openinverter forum

The back story:
Well I rolled the dice and bought an 85kwh model S pack off facebook market place.
It was taken out of a car that threw a battery error of some sort, and then a local EV shop swapped it out for a newer 90kwh pack (or so I'm told anyways).

However, I found out after the money had already changed hands that the shop who swapped it usually rebuilds the old packs, and this was the first one that they took a pass on. Apparently it had already been tampered with by some person that was "known" to them.
So it stands to reason these modules are going to be in bad shape...

I dismantled the pack tonight without issue, and the 16 modules are now in my garage.
I don't know how to connect to the BMS boards yet so all I know so far is that they all read 22v
(I will be reading up on module testing this week while I'm on Vacation)

TLDR - The Question:
It looks like the pack must have had a small leak at some point that allowed a small amount of water in, which then condensed on the surface of the modules. As a result, most of the modules have some rust on the tops of the cells,.... ...and one module has this white stuff on this corner: Should I be worried from a fire safety perspective?
Is this module more likely to catch fire spontaneously ?
Is there anything I can do to sleep a little better and feel confident that these things wont spontaneously catch fire?

Measure the module voltages.

tom91 wrote: ↑Sat Jul 13, 2024 12:11 pm Measure the module voltages.

They all read 22v.

Also I slept exactly zero hours last night....
... I am contemplating abandoning this whole project because the idea of having a battery fire is weighing on me pretty hard....

Thats okay, write the voltages down on them. Then measure them every few days.

tom91 wrote: ↑Sat Jul 13, 2024 12:17 pm Thats okay, write the voltages down on them. Then measure them every few days.

What about the rust and the white stuff? No cause for concern?

What rust? Can you post more clear pictures?

Are all modules like this, it looks like it might have been a coolant leak. Those modules are not to be used in anything as they might have self discharge going on.

It looks like the white stuff is left over drywall from poking a hole through. It's odd that it looks to be on top of the battery cover. Is it dusty, greasy, silicone like?...
The rust is sketchy. A close-up would help.
What are you trying to do with these? If you're swapping out rusty cells pull them now.
Do they all look this bad?

jrbe wrote: ↑Sat Jul 13, 2024 6:25 pm It looks like the white stuff is left over drywall from poking a hole through. It's odd that it looks to be on top of the battery cover. Is it dusty, greasy, silicone like?...

Yeah its weird, Its on top of the cover, but also seems to be inside the pack as well on that corner. I couldn't tell if it originated from inside our outside the module. It reminds me of a little of some kind of spray foam insulation from home depo that comes in a spray can that you would use to fill in small gaps and cracks etc. Or maybe some kind of glue..

jrbe wrote: ↑Sat Jul 13, 2024 6:25 pm The rust is sketchy. A close-up would help.
What are you trying to do with these? If you're swapping out rusty cells pull them now.
Do they all look this bad?

So 6/16 seem to be okay (no rust or other oddities).
The other 10 have varying degrees of rust on the tops of about %10 to %30 of the cells.

After reading a few posts about how 18650s can be dangerous if there is corrosion + moisture, I ended up moving those 10 to some boxes on the front yard, as far away from everything else as possible, and started giving them away to anyone local that might want/need one.
Maybe thats an overreaction,. Im not sure,. but I have decided to err on the side of caution here because I need to sleep and dont want to risk anything happening to my house.

I didn't realize it was possilbe to swap individual cells out.
Is there a write up or video available on that somewhere?
(Not sure I would actually attempt that, but would be curious to see)

I think reading posts like this one are curing me of any trace of interest in attempting to salvage or break down a module:

I have disassembled 5 modules now. My first attempt was mechanically, and didn't work. I accidentally nicked a cell with a Dremel. I was trying to remove 2 of the 6 series cell blocks to make some short custom modules and gave up do to the catastrophe that happened. I had a fire that lasted for 90 minutes of roman candles, skyrockets and pinwheels. Thinking that water would not help a Li fire, I used LithEx—5gallons of it—to no avail. The cell fires kept propagating to adjacent ones. With hindsight, water would surely have cooled the adjacent cells and stopped the propagation.

https://endless-sphere.com/sphere/threa ... ted.85401/

Tesla Battery Module Teardown 1:
https://www.youtube.com/watch?v=0BOkpkWypmc&t=668s

Tesla Battery Module Teardown 2:
https://www.youtube.com/watch?v=nMNCN6nlTso&t=460s

For anyone interested, I found some great videos on the Tesla Model S battery pack, and the causes of the water ingress problem:

Tesla Model S Battery Pack Basics:
https://www.youtube.com/watch?v=P7GR5fERXNY
https://www.youtube.com/watch?v=bNd-yJtRPhk
https://www.youtube.com/watch?v=izUl28YtQbE

Tesla Model S Battery Pack Water Ingress:
https://www.youtube.com/watch?v=_Vd4Is5QFME