Will NiMH cells do this?

My trusty Sofirn C01 stopped working, so I went to check on the cell, which was an Amazon Basics NiMH cell. I had a hard time getting it out that required multiple raps against the heel of my other hand. Once I did so I saw that the bottom of the cell was gooked up. When I went to insert a standard alkaline AAA cell, I encountered resistance, which led me to examine the interior of the C01. I found the usual powdery deposits on the side walls of the light.

I know that NiMH cells are usually reliable, and not prone to doing this, so my question is - What happens when an NiMH cell is drained to withing an inch of its life? I hadn't noticed any falling off of output so hadn't bothered checking the state of the cell. I am going to see if I can use a buffing wheel with my Dremel to get the nasties out of the body, so we will see what happens after that.

Those little guys are absolute vampires it seems. I'd be scared to use nimh in them myself for the exact reason you encountered. Good luck on reviving it!

I had Radio Shack and RayoVac NiMH leak white stuff just sitting by themselves so it is possible.

I don't use my nimh batteries in co1 eo1 or my other battery vampires. Those flashlights can kill them. I'm using old school nicad which are tolerant of deep discharge and behave different when they get near dead. Nicad drop like a cliff when out of charge.

I would really like to rehab this light. I tried scraping some of the gunk off, but that was a no-go. Should I use an alkaline or an acidic solution to try to neutralize the deposits?

Nimh is alkaline so a mild acid like vinegar or lemon juice etc should suffice.
I would then wash with water and then wash with 90%+ alcohol to absorb the water and evaporate off.

If they drop down to let's say 0.30v they are ruined.

vBDKv said:

If they drop down to let's say 0.30v they are ruined.

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Not necessarily, but if they are dropped low or reversed in voltage chances are they will lose capacity and perhaps develop high internal resistance.

All batteries can leak under the wrong circumstances. I've had NiMH overheat and leak, NiCad white powder, alkaline crud, LiPo puffing (precursor to who knows what), NiZn leakage, and of course those Ray-O-Leak batteries that turned the contacts in our toys orange.