Full and empty LiFePO4 battery in parallel. THESE are the AMPS we're looking for! ⚡⚡⚡
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- เผยแพร่เมื่อ 11 ก.ค. 2021
- I'm doing some further development on the battery shelve, the MDF shelves do look much better now since I glued them together. Very sturdy and stable.
So, now it's time to prepare the battery. Before we start with that, I did some testing in regards to paralleling single cells. I was always curious to know how much attention we need to pay when doing this with the large capacity cells. How close does the voltage need to be before connecting them with beefy busbars. You don't want to have hundreds of amps running across, right?
Well, here is the test you were all waiting for 😂 Don't do it at home, this test is purely for scientific purposes... It's cool though!
The tester I have used to charge and discharge the battery (ZKE-Tech EBC-A40L)
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These are exactly the LiFePO videos you need, they also try things that no one else would test.
This is one of the most informative video experiments I’ve ever watched. I learned the importance of tightening the bolts. Thank you!
Hi Andy,
I really like your straightforward way of experimenting!!
As I’m interested in the explanation behind things, I did some calculations.
The two cells have an internal resistance less than .25mOhm. Assume copper bus bar length is 24cm in total with 40mm2 gives 0.1mOhm bus bar resistance.
If there wouldn’t be contact resistance, then for a voltage difference of 700mV between the two cells, the initial peak current would be 700mV/(2 x 0.25 + 0.1)mOhm = 1167A
The other way around: If your initial peak current is assumed to be 280A, then the total resistance is 2.5mOhm. Then your contact resistance is 2.5-0.6 = 1.9mOhm
So, your saved by having contact resistance addition!
Thank you.
Just one think, the voltage I measured was the Voc without load. Once connected the difference will be way lower.
You make these videos entertaining and educational 👍
I think a bigger problem would be 15 fully charged ones and one empty one.
Another Great Video Andy! Your style is the Best! The things we learn on your channel and the way you present it is unique! THANK YOU!
I appreciate that! Thanks a ton, Robert!
I think one take away if the affect of a loose connection on amps.
Nein!!!!!!!! Nicht kurzschließen... Wir brauchen dich und deine Garage noch..💥💣
Just catching up on your channel and I'm loving it. This balancing video caused me to want to reach for my own goggles! Keep up the good videos and information. I'm building a 1.5kW battery bank now for my EV and I like your simple explanations and demonstrations.
Andy, as always you never disappoint. Great information. Thanks
Thanks heaps, Bob!
Crazy crazy man! Thanks for your experiments. So very informative!
No problem, I always wanted to know...
Really enjoy these videos. The birds laughing was priceless.
Thank you 😁
Thanks Andy. Always entertaining and informative... Cheers!
Thanks Ken 😊
Great job 👍 I appreciate your work.You work very hard.
Good Idea I also plan to make my 2nd version of battery box.
The AMP's are strong with this one. 😎
🌑 Absolutely!
Thank you Andy, i've been waiting for this video. Now i can tell the installer to watch your video and follow your 4 banks in parallel.
Great test. I guess within the charge and discharge parameters. Great stuff Lifepo4
“Don’t do this at home”, you obviously do it in a garage!
Thanks for conducting this experiment, looking forward to the next one...
Haha, everyone is now expecting I will do something serious with the paralleled bank. That would be NUTS! 🥜
@@OffGridGarageAustralia You can perform an accidental tool-drop experiment causing a short-circuit. Will it weld itself to the busbar or not? That would be extremely educational, because soon (LFP getting darn cheap per round-trip kWh) thousands of people may be building these kind of DIY batteries. This type of accident happens all the time. There may be ways to do this experiment relatively safely using contactors with high enough interrupt current rating.
@@diyEVguy That's not good for the cells either. You can find videos online when people did that.
