Battery Hookup new listing “Case 100x 3.3v 2200mah - 200x 18650 Lifepo4” for $100.00 + shipping

[eccerr0r]

It is no doubt rust, but not caused from water coming from inside the cell (because there is no water inside the cell unlike alkaline or lead acid batteries). Likely you also got a pack that had water intrusion but not as bad as the one I got. Capillary action can explain why the rust appears to show up around the heatshrink.

[sam_sam_sam]

It is no doubt rust, but not caused from water coming from inside the cell (because there is no water inside the cell unlike alkaline or lead acid batteries). Likely you also got a pack that had water intrusion but not as bad as the one I got. Capillary action can explain why the rust appears to show up around the heatshrink.

I would go long with this explanation if it was not using fish tape that is covering the tabbing ends on the crimp end of the batter cells and only one that is facing the same way and the fish tape is not easily removed to inspect each battery cell so I am still confused by this explanation

[eccerr0r]

The PSA did protect the side that was stuck to it looks, and capillary action accounts for much of the rest.

Unfortunately I can't make any judgments on the chain of events but the batteries were probably water logged before packaging.

Incidentally if it really was brown electrolyte versus just rusty water being sloshed around, that electrolyte would be a lithium salt and those are polar. Polar salts should readily dissolve in water like sodium chloride, unlike iron rust/iron hydroxide which is poorly water soluble (but more so if the liquid has low pH). If you have a water wet towel, lithium salts should readily dissolve, but if it requires acid then it's more likely iron rust.

[sam_sam_sam]

The PSA did protect the side that was stuck to it looks, and capillary action accounts for much of the rest.

Unfortunately I can't make any judgments on the chain of events but the batteries were probably water logged before packaging.

Incidentally if it really was brown electrolyte versus just rusty water being sloshed around, that electrolyte would be a lithium salt and those are polar. Polar salts should readily dissolve in water like sodium chloride, unlike iron rust/iron hydroxide which is poorly water soluble (but more so if the liquid has low pH). If you have a water wet towel, lithium salts should readily dissolve, but if it requires acid then it's more likely iron rust.

If this is the case then there is a quality issue when they were processed if this is the case might explain why this only happening on certain battery cells so what is the solution for the ones that are showing these symptoms that is depicted in the picture above with pure water and then dry them fully or is a better solution for this issue

[eccerr0r]

So have you proven what the brown stuff is?

Is it rust or some electrolyte residue?

I venture it is rust from the tabbing or contacts oxidizing and washing away and luck of the draw that cell got the water.

[sam_sam_sam]

How do I prove which one it is

[eccerr0r]

First use a water wet napkin or paper towel. if it's easy to remove, it's could be a lithium salt but I thought most lithium salts should be white colored as it's not a transition metal.

Then use vinegar. If it's easy to remove with vinegar, then it's probably rust that came from the rusty tabbing.

Lithium ion batteries use some sort of lithium salt as the electrolyte mixed with a VOC to make it liquid. A common li-ion electrolyte salt is LiPF6 which should be white and is water soluble. Again water is not used as the solvent inside lithium batteries because there are free lithium metal atoms around, so a VOC is used instead. That VOC dries off fast.

[sam_sam_sam]

I will try water first and then vinegar and see which one cleans the mess off of it

[sam_sam_sam]

Here is a picture of the battery cell that has the most signs of leakage with the plastic disk removed and the paper towel was dampened with water and it cleaned most of it off of the battery cell crimped end

[eccerr0r]

Yep, looks like water intrusion because the case (steel) is rusted.
BTW when I say "easy to remove" I mean it doesn't need scrubbing, just like when one wipes up table salt or sugar, the crystals just "melt" into the paper. TBH I don't use vinegar to remove rust, I use hydrochloric acid and iron oxide rust likewise dissolves into the acid/paper into a liquid (though this is a chemical change instead of a physical change - the iron oxide (only slightly soluble to insoluble) will react into iron(III) chloride which is soluble.)

[sam_sam_sam]

This might be the case IF these battery packs were used in air conditioned computer because I know for a fact that they keep these rooms extremely cold I understand why but if the environment where these battery packs are stored is extremely cold would explain this but why only some of them are showing symptoms like this

[eccerr0r]

Remember you aren't the first owner, these things have been around for 4 years before you got them!

Also keep in mind that the period where they were removed from service, and put into BH's warehouse, it may well have been outside for a while and it still could have been luck of the draw which packs were outside, on the bottom, underneath a roof overhang during rain, etc., etc.

The corrosion you saw with that pack is worse than the corrosion i saw with the second pack I opened... but clearly a LOT less than that first one!

P.S. I hate my camera phone, oh gawd this photo is so much better than what I can do with my stupid camera phone...sigh.

[sam_sam_sam]

From that picture perspective I would agree with you that it might have been in water at one point in time but I just not use to seeing bright orange rust I am use to seeing a more brownish orange color

[eccerr0r]

Given a thin enough coating, rust will indeed appear orange, though it is still dependent on how it reacted with the iron. If allowed to sit for a long time yes probably will get more brown rust but if agitated you'll get orange rust. Not sure if you saw a fresh rust spot on cars with paint damage, it's always orange-ish... I suppose the galvanization has a role though.

[sam_sam_sam]

Stay tuned more to come on this topic right now I am doing some testing on a boost converter that I also have a post about that I just updated today