Gen2 Volt cells puffing

[Mfabricator]

Hi all, I bought a gen2 Chevy volt module thats 2p 16s. Due to my bikes space limitations I have to remove from the housings and will not be using the chill plates. While restacking them and clamping the tabs I noticed that they are a little more puffy than I feel comfortable with. It seems if I give them compression of any amount I will be clamping air more than the core, this may be partially because I live at a little over 5000ft elevation. The cells are from a low mileage 2018 model and show no signs of any self discharge. How dangerously sinfull would it be to put a pinhole between the tabs in the expansion zone at the top, and then seal it up after compressing lightly and allowing gasses to escape? Also what gasses would they be? TIA for help and insight.

 

[DogDipstick]

Dont do it.

It sounds like you got some puffed cells. They do eventually puff... they have lost capacity at this point too. If they hit zero v per cell they puff up slightly. Some shady sellers will get a module at 0v and try to recharge it. This p[uffs them all a little bit equally. You can try to discharge them to 3.0v per cell before wrapping them up ( volume of gas less) but it wont help much. I know what you are dealing with. they dont stack nice, they sit wobbly, they wont compressevenly. I wont build with slightly puffy cells. i give them away. I never tried to poke the gas out of one of them.. ( old myth from rc days that you can " unpuff" a cell.. with a pin and tape... ) .

Yes, a lightly puffy cell still holds 13 of its 15 OEM amp hours... or less.. but it wont register full capacity on te log. They are compromised and done IMO. this is one of the things you must look out for when buying used, sight unseen.

....


look at this cell. It has VERY tight pouch around the tab.

 

[eMark]

Correct me if wrong ... Those cells will not PUFF IF not abused. My definiton of pouch cell abuse is when a cell shows signs of swelling and obvious puffing. Likewise same for RC Lipo pouch cells as for EV pouch cells.

Yes, it could be a defective (B-grade?) cell when only one of the pouch cells in a pack shows signs of swelling/puffing. Part of the conundrum is arriving at a consensus on what is and isn't abuse. It may be that the pouch cell(s) are nearing or at its EOL causing one or more pouch cells to swell/puff. Due to what is now "abuse" that an EOL or defective pouch cell can't endure.