@ Johan. That’s why the process is called EXPERIMENT. Without experiments and positive results how can a system be enhanced, how can general public educate themselves, Me , for instance? Dropping a scanner on opposing terminals can happen to any one. It’s not necessary that the Author (Andy) has to drop it. I’m totally thankful to the author (Andy) for his thankless explorations and which is called EXPLORING THE UNKNOWN. The question remains unanswered, has any one conducted such experiments and was bold enough to make a presentation, like the Author? The answers to that is NO. So we watch n learn from a person who performs such intricate experiments , instead of a abrasive comments by people. Thank you for your views. Stay safe and 73s…
Thanks Andy, learnt something today and good test for those Aluminum link plates, passed with flying colors
These were all the copper busbars though which came with the cells.
Just brilliant, amazing you didn't get any sparks, and very interesting that the current only increased once tightened down, presumably due to the low voltage.
Hey Andy I figured out a super good product for all our battery builds that us diy people love so much..... rubber roof material. The black rubber roof material isn't expensive and is perfect for between cells and as a shelf liner. I'm finding all kinds of great uses for it around my place but especially with the batteries. It's not only a great insulator but it gives a cushion for when cells change sizes. If I come up with more usefull tips I'll let ya know. Thanks for the videos
Crazy man. Love it. Thank you for the education and th entertainment.
Thank you. Always a pleasure 😊
You made my day. Thank you, excellent work
Glad you enjoyed it!
Thank you for doing this! I've been telling people for years it's not an issue and to just parallel them, now there is evidence!!!
Ive done the same with 200 AH 12 volt batteries years ago , about 2 volts difference, same basic result, Andy's test showed about 140 watts peak power flow, 200A x 0.7 volts
Just be careful if you have several fully charged cells and only one is empty. That could go wrong!
@@OffGridGarageAustralia I would do it just like you did, not tighten the bolts right away, but come back an hour later. Easy :)
Nicely done again - good test.
Thank you 😊
Thanks Andy I really injoyed the video
Thanks Luke!
Earned my subscription with this one. You got balls of steel playing with batteries like that 😅
Amazing how much more current is flowing just by tightening the bolt nuts. 🤩🤩
Yes, I found this early when started building my batteries. These connection issues haunted me for quite a while...
That was a great experiment! I expected that to go badly, with well over 1C going from one battery to the other. Very interesting! :)
Thanks Jason!
@@OffGridGarageAustralia This also shows how CRITICAL it is to get your connections tightened down properly. Thanks again for doing this somewhat risky current to show what we need to be aware of with our battery cells.
Thanks as always Andy...helps me greatly to understand this chemistry. Buy ya a beer if you ever make it to this island!
Thank you!
Good work ! and we are happy that you still alive ... ;)
I'm very careful with what I'm doing 😉
I didnt know you were in aus . Kookaburras sound awesome . I had some 38120 po4 batteries that were drained to much and wouldnt charge so i got a fully charged one and joined it together for a little bit to bring it upto the voltage the charger would swith it on . It works but dont leave it on to long . The resistance in the ones i drained to much has come up . So they work and charge but are a little damaged they dont last as long now but still work . Once life po4 batteries are drained to far they get a pretty high resistance but still work . I mean i really drained some of them . Like 0.2 volts . They are only ment to be drained to 2v . They work still though .
Oh, that's bad. Why did you drain them that much? Was this an accident?
While doing this experiment, you should measure the voltage over the busbar and calculate the busbars resistance....
Absolutely! Next time. The new test cells have just arrived, so more experiments coming soon 😉
@@OffGridGarageAustralia did you get an email from SCA Express when the batteries arrived in Syd?
@@zzcfrank yes, an SMS first and they asked for my email then to send through the paperwork.
I need to order some of those cells. So many possibilities!!!
Yes, you should, they are amazing!
200 amps @ 3+ volts DC, remember 3,200 amps @ 16 volts DC! I always wondered how many amps a single 3.6 cell could produce! Thumbs up and subscribed!
