individual banks, bridge connections and still keep your battery working. Also since series BMS shares the load, having just one fail can strain the rest of the system, even if this doesn't show up as an error or is only afterwards apparent. With a 1S balancer it doesn't matter if the failure is with the cells or the balancer, the failure won't affect the rest of the system.
I would not recommend a BMS for a 16S pack or larger - stick with active balancers.
What makes 24V setups neat is their portability - carrying a 12V battery in each hand is easy, wiring them up in series can be done quick. and if you have a quality PSW inverter you can get some real use out of it.
I am still pissed off at your ghetto charging solution from the last video - please make a better one.
Just wait till 400v, 600v, and 800v are more common..
Didnt find anyone saying that:
The built in MOSFETs have a maximum Voltage Rating.
If one of the BMS shuts off. The switched off MOSFETs get the Voltage from the whole Setup so in that case 24V.
If the Setup Voltage is higher than the Voltage rating of the MOSFETs, the MOSFETs are damaged at the second the BMS switches off !!
You can not series connect BMS !!!
Most Mosfets can handle 75V Some even less. The higher the Voltage rating the bigger is the ON Resistance. (not necessarely but mostly).
If you get to Voltages over 100V you get problems getting MOSFETs that are capable off switching high currents. Thats why you use Relays for Voltages in cars.
Also of course higher voltage ratings are more expensive.
For high Voltage fast switching, IGBT are used. They are much bigger but can handle Voltages around 1000V. But they are expensive.
Ewald can a BMS be parallel linked without all of the concerns I'm reading on here?
Fine and good for 12-24v. But what if you kept seriesing those until you ended up with something like 150-200v? I'd be nervous about the voltage rating of BMS's internal fets. Even large 32s-capable ones (134.4v li-ion) usually only have 150v fets in them (lower voltage rating = lower ir of the fet = less wasted power/heat). 3 of those in series = 400v. So what happens when 1 shuts off for some reason and the other 2 keeps going? Almost 2x rating = I'd think the bms would end up in flames, and if the cells are capable of high current (ie pouches or big prismatics with
I think I would not actually put the BMS in series. To avoid this problem I would use a contactor-relay so the BMS would not actually be exposed to the Circuit voltage. The output of each BMS would enable a mosfet or solid state relay as part of a series. Each BMS would power one relay. If all relays or activating then the signal would ultimately reach the contactor. If one BMS fails then the contactor shuts down. This is commonly referred to as a and gate array.
Jehu, It might help to add a wiring diagram, it will be much more clear on how to have them connected. I am having a problem making the connection myself. Thank you for all your videos, they have been an inspiration. Thank you
Well, I tried to download a schematic drawing of 3 each 48v battery packs with BMS to have something to discuss, but it looks like TH-cam or this group does not allow it. Thanx anyway
I see a secondary problem here. Once one BMS detects that a battery is fully charged it will go open circuit. This will stop the other battery from charging fully and your two 4S cell groups will quickly go out of balance. Or worse still it will go into bypass mode and the second battery would get the full charging voltage intended for a 24V setup rather than a 12V setup. The only way around this would be to charge using two 12V chargers (which defeats the purpose of a 24V system). I don't think I'd be recommending this system. Much easier and simpler to use a BMS designed for 8S. The only other way around this is to have smart BMS's like Battleborn does.
I'm usually with you Jehu but this is a really bad idea. What we should be telling people to do is use an 8S BMS for 24 volt LiFePO4. This will also give ~24 volts out of the system, without having two BMS boards in series.
My bad ideas are my best ideas, what are you all afraid of? Show me where the problem is and I’ll drink the coolaid.
@@jehugarcia I'm not trying to crap on your party. I always support your builds, so easy bro. In regards to protections, the BMS boards are not in synced. One board shuts down, the other gets a massive inrush of current, if there's a big load on the inverter at the time. Why wouldn't you just use a single 8s BMS?
Because people are building/ using 12v boxes with integrated bms. This is the question at hand, not if you can build a 24v system with bms
@@jehugarcia fair enough, I got that part. You asked for feedback in the video so I was just pointing out the potential.
Thank You. Please consider one more on that 12 volt reading after shutoff. Your 24 volt inverter shutoff but what if there was a load on there that would take 12 volts?
Because no one has responded to Ewald although it was not that long a go , I would agree with him, 24V you may be OK but above that I would not as he stated the BMS that switches off the load will see the whole system voltage across it's terminals, obviously with single 12V pack that will only be 12V but as you stack 12V packs it will quickly rise.
Great guide. Thanks! You could use a tripod, though. It will make your videos more professional.
In not after professionalism
Always enjoy your video. Does it make sense to use 5 of this pack and put them in series for a 72V/80V battery pack ? or go with 20S build ?
