Cells physically swelled, popped bus bars - are they fried??

mpickus

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Nov 25, 2020
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I purchased
4PCS LiitoKala 3.2V 280Ah lifepo4 battery DIY 12V 280AH rechargeable battery pack for E-scooter RV Solar Energy storage system
x2
from Ali Express. Took over 2 months for them to arrive. Configured them in a 12V 4s 2p arrangement with a Daly BMS and am using a Renogy 100 charge controller. The setup seemed to work but then the cells began to physically swell (even thought their individual voltage never exceeded 3.4 V). Swelling cause the busbar to pop loose (see photo). Are these cells fried???? If so were they faulty or did I do something really wrong?SwollenLiFePo4cells.jpg
 

Short_Shot

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This is why its recommended to "compress" the cells together in a pack. Specifically to prevent major swelling, not correct existing swelling. I am not the expert on what can be done at this point however.

How were you measuring the voltage?

its possible you overcharged them despite never reading anything over 3.4v, depending on how you had things set up.
 
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Alkaline

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Looks like the were put in a very hot environment, Temps kills lIFEPo4 faster than anything else.
 

Bob B

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It looks there were several things wrong ....

No compression.

Slots in the bus bars instead of holes.

Gonna be impossible to torque those screws .... should replace with studs / flange nuts.

Can't tell for sure how the bus bars were stacked, but they should never go from the top on one cell to the bottom on the next cell.
 

mpickus

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Nov 25, 2020
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Linky no worky.

How is your pack wired up? Are those 4 wires in the bottom right on the main negative terminal?
Here is how they were wired up. Yes those 4 wires are on the main negative terminal?
It looks there were several things wrong ....

No compression.

Slots in the bus bars instead of holes.

Gonna be impossible to torque those screws .... should replace with studs / flange nuts.

Can't tell for sure how the bus bars were stacked, but they should never go from the top on one cell to the bottom on the next cell.
Thanks. Bus bars were stacked correctly (not top on one to bottom on next). Is it too late to compress the cells and replace bus bars with holes not slots? Is it likely that the cells are now fried?
 

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Bob B

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Thanks. Bus bars were stacked correctly (not top on one to bottom on next). Is it too late to compress the cells and replace bus bars with holes not slots? Is it likely that the cells are now fried?

I'm not the expert in that area ..... I have seen posts saying that once they are bloated there is internal damage that makes them dangerous ..... I have seen other posts saying to put them under slowly increasing pressure and see if they can be normalized.

I would err on the side of safety and wouldn't consider these safe any longer.
 

jtvt

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Feb 11, 2021
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Are all the cells swollen? Any way the busbar came off prior to swelling and the swollen cells then were overcharged since it was no longer a 4s bank?
 

Diysolar123

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Feb 28, 2021
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Definitely were never put in a hot environment.
a hot environment also includes self generated heat from over voltage/currents...
4 or 5mm of swelling is a lot, that is wayyy over that from that picture.

so, yes they were overheated and, sadly, they should probably be properly disposed of.
 

NwCali

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Apr 27, 2021
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I say wait the required 9 months till they birth their little ones and hope the swelling goes back down...

At the least, hope that made you smile.

I'd not trust them myself. I have a ex you can send them to though. :)
 

Boondock Saint

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They're not workable now so you need to execute a plan B for more cells to get your show on the road.

Aside from that, if it were me, I would slowly discharge them down to near depletion. Once there I would compress them slowly over a period of time. If after a period of time they don't leak, have the right resistance etc then while under that compression (in a safe place) I would very slowly charge each individually again just a smidgin at a time. It could be that despite the obvious deformation, the packs are still viable.
 

Alkaline

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Also you can take them to local gun range and put them out of their misery.
 

newbostonconst

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I will get rid of them for you.....and pay the shipping....where are you located. I am in Michigan..

Thanks
 

NwCali

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They're not workable now so you need to execute a plan B for more cells to get your show on the road.

Aside from that, if it were me, I would slowly discharge them down to near depletion. Once there I would compress them slowly over a period of time. If after a period of time they don't leak, have the right resistance etc then while under that compression (in a safe place) I would very slowly charge each individually again just a smidgin at a time. It could be that despite the obvious deformation, the packs are still viable.
Find a golf cart that needs new batteries...my local scrap yard has one of those ford EV's for sale. Then when they go boom you want loose your home...
 

mrzed001

Voice of reason
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Apr 10, 2020
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Location
Hungary - EU
I purchased
4PCS LiitoKala 3.2V 280Ah lifepo4 battery DIY 12V 280AH rechargeable battery pack for E-scooter RV Solar Energy storage system
x2
from Ali Express. Took over 2 months for them to arrive. Configured them in a 12V 4s 2p arrangement with a Daly BMS and am using a Renogy 100 charge controller. The setup seemed to work but then the cells began to physically swell (even thought their individual voltage never exceeded 3.4 V). Swelling cause the busbar to pop loose (see photo). Are these cells fried???? If so were they faulty or did I do something really wrong?View attachment 58077

OK lets investigate :)
Here is a (not so small) questionnaire that is a base to analyse the battery failure and to point out potential problems:


- Cell compression, method? In your case cells not compressed. Not ideal but can work. Cells breathe so at 100% SoC bloat a bit and then when SoC goes down so is the bloating.
- Cells setup? In your case you did a 2p4s setup (2 parallel and then 4 times this serial). Not ideal but can work. BMS only saw the average V of two cells.
- Did you do a proper top balance of the cells ? What were your procedures, how did you do it ?
- Copper busbars on alu terminals. That is not ideal at all. Did you use noalox or carbon grease ? Terminals polished ?
- What was charging the battery ? MPPT or PWM solar charge controller or an utility charger? Size, Type, connected solar panels number, Voc, Vmppt, Amppt ? Charging settings (bulk V, absorption V, float V, max charging current) ?
- What was discharging the battery ? Inverter (size, type?), direct load ? Max discharging current/watt estimate ?
- Cells electric separation? Standing on a non conductive base? Non conductive separator between the cells ?
- Cells placement? Shed, garage, inside/outside? On the ground, on shelves, ... ? How protected from fauna (rodents, bugs) and flora ?
- Ambient temperature? Cells and busbars temperature in high load/charge (hand test not warm is OK) ? Any extra cooling like fans ?
- Humidity? Pipes near the battery, MPPT, inverter? Possible water, steam or condensation in the area?
- Cable size/type to BMS and after that? Fuse after BMS, size?
- Usage of the battery? Constantly charging, lot of time on max charge (SoC >95%)? Lot of time in minimal charge (SoC<10%)?
- Where the battery floated? So SoC >95% and float V > 3,4-3,45V/cell ?
- BMS is Daly. Which type, how many A? BMS still working ? Cell Volts in Daly the same as by measured with a multimeter?
- schematic diagram of your system would be appreciated (maybe some pics from it and from battery).

If you give the answer to this questions maybe ... maybe we can point out things that could cause your battery to fail/bloat.
So for the next battery you build you could change it and enjoy your battery for a long time :)
 

HRTKD

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Apr 24, 2020
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Somewhere South of Denver
The slotted end of those bus bars may have kept the cells from really tearing themselves apart.

There are too many cables on those cells. What is the purpose of them? The balance leads I understand. But what is the big black wire going to the middle cell?
 
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