Thank you and welcome on board. The cells can easily deliver several thousands of amps in case of a short. The 16p setup at the end, may be able to deliver clos to 80kA at 3V.
Interesting experiment Andy, suppressing the amount of compression you need for a solid electrical connection, also >200Amps flowing with only .7 Volts. Wow 👍
Quite scary, right? Imaging you have 48V and a bad connection.
That was fun I laugh so much my face hurt great thanks for the info and entertainment
Glad you enjoyed it, John. And thanks for the great feedback!
Ten ply wood , would work. You are have to much fun Andy.
I actually don't like the wooden situation at all. As per regulations, it should be metal.
@@OffGridGarageAustralia So regs ask metal aluminium checker panel? Can get expensive.
Good show brother! This is how I parallel mine, two different voltage and delivers. Ya it was no biggie. Took about 2 weeks to get to 3.5v . All ready to build the battery now hehe. Cheers Andy 🌞
Yeah, got all the material here now, so I'm getting ready.
Oh I thought you are going to parallel the 16S battery pack, got scared seeing the title! Good that you did the experiment with a cell.
I Will watch the Episode with empty vs. Full 48v battery.
Yeah, I will watch this episode too! But not on my channel 😊
Wow and wow again over 200 amps between 2 cells!
With all those cells in parallel, if you short the cells with a wire-wrap wire, you might cause the wire-wrap wire to explode just like an over powered fuse. Be very very careful if you choose to do that experiment. Spalling copper everywhere, use some sort of extension cord far away from the battery bank to the wire-wrap wire. Ear and eye protection.
I'm not doing any experiments with this batteries in parallel, that is far too dangerous. That was just a joke at the end of the video 🤡
@@OffGridGarageAustralia We did the exploding wire-wrap demo way back in my college days, while studying pulse power at the xxx amp level. It made for a great open house demo project. Completely turns the wire into a plasma arc... sounded like a M80 fire cracker. Scared everyone even the Professors, more fun then the 200k Tesla coil demo. Not a good thing to try without alot of preparation effort. Over charging a battery at a high charge rate by not balancing the cells first, frightens the crap out of me because there is alot of mass (shrapnel) to send flying across the room.
I am totally intrigued by your battery study efforts. Your doing great work!
Intéressant et amusant ! super merci.
Nice testing that was awesome
Thank you!
@@OffGridGarageAustralia I did that with my final row batts that daly bms got kina warm
Balancing these batteries means discharging one battery and charging the other.
You can charge a LiFePO4 battery with a least 0,5C. That means if you have a 280Ah Battery, 140Amps permanent should not damage the Battery.
Most Batteries can take a lot more if it's only for a short time.
If you want to balance them without having a lot of amps flowing, you can connect the two negative an then run a regular cable with a 12V light bulb between the two positive.
(positive battery 1 to positive of the light bulb
and positive battery 2 to negative of the light bulb.)
The batteries are balance if the light bulb is completely off.
It's a safe way but this could take hours.
great lab test.
Garage-Lab for the win!
Here's a suggestion:
Parallel the cells an then connect the charger to the opposite ends of the parallel pack (e.g. positive to the right an negative to the left).
This leads to every cell having the same amount of busbar in series to the charger - in other words: every cell having the same resistance when viewed from the charger. The current will therefore be distributed more to the empty cell with all cells reaching the same state of charge at the end.
If you connect the charger at one end only, the furthest cell will see a higher resistance to the charger and you will need more time and less current to balance them.
As shown at the end of the video ;)
@@OffGridGarageAustralia In that case, please ignore my comment. I thought I watched yur video till the end, but must have overlooked it.
@@r.igormortis149 that's all good. It's always good to have these comments and point out important things again, even I showed them in my videos already. It helps people better understand the basics. Thank you for that.
I love the big flat surface area for connector links to sit on, compared to miserable welded steel button sized seats on many varieties in early 2024.