Good stuff man nice follow up
I have a Question, Dear! I have a set of 18650 -171 total batteries and I have put them in 3S- 3 packs each pack is 19*3
the question is, should I use one BMS for the three packs or should I use 3 BMS that?
Note: I have 3 BMS 40a will I get a power of 120a If I merge them?
Thanks :)
Can we use parallel.
I am planning to use multi 13 s packs for inverters.
What will effect if any 1 trigger during load or charge....?
Great info.
I would like to see u actually test an battery bank in a car. 12v
Great test. After the first BMS trips, can you please test the current capability of the remaining 12V system i.e. hook up a 12V load through the meter. That would show the bleed-through capability of the BMS that had tripped. I would have thought it shouldn’t allow any significant draw?
Near zero "bleed-through" unless the bms has failed shorted.
Never thought about it but you could series the BMS. They don't see any more then the cells wired to them. You could even charge them in that configuration.
The far left balance wire attached to the positive terminal of the left battery pack is completing the circuit after the left BMS module trips out. Because of this the answer to can you run them in series is no, you cannot. In series operation if either BMS module trips out you risk burning up wires and lighting the tripped out BMS on fire.
Thanks for this video. Currently researching how bms work internally. I am told the bms have to have isolated grounds to be placed in series. I don't know how that is done. The bms measures the voltage of the pack so it uses an microprocessor and an A/D. I don't think the bms can just use a diff. measurement when the common can be at such a high voltage. Still have not figured this out.
You can go up in series. The one thing that you didn't mention is the lost of Efficiency. 1 BMS will have less voltage drop because each BMS will add a significant amount of resistance which will create more voltage drop, 2 or more BMS in series will be more inefficient and trigger LVC earlier than 1 BMS.
The most dangerous part of this setup is that the short circuit protection in the BMS cannot handle more than 12v. So although everything else will work in series if you short circuit by accident it will kill the BMS.
Should getting a 24V BMS be the solution? I have a another question. I want to connect four 36V 15ah in series-parallel to get 72V 30ah what are some tips and advice? It's for my ebike.
@@billychampy316I did that with 48v in parallel and then also in series for 4 batteries @ 96v. In my situation I bypassed the bms for output and kept it for charging .
Now I’m putting 2 44v batteries in series… this time I’m planning to use the bms’s but made sure to get 2 bms’s that can handle 88v.
I`m currently building a range extender battery for my Peugeot 508 RXH HYbrid4.
Stock battery is 168S1P 5,5Ah Ni-MH. Nominal voltage 201,6volts (same as the Prius, different shape battery tho).
My plan is to use 126 8Ah Headway LiFePo4 batteries in a 63S2P configuration using 3 150A 21S BMS boards in series.
Hope it works.
Almost guaranteed to blow up the BMS's due to the high voltage on the mosfets
I am doing a 12V-2 battery(280Ah) LiFePo4 system with 2 BMS to a 1800 watt inverter. Would both BMS need to be 150+ BMS or can I divide the load. I'm new to this
Will both 12 volt banks discharge at the same time or will the first 12 volt bank be discharged first.
Have a doubt...can I charge it..when it's in series...btw your vds are the best.....been following it up from a long time and it's really really helpful and educative....👍
Each BMS only sees 12v across them , not the 24v total voltage.
How could you possibly give this man a thumbs down for trying to help you to who gave the thumbs-down you are a real piece of crap thanks for trying to help us all out of here
Tom Jones I didn’t give him a thumbs down but I can completely understand how someone who is observant could. The fact that after the left BMS shut down the circuit still had 12v means that one of the balance wires on the BMS is completing the circuit. This is an exceptionally dangerous condition that could easily start a fire if the battery pack was under load.
I’m connecteing two of my 20v power drill batteries in series onto my 40v electric bike. Do I need a BMS?
Thanks you!
What about charging
Will it still charge properly if we connect 2 bms in serries?
Of course it will work if during Discharging.
But the question is, will it still work during Charging process???
I am using 5 bms boards in series {3x3s + 2x4s} one of them fail and keeps getting out of circuit until I disconnect and reconnect the load, I think it's the forwarded voltage that mosfets could not take it
Good morning can you tell me what is the name of the volt meter you’re using please thanks
jehu you could easily configure this for 120v 240v ect, off a high output alternator the amount of amps they can handle 'this could get dangerous' with a speed control turning the alternator unregulated , the caps could consume more than the alternator could put out, might push a electric bulldozer, the caps should have alot left over after turning something with high rpms like a leaf blower motor or a vacuum cleaner motor turning the shaft on an alternator.
