I doubt the overpressure on bad cells did any appreciable damage to the others in the stack. My experience says that the pressure window is pretty wide. Why pressure? on pouch cells when you charge the electrodes experience intercalation damage as the ions "squeeze in" to their parking spots which literally breaks apart the structure. This is also why charging to 100% does a lot more damage than 80%. Having the pressure helps mitigate this somewhat, but doesn't stop it. Also as soon as this happens it also disrupts the electrical path, which reduces current carrying capacity thus raising internal resistance, preventing the cell from delivering as much current, and also causes it to make more heat, which accelerates the damage.
Pressure is not "required" for a pouch cell to work. In fact, look at phones and laptops, they usually just have a pouch cell shoved in there. (They use different chemistry to help ameliorate this damage, but it still accelerates) Charge a laptop/phone to 100%, let it sit in the heat, and it lasts only a few years before there is a marked reduction in capacity. Keep forcing 100% in there every time, and eventually it breaks down enough to become a spicy pillow. The best thing you can do for non-constrained pouch cells is NOT charge to 100% everytime and not let them sit there. In addition to my EV, I charge my laptop and phone to only 70% daily unless I know I will be needing more. My phone and laptop still have about 99% SoH (health) even after 2 years. My car is only down about 10% after 8 years. (Mostly calendar degradation) If you insist on charging to 100%, then you definitely can use pressure. I think it would take a huge overpressure to damage the cells too much, they are pretty dense, so I think there is a wide range, as long as you have enough to help keep the electrodes from literally falling apart. What will help more than pressure is keeping it at or below 4v/cell on the high side and 3v/cell on the low side, especially for lawn equipment that sits a lot. Yeah, you lose some usable, but then you'll get an order of magnitude more life out of it. This is especially true if it lives in a hot garage. On Fri, Aug 7, 2026 at 8:16 AM Mr. Sharkey via EV <[email protected]> wrote: > > On the topic of cell swelling... > > Bill (and all); > > Having just undergone an extreme pressure event, now I have to wonder > if this has been damaging to the eight modules that weren't/aren't > swollen, but were in the same containment with the two modules that > did swell and produced the pressure? Nothing ruptured, and aside from > some of the thin aluminum casing being a bit deformed, everything > seemed to relax when the pressure was released. > > Still have to do a complete set of voltage readings on the remaining > "good" cells, I intend on watching them carefully for a period of > time before I get too comfortable using them again. > > _______________________________________________ > Address messages to [email protected] > No other addresses in TO and CC fields > HELP: http://www.evdl.org/help/ > OT: If you use an Android device, please read https://keepandroidopen.org/ >
_______________________________________________ Address messages to [email protected] No other addresses in TO and CC fields HELP: http://www.evdl.org/help/ OT: If you use an Android device, please read https://keepandroidopen.org/
