A battery in my pack appears to be corroding

Went to remove my pack from my skate. Noticed one of the cells is corroded and sort of wet looking. I know this is bad. What the heck do i do? Still in shrink wrap so not overly exposed to air. But fairly worried at this point… Help?

Take it out now

Ok. Any pointers?

Remove the bms, then cut the nickel strip holding that cell in the pack

I wonder if the cell vented, corroding the casing…

this connection seems to be easy to remove without destroying everything, disconnect it and measure the voltage of the single cell

What’s the cell layout on this pack

If it vented it would’ve been towards the middle of the pack, would see crap everywhere

10s 4p flat pack. This cell is on the first pack where the negative wire comes out. It’s hard for me to answer as i didn’t build the pack.

The dude who built it figures it’s venting. I wonder why? Haven’t used the board for at least a month? Was just going to discharge to a safe storage voltage when i saw this.

It’s not too hard to remove and replace if you don’t mind soldering

If it vented there would be residue everywhere, ide say more likely a microscopic hole that is leaking. Also if it vented it would be bringing the whole P group down

Cool. Thanks for the info and the help guys. You guys are all right.

What cells are these?. Noticed i says “Tesla” on them, wonder Where you got them from…

3550mah rated capacity as well…

These cells are pretty much the same as SANYO NCR18650GA cells. The guy who built the pack actually purchased a Tesla D90 module and removed all the 18650’s. The wrap he added. They’re a high capacity lower discharge cell. The best thing about them is the longevity. They’re rated for 2000 charges. That is, when they aren’t leaking haha. Interesting to see how that happened. I would recommend a 5p config to have a higher discharge pack. Although i didn’t really notice much sag in the 4p config. Would really like to do a comparison with 30q’s of the same build to see the real time difference.

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Scary pack, there isn’t any insulation between your parallel groups? If they used acid based silicone that can cause corrosion. Residual flux can also cause problems.


I think I see those red paper 18650 insulation caps in between the groups, though it’s still VERY close to each other.

@Lionpuncher only rated for 2000 charges on Tesla equipment I’m sure. With the amps we pull and our charge and discharge usage, it’ll likely be on par with other popular market 18650s. I doubt these are rated for much discharge too.

@chaka: The guy who built the pack has built packs before, but this was his first flat pack. I know you had a thread on cell level fusing, do you have anything on general safe battery build practices for flat packs that i could refer him to? I ask because im giving it back to him for repair. Would really like to be able to reference some threads with safe practices. I’m sure he’d find it valuable as well. Probably many would praise those efforts. Apologies if they already exist. @Jinra, you’re most likely correct. One can’t deny they’re a great quality battery, but probs so are all the standard ones we tend to use. They have a constant discharge rate of 10amps and can handle 20 amps continuously for bursts of up to 20 seconds. I never put that to the test. Keep my bat max at 40.

Tell him to come search this forum. I have posted plenty of information through the years. At least make sure vibration isn’t going to wear through such minimal insulation.

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