How are you getting 12v after the BMS triggers? It opens the circuit right? Should be at 0v? Or am i missing something
My thoughts too. Very strange
Same here
I think it’s ghost voltage, fet leakage won’t actually support any current
@@jehugarcia maybe the BMS was passing some current from the B+ (small wire) to the load minus (not B-)
My assumption is that only one of the two BMS got triggered and that's how he was getting 12v. If both would have gotten triggered then it clearly would be 0v, but 12v was enough to trigger the inverter shutdown.
What about recharging? Can you charge them in this configuration?
how about charging? 24v or 12v?
Jehu ! I can see a potencial problem with series connection of BMSs. As we could see when you disconnected one bms it sees 12v over the mos switch. If there where three bms in series and one disconnected, the bms will see 24v over the mos switch. So the bms must then be 24v or more.
Thanks !! I applied You're setup to a 16s 100ah 48v battery with two JBD 24v 100A bms.
I'm getting ready to put I to work.
Do you have any advise for something to look for before to use it in a home system ?
Please update whether this worked or not. Im considering doing the same thing
Can you parallel connect different batteries with different bms? Should i use an additional bms that treats both as individual cells?
Can i later on charge them through the same charger as one battery?
Other than both having the same voltage as we connect them and protecting them with schottky diodes from overflow current from the other battery, what safety measures would be needed?
what is the energy density on these lifepo4s?
Many thx to those who will enlighten me!
And thank you for those enlightening videos!
Wooow nice one brother
Informative as always! Can you post a link to that meter/monitor? I thought it would be easy to find on amazon but maybe my criteria are unrealistic (e.g. up to 160VDC)
I orderd min to build a 24v system with 132 cells.. thanks for the vid
Hello
If i made 4 12 volts batteries in series with 4 bms’s Can i charge them with a 48v charger ❤
Will the packs become unbalanced from each other?
Yes, will be just like normal series.
Only if packs are not well matched
You would be better off getting 2 8s BMSs and building 2 24v Batteries and running them in Parallel. The series BMSs wont correctly. Balance the whole system.
@@jehugarcia and Philip Housel: to clarify, well matched in this case means that all the cells are the same capacity, the same ESR value, the same ESI value, are exposed to EXACTLY the same temperatures during their life, and have the exact same number of charge/discharge cycles on them. There may be other parameters that must be taken into account that I don't know about too. The point is, it is going to be pretty much impossible to keep them perfectly in balance over the long term. They will drift. The reason other chemistries like Lead Acid can be put in series without a BMS is because you can overcharge those cells without them self-destructing, meaning you can apply enough overvoltage to sufficiently charge the lowest cells without hurting the highest cells, thus keeping them top-balanced at all time. With Li-Ion, the charge cycle is interrupted as soon as the first cell reaches "full", regardless of the state of the rest of them. So, whichever pack is lowest in charge state will gradually drift to be lower and lower every time you recharge it. Of course, depending on how vigorously you cycle them, the higher pack will deteriorate at a faster rate due to higher charge state, and that will reduce its capacity. In this way, they may actually balance out over time, slowly deteriorating the higher pack until it matches the lower one. Not sure if that is what you meant by "unbalanced" or not though.
@@WarrenGarabrandt It depends. In the RV and marine community, they have found that the large LiFePO4 prismatic cells stay in balance when used in low c use. These cells do need balancing when used in high draw usages like electric cars but not when used in low c situations.
All the 12v lithium batteries that you can can purchase have a BMS in them. They allow a least 4 in series for a 48v system. The BMSs in all of the batteries are basically the same circuitry. Connecting batteries in series is just a basic voltage divider. You only ever see the individual voltage across each.
As long as each battery is the same capacity it should be fine. Each one needs to be at the same state of charge when connected. Then the same amount of current flows through each battery.
As long as you do not run the bank too low , neither should cut out. Also I would only run the current at about half the rating of the BMS, then you will never go into overcurrent cutoff. I never use a BMS at more than 70 -80% of its rated current. If so only for a brief period.
I'm not sure why there was 12v showing with one of the BMSs off. The mosfets should have been switched off.
Series BMS won't balance between BMS modules. Each 12v pack may be at a different state of charge. You will need to charge each 12v pack independently to get to get them at full capacity. Not an issue when discharging since the lowest pack will break the series chain, you just won't get full capacity out of each pack. You can't rely on them being perfectly matched over time.
Which is the same principle any BMSd pack operates under, you are only as good as your weakest cell
If u connect 2 48v 20ah batteries with 30-90A bms will the Amps double or stay the same?
Can I connect more bms to reach the 170v 200ah ?
no. even just 2 is risky, esp when even the Chinese tell you to not do that. More voltage = pay $ for a bigger or more sophisticated BMS. 32-40s
@@fvckyoutubescensorshipandt2718 I wanted to make a battery with 40s64p any suggestions on that? and thanks for the reply!
