Has anyone else experienced these strange looking stains underneath battery shrink wraps?
This has happened to me with several batteries of quality brands, such as Samsung 35E/30Q and VTC6.
All batteries work fine, i.e. voltage drop, temperature, internal resistance look fine and unsuspicious. I do not think it is any moisture as these stains do not disappear while the battery warms up. So, I suppose it’s grease from the flashlights‘ threads seeping through microscopic gaps underneath the shrink wrap.
What do you think? Is that anything unusual or did I just miss to read it anywhere posted before?
My wraps never look as good as yours, but my batteries don’t have these “stains”. I clean them, but they weren’t dirty to begin with.
I normally wrap 20-30 batteries each year.
Not that I have any stains under the wraps, but there are some residual chemicals from the manufacturing process that I’ve encountered.
As I smoke, after manipulating cells I would get a stingy and lip-numbing taste, transferred from my fingers. Not very good! But that I’m aware now I take the time to clean the cells with alcohol and after any touching, wash my hands.
Just hypothetical, but maybe these chemicals leak from the can? They would rather show up at the positive terminal.
And as you proposed, perhaps residual oils from thread lubrication.
Looks like it could be moisture/liquid of some kind. I typically double wrap my cells to add extra protection and eliminate rattle in lights, if you’re determined to do something about this that’s what I’d do. Doesn’t likely indicate any issues though.
It’s easy enough to rewrap. Just get some lighter colored wraps that you can write on in magic marker because once you’ve wrapped a bunch and they all have the same wrapper you forget what’s what. You just need a hair dryer. Not all aftermarket wraps are as thick and tough as the original ones.
What I with new cells these days is write the date received and then put a clear wrap with an extra positive insulator. For lights without a + spring, I’ll solder on a 1mm thick brass button.
A couple of my batteries have the same look. It happened after I used some isopropyl alcohol on a cotton swab to clean the terminals. The alcohol seeped between the wrap and the battery. Now I make sure l use less alcohol when I clean my batteries.
Thank you all for sharing your thoughts and suggestions so far!
This could be the root cause because that’s what I did to these affected batteries (too) often. I am a true cleaning maniac if it comes to grease or any residue left on the battery terminals. I frequently use cotton swabs and this stuff here to clean any contact surfaces.
I had that happen to the batteries in a Vape device. I had a long layover and went repeatedly back and forth from a cold air conditioned airport terminal to a very hot and humid smoking area. Condensation and heat I guess. I still have those batteries after 3 years and they’re ugly but work fine
