You will probably get the ridiculous numbers folks get from using the wildly inaccurate round cell chargers. Nonsense like 150mOhm or up near there.
I didn’t measure the IR for the 35E but it’s around 35-55mOhms, probably more towards the higher end of that scale.
The actual numbers you get in testing, and how many cells you need vs how many you have, will probably guide you towards what limits to set. If they are almost all measuring 3300-3350mAh and only a few at under 3000mAh then it’s easy to pick the ones you will keep. Same for the IR readings.
But if you get an even distribution of cells from 2000-3300mAh (doubtful, but let’s pretend) then what you will accept will probably be determined by how many cells you need out of the ones you tested.
Most “ah shit!” moments I’ve had were from taking packs down to salvage cells. Generally, I don’t do it anymore. But yes, damn that is a time consuming, anxiety inducing activity if I’ve ever seen one.
Tbh, I’ve only broken down one pack in my life and it was a massive PITA. I’d never do it again if I could avoid it. The money savings are completely wiped out by the amount of time and effort not to mention hazards inherent in salvaging cells. Imho I would just wait and save some money to start w new cells. Especially if you’re newer to building packs.
Edit- I realize that wasn’t helpful or constructive
basically what happened is a friend of mine gave me a ton of old packs (each different levels of broken) and said he would pay me to fix them up for him (he said he works for a place where they have hundreds of these packs) and would pay a reasonable amount for me to salvage them.
this also is experience at battery building for me and i wanna get some good experience and then possibly start a battery building service.
thats the reason atm i would basically do it for free if you cover costs of cells.
just looking for experience
i get you though and hate taking apart packs… but someone else is paying
Ya buy some sand. If those packs are damaged there’s also a chance that one of them could short while in your possession. I wouldn’t take more than one at a time if I were you and make sure you store it somewhere that’s fireproofed.
Potentially overkill in thinking, but couldn’t a metal container get hot enough depending on the severity of the fire to ignite things around the container/what it’s sitting on? Or do the cells not put off that much heat.
IMO, no.
But for me everything is always on a non-flammable surface as standard procedure for anything battery related.
I guess that once the cell stopped moving around and sat on the bottom it might heat up the metal container at that point but I don’t know how much. The cell would be hot but most of the heat will have been sprayed out.
I use metal containers for emergencies but since someone might drop a suspect cell into one without a wrap on it, and maybe short-circuiting it, I deleted my comment. A cell in runaway though will have no additional issues being in a metal container unless, possibly, something heat sensitive is below where the cell comes to rest.
So, the bottom line is don’t do what I do. Use a sturdy non-heat-conductive container that can withstand a pressurized spray of molten aluminum and flaming electrolyte, can contain a cell rocketing around inside, but still let out the gas/smoke.
Use a sturdy non-heat-conductive container that can withstand a pressurized spray of molten aluminum and flaming electrolyte, can contain a cell rocketing around inside, but still let out the gas/smoke.