Samsung 18650 25R is this battery still safe ???

The image below is of a three year old Samsung 25R which I've been using in a Manker E14-II. Please note the areas which are identified with the fuscia arrows. To me they appear to be leakage. Many times I have run the E14 to the point where it is too hot to handle. Is that the most likely cause? My charger is a Nitecore digicharger D4, so I don't believe that I have ever overcharged the battery.

The yellow arrow indicates where the flat top is indented. This is due to the + battery termination inside the torch being a solid button. The E14-III was updated to use springs as terminations for both ends of the battery.

I had been hoping to switch to protected LG MJ1. However, they don't fit.

Are any of these issues a need for concern?


I can’t see leakage in you photo, but a heavily misused battery! How were you able to damage the wrapper that badly? It is not safe to use in this state, you could cause a short easily.

Those might be Arc marks from shorts —- It’s a wonder you haven’t completely made that battery vent or short out your charger —- Throw that battery away and then figure out how to fix your light from compressing the cell —It’s just going to ruin another cell

yes that thermal damage is very likely related to high temps.

Somehow it got too hot and caused the wrapper to shrink back which exposed the top of the cell case. Plus you can see arc spots where it has touched across something to short the cell.

That’s quite a lot of damage. I would recycle and buy another cell from a reputable retailer.

Does the manker not have thermal Stepdown? If you can configure thermal throttling then you’re less likely to wreck the new cell.

Also, the damage to the top is concerning, I doubt any protected cell will fit given you’ve crushed an unprotected cell…??!

Do a nor test to see if the battery is still up to specifications.
If it’s still good just put a fresh paper ring on top and rewrap the cell or repair with tape and / or superglue or something.

When he shorts out the + and - inside that light — He’ll figure out if he needs something new — hopefully it’s just a Cell or Flashlight —Not a Hand, House, Etc

Once you start getting corrosion around the top edges like that the battery is not long for this world. You need to be a lot more careful with the wrapper especially on the positive end. There are many “stickies” at the top of this forum section. They are there for a reason.

I will figure out where to recycle and replace it.

I've looked through my records to see where I bought it and believe it was shipped with the Manker E14-II as part of an eBay order from China. Below you will find top and bottom photos of the two batteries I use. The Samsung 25R in Green is from Jan 2019 and the Samsung 30Q Pink was bought in the UK in Nov 2020. I alternate the batteries a few times a week. They are used every night for walking a dog off lead. While the 25R was used daily for 23 months, since Nov 2020 it has been used equally as the 30Q.

I don't recall the 25R ever having a paper or insulating ring at the top like the 30Q. Also, from the bottom pictures, I think it was shrinkage from heat which caused the wrapper to retract. Also, there is only a very slight depression in the center cap of the 30Q. In a caliper the 30Q is actually longer 64.9mm vs 64.4mm for the 25R. The depressed cap must primarily be due to expansion when overheating. Given the difference in the condition of the two batteries with similar usage patterns, I'm starting to suspect the Samsung 25R may in fact be counterfeit. In any event, I'll replace.

I've been casually visiting these forums since 2019. Thanks for the feedback and advice.

Some rappers end up being or getting more brittle than others. It could be the way you’re putting it in or out of your charger also. You need to pull back on the spring a little bit so the wrapper doesn’t get ripped or torn going in or out. It did not shrink from heat inside the flashlight.

REcycle it!!!

Where did you get those date stickers?

use a label maker to make your own custom tags

@lampliter, as @kennybobby surmised, I always label my rechargeable batteries using a Brother P-touch label maker. Comes in handy for keeping track of which are my oldest when AA/AAA are floating around with various family member devices.

Again, test the cell to see if it’s still good.
Cosmetic damage doesn’t mean the cell is toast.

+1… Agreed…. :+1:

Analysis of common leakage and rust of 18650 batteries - Battery Pack Assembly Line Machines Once you start seeing leakage, corrosion or other substances such as rust, the white crystalized stuff he is seeing it’s over. Edit. I’m specifically talking about signs of this stuff near the top outside of or under that small little plastic isolator that he still has on the battery. There will be very few cycles left on this battery and it will start self discharging or worse.