The width of slots in links should be just 6mm wide as thread is fractionally smaller, so clears it. Thus gives you more contact area on terminal too. Supplied links are a cheap answer, not the best solution I think.
You could do some lovely arc welding with that entire bank..
Not a bad idea 😂
Great video.
Thanks, Bud!
LOL that's was real fun.... thank you.
It was for me too! 😂
I have done it with AGM batteries long time ago and the most I got flowing from 100% to 0% one was 10A 😌
Yeah, AGM have a relatively high internal resistance, so that helps as well with limiting the current.
MDF absorbs moisture like a sponge. Without sealing it with some paint or clear urethane or so will not see that last too long, they will start to sag in the rainy season.
All fixed.
(There is no rainy season down here 🙃)
@@OffGridGarageAustralia Well no clue of your location but seems in March rains & flooding - with evacuations where happening. Pretty sure it wasn't "Austria" ;-) either. But MDF absorbe humity regardless. Ever seen the Melamine Shelves warp & Sag, most are MDF or Particle Board. At minimum I would seal the MDF with a Proper/Sealer or something.
I would not want to see you place it, put it all together with the batteries and 6 months later be grumblig about it. But a litre of Primer is what $10 if that and two coats top & bottom of woud take likely less than an hour to do.
@@stephsoltesz6731 yeah, it's now been replaced as shown in the last video.
@@OffGridGarageAustralia LOL, Just watched that, 5mm Aluminum will certainly not be affected by weather and you have something much better now IMO.
A little suggestion, you may want a clear cover/door or something because any accidental intrusion into the "battery hot zone" could lead to a ouch, and of course kid/pet safety too.... I'd hate to see your gorgeous cat get zapped for taking a nap in a bad location... Also have to protect those precious frogs ! LOL
I learned to never say never, Mice made a nest on top of one of battery banks and it didn't take long, my cat is the one who "notified me" of their presence. Amazing how mice can get into things.
$20 says you can melt your spanner if you short it out on just one of those 280 ah cells! Another video idea!!!
$20... 🤔 I'm cheap, I'll do it!
Nah, just kidding, I'm NOT going to do any short testing here on the channel (for now).
@@OffGridGarageAustralia Well...not on purpose!
"Maybe I should polish the terminals again" LOL 😆
This from another channel think Joe's garage or something (Sorry if I got it wrong). He was referring to the troubles you had with bus bar at cells 6,8 I think. Instead he went with star lock washers instead of all the polishing. Would you consider using them on Pack 2 and 3. These would bite into the bus bar and not just sit on top.
Nice just installed 1200 amp hour 12v pack in our %th wheel..
Nice, lot's of juice!
How can 13 people dislike this video? This was great Andy!
1:48 My Neighborhood in Germany sonds just like That.
May I suggest that you use strings of leds as emergency lighting for the garage. You can cut several strips with the same number of diodes so that they draw equal current. Now attach across sets of 12 volt cells. They will only draw a couple of amps each at most. Your batteries are huge so this lighting will be a negligible draw. You can disconnect the garage from the batteries and still have lights.
Yeah, an emergence light setup... I have the Bluetti now and just forgot about it, could have plugged in the video light.
LOVE IT!!!😲💥🤘
Thanks, Joe 😊
Very good information but the most funny part of the monkeys laughing 🤣😂🤣
They are not actual monkey, you know that, right?
They are Kookaburras en.wikipedia.org/wiki/Kookaburra
All nuts. Really :-)
You need a serious clamp meter for further tests :-P
That was the best experiment ever, thanks for sharing ;-)
Thank you. I think 200A is as far as I want to go with bare cells...
a lot power you have mashalla
💪😬
Since watching your battery builds and balancing vids, somewhere I thought about what happens if instead of arranging the cells in a line. arrange them in a ring like the spokes of wheel with the busbars all connected at a central hub for the terminal connections. admittedly the outer terminals and busbars would form some sort of bridge sitting some distance above the central busbar connections. Admittedly with my car camping setup I am sticking with a solar panel 100w and a 110a 12v marine / leisure battery to run an electric cool box, but you know how it is after a spot you get to thinking about these ideas and would it reduce balancing problems during charge and discharge or is it a NO NO for other reasons other than connections. just a thought while you were being adventurous. p.s be careful. Might not be space effective either, dont know?