@@antiLeixo As long as all the cells are the close to same (ie same production run so similar internal resistance and capacity each) and balanced I don't see why not. Simply make 64P chunks and then series those and add a BMS that can handle it (both voltage and peak current). 40s BMS are less common than 32s, but Aliexpress has a few. I did find a 96s one there, but is only rated 30A and costs $520 (higher current options offered but probably thousands of $).
If you really think about it , if you take a normal drop-in replacement lithium iron phosphate battery Which Has its own BMS . The solar Community has been serious connecting in parallel connecting them With no issues so This is exactly the same type of test and so I don't see why there should be an issue. But again further testing Should be Considered before slapping something together
Thats a really good point. Almost all solar setups are now LiFePO4 batteries, ie they would have their own individual bms? And they are often setup as 24v or 36, 48v Even 52v- Now I just have to check what their batteries look like. Are they prismatic packs that they give one bms to- or plug and play units of 12v with their own bms? Cheers
question? what does the charge controller hook up 2
Cool
we need an explanation for what actually happens in series, I've tested multiple LED arrays in series. yes each LED is getting 3.2V but with some chips an overall voltage over 100V the LED'S can blow up when in theory they are getting the correct voltage and current. 3.2V and 350mA?
Almost found the video I was looking for. Great one non the less. Can anyone out there answer this question for me please. Is it possible to connect 2 50ah bms's to achieve 100ah's. I have a 12v 100ah battery. And have 2 of the 50ah bms's on hand. Thanks in advance.
After 4 years, he I am having played 16s for two years and now wanting to go 4x 16s to reach 192V for summer serious 5kW power to charge my EV. After reading a lot of the expert trying to explain the danger, I can see the point of body diode of the balancing mosfets… the proof was in your video. U started out with 26.27v no load, ie. 13.135v/ea. When the simulated disconnection of one bms, u got 12.03V. 12.03V is the results of taking out 4x Vf of body diodes @0.2763v/ea. This proves that the “off” BMS is bleeding through but luckily the inverter did the needed UVP that prevented high current flow to melt the body diode. This is discharging. During charging, I’m not sure, without actually having looked at a circuit diagram before, if the body diode will be reverse biased, and I suspect the mosfets are in series and so each mosfets will only see its own Vds drive from 13.135V/4…and this would still be safe?
and in the case of two lithium batteries of 36v and 70A each, can I join them to have a voltage of 72v without causing damage to the batteries or causing death?
SUBSCRIBED, great channel
I require some expert advice.
I am building a 12.8v battery using 4 x 38120 headway cells.
This will be used inside a car powering my project.
I would like the cells to be charged from the car battery/alternator but using low current.
The BMS says 50A and I was hoping for more 5A as can be plugged into the cigarette socket to charge or trickle charge the pack.
This way I can also fit some protection like a resettable PPTC fuse so when the project load requires high current, the fuse will trip and only current from the 38120 pack will be used.
Is this possible or does the BMS really require 50Amps?
Thanks
Where do you get that power meter? please give us a link
aliexpress, like everything else.
Hello, what about the charging? Thanks
Can i used 12*3 bms to 36 v for etc bike
To "remove" the load you could just have a switch or a relay?
How can charge for those BMS from battrey which volte i put to charge them ?
please try to charge it back ... doest it work ? thanks you.
0:53... I think what you said is reversed....
5:39.. Wouldn't it be better/cheaper to put the 8 batteries in series and use a single 8s BMS ???
Yes but that’s not the question I’m answering here
It shouldn't have shown 12V if one BMS tripped, that's concerning, can it still output any significant power at 12V after 1 BMS trips?
Check darren smith reply
Where do you get that power meter? The link on your other videos say that it’s sold out.
maybe if you use a third BMS to manage the 2 sets/batteries/BMS's Would that resolve or complicate things? Im on the shallow end with floaties on in this field. so just a thought and curious as to what would happen.
It's actually not safe to put BMS in series unless they are rated for it.
The Mosfets in each BMS are most likely only rated for 25v.
8 lifepo4 cells will be slightly higher than that.
Can I charge the battery in the same circuit as mentioned in the video with a 26v charge
Sir gehugarcia.nice demonstration of the powerful battery with bms..hev a one question for this battery. If have that kind of battery ,Can I use a solar panel to charge that battery directly or I have to use a DC to DC converter?
Hey what's the story with getting a European supplier for 18650
in that case you should add a battery balancer between two
would this work for a high voltage system where i need to connect 4 24s bms's in series to create 384volts?
Ah but can you parallel bms'? Inquiring minds would like to know. Two four cell bms on four cells to get greater balancing rates.
not sure if twice the balancing would work but you could pull twice the amps before they shut off
how to series bms with separate load and charge?