Ebay China 18650 Zero volts suddenly (from 3.7V). Expected?

I realize China usually means questionable quality but I figured I’d still ask. It looks like every other 18650 I’ve seen. The pair seemed to last ok in a flashlight (direct driven XML). But all the sudden one went from 3.7V to reading zero.

What could have happened? I’m new to Li Ion.

The protection circuit tripped you should be able to reset the cell by putting it in a charger depending on the charger. Why it tripped is another story maybe current overload.

This is what happens when you surpass the under voltage or over current protection threshold on a protected cell.

You just need to charge it. And considering it’s a dangerous ebay cell I would do that as far away from my house as possible.

You really should read up on li-ion cells and cell safety. Of course it looks like every other 18650 because it is 18x65 and round. But it is not the same at all on the inside. I urge you to get some quality cells panasonic lg samsung sanyo sony. You are playing with bombs.

Not to mention the cells you have are probably a true 800mah when a good cell will be up to 3500mah in addition to delivering more current.

Yes read the third link in my SIG please :wink:

You don’t even have a clue how misguided you are.
Did you know that Armytek, Thrunite, Klarus, Nitecore, JetBeam, Niteye, Olight, and many more brands are made in China!
Xiaomi, some of the best power banks for the price, superb mobile phones, action cameras, all their products have an excellent feedback…

You just need to avoid cheapest thing you find on aliexpress or ebay and you will find the quality easily :wink:

P.S. what is the brand of the cell that you had “problem” with?

They are probably the garbage cells that come free with generic lights.
Likely stating something impossible like 5200mah on the side.
Most of the ebay generics are shipping with “GTL” cells which I believe
stands for “Garbage, Total Loss”. :smiling_imp:

777funk if this is the case, you will get probably 3x the runtime out of a good quality cell, your direct drive light will be brighter due to a better cells better current capacity, and you will have better piece of mind that it’s FAR less likely to blow up on you or burn your house down.

Yeah “brand” is stretching it. These were 89 cents each shipped. They say 5000mAh on the side and look like this:

Consider yourself lucky that all that happened is one dropped to zero.

Stick some electrical tape over the ends and drop them into a battery recycle bin. You might even be lucky and find an old drill or laptop pack you can pull down for some quality cells.

But be aware that cells obtained like this are not protected and require greater safety and monitoring.

That is a very good point. Great care also needs to be taken when removing the cells from the pack.

Given the not particularly high price of some quality cells, I find it difficult to see why people still skimp on quality (and risking their own safety) for the sake of a few $.

At least it didn’t go negative. :laughing:

I think it is unfortunate but most people grew up with batteries around and are used to alkaline or small rechargeable batteries.
Then there is the notion that higher numbers must be better.
So there you go
“Let me buy this 5000mAh battery it is only $1 , what a deal see this one cost $4 and only has 3400mAh , score! Lol here is one of only 2600mAh for $10, suckers, and that 2600 has 4,5 star rating where the 5000mAh has 5 stars.”

To be honest it takes more than just surface research for folks new to the tech to learn some fundamentals. It is not presented upfront. For example I don’t think I’ve actually read in any cell info for newbs about the fact that 5000mAh is impossible, that fake cells are more widely sold in many venues than legit ones, why a protected cell goes to zero, or other things like this that we would call basic. There is no intro to li-ion that shows a dissected comparison between a garbage cell and a good one. No picture of an 18650 can with a lipo pouch inside. Things that we come to learn and be aware of. These infos are much deeper than on the surface.

I have come to understand these things through extensive reading but nowhere did I find this info spelled out for starters. At most, new people hear “stay away from **fire cells” but no clear explanation as to why.

The Miller the link in your sig is very good and very important info, but much of the info is scattered through all the links and lacks conciseness, that most newbies probably don’t read it all, or understand what they’re reading.

On cursory glance, there is a picture of cells in barrels in a warehouse, and a pic of a burned cell in a charger, but if one wanted to know that cells can become bombs in a flashlight you would have to be aware of it and specifically search for that. To be aware that used cells get rewrapped and sold as some random brand name, many just don’t know. As I said this info is not clearly presented in a single location.

Maybe if I have time someday I will begin to compile some stuffs to be added to the safety thread.

I don’t think we should be jumping on the backs and belittling anyone that purchases inexpensive cells that are sold with dubious capacity ratings.

The average person knows nothing about LiIon cells and takes the marketing info that is given at face value. Why would they not? 99.9% of people have never done any research once or ever on alkaline batteries either.

We’re here to be helpful, not smug.

My very first 18650 LiIon flashlight, from the early days, when AA was still king, came with two 18650s and a charger. I hadn’t even heard of LiIon, but was lucky enough to have purchased my flashlight from a reputable dealer and the supplied cells were AW. I wouldn’t have ever known there were questionable cells on the market if I hadn’t found these forums to educate me.

We can only try and educate!

When I first started we did not have KeepPower, Orbtronics, etc. We had Trustfire and other China brands that we trusted. They were my main batteries for over 5 years with no issues at all.



Yeah beginners here aren’t even aware of HKJ and his website.
It’s a completely different website. Further proving my point.
People new to this don’t typically start out browsing lygte-info.dk
You truncated the rest of my post which tied my statements to info available on BLF.

I thought it was clear from my words that I am aware of those links, new people are not.

Maybe someone can add them to this thread Lithium Ion Safety 101 important read

Yes I had many of the original Trustfire Flames, back when they were trustworthy.
But now that the wrappers are easily available, they are faked far and wide.
Finding a legit Trustfire Flame 2400mAh these days is like playing the lottery.