Arranging them in a ring is certainly a good idea for the equalization part when they are in parallel. On the other hand, the only benefit would be saving some time.
The level of excitement, especially when it went over 200 amps, is very relatable. I love that feeling when you want to try some "crazy" experiment and it works out just as you expected it to.
Yeah, I love that. It's so much fun. More to come...
Your battery bank is getting so massive I would almost consider using a liquid metal batt.🤓👍✏🗒😁
They are far to expensive though. And the FLPs are so easy to handle and operate. Not sure if you can get and equipment for DIY when using liquid metal batteries.
@@OffGridGarageAustralia I have no idea what I am talking about, but your batt. bank is insane 🤓. Awsome...lots of power 🔋😃
TH-camr ElectroBoom has competition...your insurance company will love watching these videos. LOL
A tip for your cell to cell bus bars. Put a piece of heat shrink tubing leaving about 20mm exposed on the end. A cheap little piece of extra insurance against shorts. Will also be a good idea for the main bus bars as well.
I always make sure they are covered when not working on them but that's a good tip as it minimises the area exposed.
The main bus bars in the shelve will stay blank as everything will be fully covered and you would need tools to get to them. Also, there will we warning signage ;)
Andy i was very surprised by the results you had in regard to the contact resistance of the battery terminals to the link bars, as a sparky by trade if we were terminating aluminum conductors to copper we would use a bi metal compound within the joint to maintain the joint integrity over time , I would be interested to know and what others think of how your results may differ and benefit with the use of this compound , a quick check will find its use is to improve conductivity, reduce aluminum oxidization within the joint etc etc .
I am really surprised nobody talks about its use and infact question why the links are not Aluminium ?
Thank you for your comment. There was a huge discussion about such compounds in previous videos.
Andy, I’ve been watching your progress and I am inspired to do my own mini off grid garage. I need some advice , I have at the moment 2 x 170 W panels, open circuit volts 43.8 . Voltage at Pmax 35.2 . Current at Pmax 4.83 A.
I have a VictronConnect 75/15 charge controller . If I connect the panels in series Is the voltage to much for my charge controller
Hi William, thanks for your feedback and question. Yeas, that would be too much for the charge controller. The 75/xx models are really only for 60 cell panels with a max of ~35Voc. You would need a 100/xx controller for that setup or put them in parallel for a 12V or 24V battery.
Nice test. It was actually slightly more amps than I thought. I thought maybe 5 or so.
A lot more than 5A. A lot...
Andy Frankenstein... ... Lifepo4 Monster, more power, more power, It will come to life...
😂😂😂
Since the torque makes a big difference, I'm wondering if the terminal contact area got hot. Likely not much, since the nuts seemed cool to touch.
Busbars just got a bit warm. As they are usually cold, it felt like maybe 20-25°C. I should have measured the temp 🤦♂️
Now thats some nice info. GJ on not dying lol :)
😂😂😂 Good test, had me laughing out loud,..
That's the main purpose 😂
the more dangerous it got with all that current flowing the more Andy was laughing i could not help but LOL. But in all seriousness dats some serious current from just two batteries yikes.
@@mannyfragoza9652 I know, it was so exciting to see these high currents. It was a fun video 😂😂😂
@@OffGridGarageAustralia i was blown away. but very exciting also
Daly has just developed a unit to control current flow between battery banks/ BMS units in parallel. It is not posted for sale yet but should be soon. I received a pdf file on the unit after asking Daly about this. Installs in parallel with an upgraded BMS and seems to have a resistive device that controls the current flow. Looks complicated and the same could probably be achieved with a differential circuit and cutoff contactor. Will send pdf file but can’t see how on your site.
