Black circles on 26650 battery negative ends?

LED Flashlights – General Info
1

Hi,

I only have a small number of 26650 batteries, 4 KKs, 1 TrustFire (flame), and 1 something else, but I’ve noticed that after I used them in several different lights, they all have some black “circles” on the negative end of them.

Is this “normal” with 26650s? I don’t see this kind of thing on any of my 18650s, even when I use them in the same lights (with adapters).

Anyone else seeing something like this? Is it “bad”, or is it “normal”?

Thanks,
Jim

2

It’s caused by those brass sleeves that cover the spring. Lately I’ve been removing them. If the spring is too strong, and/or the batteries tight fitting, they can cause denting or depressions on the end of the cell. Removing the brass cap will also help reduce resistance.

3

Ouchy,

Thanks for that. I was kind of worried that it might be indicative of “burning” :).

I’d remove the covers, but the springs seem like long and “skinny” and would be worried that the springs without the covers would just bend over?