Am new to all this, wouldn't the batteries in parallel just show the same voltage and each pair just balance themselves out?
Excellent experiment. It is just crazy how much power is possible. So if left for hrs how much capacity do you think is lost?more than 50%? Def cool test Andy I was giggling too
The more the nut is tightened the more current flow between the two cells. What would be the optimum torque to apply to the nuts for cells in an operational battery of cells?
That depends on the cells and should be in the specs.
I think if you did a short circuit test of 16 of those cells in parallel, there wouldn't be a next video :) I think if I were building that new battery bank, I'd work out exactly where each of the connections to the bus bars were going to be and heat shrink insulate everything else. I know you will have protection but still ...
Yeah, that short could exceed 50kA easily and would melt everything.
The bus bars can stay as they are as the shelve will be fully covered with panels after the build. They look too nice to hide them.
Just a though, DavidPoz, another DIY solar youtuber, to top balance his new batteries before paralleling, he charged them all in serial first. Serial keeps the volts the same just added their amp hours, right? So that should allow them to better top balance, or not? I would like to see how good or bad that is. Is it better at evening out the voltage? Or does it just fill their capacity evenly? Or could it even be both?
Series charging does not keep the voltage the same. If cells have different stat of charges you will likely overcharge one or several cells. Dave did this because they were already pretty balanced and they charge up a lot faster in series than in parallel. In my case, some were almost full some were at 50% SoC, so no way to series charge them before equalize them through a parallel connection.
So charging in series does not top balance them, it just charges them all faster. The same current goes through all cells at the same time while in parallel the current splits in the individual cells. Current is what is charging your battery. The more, the faster it charges.
Hi Andy, I accidently shorted my 4 x cell LiFEPO4 battery for a few seconds. I forgot to insulate my the wrench. It disintegrated the top half off the most positive screw thread. Everything looks ok, but I am wondering if I am in for trouble with these cells now or should they still be ok?
Disintegrated... what does that mean? Has it popped out?
The cells should be fine but keep an eye on it through the BMS when you charge and discharge it.
What’s you’re thought’s on combining 2 lithium battery banks together both are 48v but 1 - Bank is Lithium phosphate 280Ah & bank 2 is LTO Titanite 40Ah Both have Daily 120A BMS’s and the Daily Active Balancers ?
aside from the issue of initially connecting the batteries, i thought the main issue of unbalanced cells would be for ongoing charging.. and usage,.where the weak call would draw more and a full cell would be used less. visversa during charging. dunno
This is only in a parallel setup though. In series it is different and your whole battery bank is only as strong as the weakest cell.
@Off-Grid Garage... a little off topic... but did you get an email from SCA Express when the batteries arrived in Syd? Otherwise keep up the good work! very inspiring :)
Yes, they send an SMS first and asked for my email to send the paperwork.
Andy, that's only if you are paralleling two or three cells. Every cell you add to the parallel group is a knock-on addition to the amps, scaling linearly. So if you put more than a few cells in parallel and one of them is discharged, you can easily start a fire.
-Matt
Yeah, but only if you would order them accordingly from the highest voltage to the lowest, the current would flow in one direction from one site to the other. Usually they are mixed for the equalization part and the currents will balance.
But yeah, if you have the situation of having a lot of full cells and only one empty one, that could be a problem.
Great to see this channel giving a answer for the questions in the minds of DYI geeks
Andy. When are you going to replace the plug on that jigsaw? 🤣
Never, that's the only real plug. The Aussie standard is so 60s...
awww no magic smoke 🔥😂
I was cautious to NOT getting any. Imagine the current is welding the busbars to the terminals... 💥
071221/2132h PST 🇺🇸 Sad to say, people are weaning out of Li-Ion Cells (18650/26650 etc etc) and many experimenters, cell assemblers are pulling their aforesaid assembly and replacing with LiFePo4 cells, for obvious reasons. Presently there’s a glut of these Li-Ion cells and they are being sold at ridiculously unbelievable low prices.
The author (Andy) knows his job thoroughly than 90% of the YT Warriors and his mirth shouldn’t be misconstrued as accidental slip of spinner or shorting out 280Ah Cell. The Author (Andy) REALLY REALLY fooled me at a stunt where he started weeping (spraying H20) on face and did a fantastic crying session. I was like awww poor Andy ! he fooled me. So beware more of such dramatics are to arrive in future. Bless the man. Stay safe and 73s…
They say you should never parallel batteries of different sizes.
It would be interesting to see your 280 & 100 Ahr batteries paired up and run through a parallel discharge. Then an individual charge to confirm each capacity.
Does one get drained first ? The voltage must remain the same so does this control the rate of discharge ?
I'll do this soon. There is no problem of paralleling different capacities and charging/discharging them.
@@OffGridGarageAustralia Thanks I look forward to that. I could not see a problem, but everything you read on the web says not to.
Just looking at your charging figures in respect of the balancer, they are very useful.
At 49.5v with 1Ahr, voltage difference 16mV.
At 54.4 the same 1Ahr gives 208mV deviation.
At 48v the same 1Ahr gives an astonishing 1136mV deviation.
No wonder the balancer corrected so quickly.
You exposed what a terrible connection those buss bars make . It would be interesting to test bare copper , bare aluminum , etc .. Amps versus torque. I never have liked the idea of tinned buss bars , at least at the terminal connection.
Great idea
I agree. A quarter turn of a nut on any lug or busbar can have significant effects! Proof right there! Then multiply that by a dozen or more connections spanning any bank, and boy howdy!! How many times have I seen "re-check and re-tighten all connections" to troubleshoot discrepancies? Many!! I don't think it can be proven any more clearly here!! Great vid Andy! I will type "lol", but I really do laugh out loud watching you move along with your experiments! Thank you sir!
can your charge discharge to be used on 48 v battery?
You need to knock the coating of those Buss bars at the connection points
Never heard of that before... Is anyone doing this at all?
You should built a full plenum for those shelf bus bars. Just before you add anything else! You'll thank us later.
Why should I do that? The whole shelve will be fully enclosed and panels cannot be taken off without tools.
Hey Andy, Imagine 15 fully charged, and only 1 discharged. 15 * your 40amps = 600amps, and one potentially damaged cell
That's not how it works.
@@JM-yx1lm If they are all in parallel that is exactly how it works. If in series then no, just way un-balanced. It's standard procedure to put them in parallel to balance first. If you do that, and one cell is discharged while the others are charged you'll have a surge of current that will far exceed the 1c charge rating of a single cell.
Yes, that could be very dangerous and could start a fire. You can never be sure how full they really are if you just measure the voltages. I'll talk about this (and show) in one of the next videos.
@@OffGridGarageAustralia Rght that flat voltage curve between 10% and 90% doesn't tell us much about the SOC :)
So in summary, approx 1C - good to know.
Yeah, only in this extreme situation. 200mV difference is not an issue...
What would happen if you were paralleling 16 cells that you thought were all full but the very last one you connected was near empty?
You always need to measure the voltages before paralleling the cells. I'll do another experiment soon.
Even 150 amps would be just fine for the size of cells you'd have to be over 280 to even be one c and that ain't really that bad
Rating is 1C for these cells and 2C for a few seconds.
Seems they take or charge at significant less amperage than they are rated for. I would have expected 280 amps.. mine on a 30 Amp charger never take more than 23 amps. What am I missing?
Excellent experiment. How about fully charging these cells individually and then connecting them see there is any circulating current?
I have 9 lifepo4 100A batteries, I want make 24v battery pack. So can I make 2 batteries in parallel and other 7 in series?