Warning: Do not put 21700 cells in chargers not made for that cell! (pics in post #4)

RC,
Your charger may be OK. Or just the one bay is cooked.
Basically, as other have said, you got a short.
But the short only passed current through the positive contact a short distance. The current didn’t pass through the charger.
So the positive contact got mucho hot and perhaps melted something internally attached to it.
Perhaps not.
Open the charger up and take a look for cooked components. Bet you won’t find any other that right at the positive terminal.
Charger being off sure didn’t cause this.
And yeah, the manufacturers could have given us a couple of more mm of length.
But heck, they save $0.004 per charger, so it’s a plus for them.

I just got the Vapcell S4+, Like the ability to throw some amps at bigger batteries.
I have the old version that turns the display off too fast. Supposedly a new version fixes that.
All the Best,
Jeff

I am now looking at HKJ's review of the Nitecore SC4:

https://lygte-info.dk/review/Review%20Charger%20Nitecore%20SC4%20UK.html

Apparently some unprotected 21700 cells fit, but not the ones that I have.

So before inserting a 21700 cell in a charger, do some research and make sure that it'll fit.

RC,
Just checked a flat top 21700, that’s 70mm long in the Vapecell.
Fits with lots of room to spare.

Oh, sorry.

(My post wasn't a reply to yours.)

I ordered a Nitecore UM4.

They will accept really long cells (up to 79.8 mm).

Just be aware that the "Olight Universal Magnetic Charger" will not work on "all the batteries" all of the time.

It will not begin charging a "protected Li-ion Battery" after the battery's protection circuit has tripped from low voltage until the battery's low voltage protection circuit has been reset by some other means.

Some chargers do not have this issue and will begin charging which resets the battery's protection circuit.

Even if you didn’t scratch the covering while putting the cell into the charger it is very possible that the small metal bump just pushed its way though the wrap due to the spring pressure.
Ideally the charger would have a spring that is soft enough when fully stretched to not cause this, but usually they are very stiff to make better electrical contact.
Plus the fact that you’re using a 70mm long battery instead of 65mm long makes it even worse.

If you had a charger that didn’t have that second bump, or if you placed the cell such that the two bumps were on the positive terminal (instead of one on the terminal and one on the edge of the body) this would not happen.
Also I still think if you used a samsung or LG cell this wouldn’t happen, those wraps are much harder to break through than this cheaper brand.

there is no electrical reason it should not work, i just think you broke through some insulation and caused a short

wle

I thought it vented, but come to think of it based on the videos I have seen of a venting battery it is unlikely he could have grabbed the battery if it vented. They usually catch fire, and even in the demonstrations they caused it to vent from a distance. That is probably just a surface burn, and the battery and charger may very well be OK. I just assumed he was saying it vented, but that battery does not really look like a battery that vented. As I post this, I have a question. Where can I find wraps that are a little longer than regular 21700 battery wraps. I have some protected 21700 that the wraps are a little short for. I need some wraps that are maybe 3mm longer to re-wrap protected batteries. I use these in some cheaper lights that have no protection built in the light, and also on some lights with stacked cells. I tried using 2 wraps, but then the battery gets stuck in the tubes of the flashlight.

Yeh, I bought a lifetime supply of Folomov A1s (same dealy) when they were stoopit-cheap at like 7bux a pop.

Always carried one in my bag, but stopped when I started EDCing my MH20 with built-in charger, so it became redundant. Still should, in case I get a non-18650 that needs charging at work or wherever.

Plus, they act as a makeshift powerbank if needed, too.

How much are you getting the UM4 for?

Seems like Miboxer C4(v4) would be another good choice at a very reasonable price.

I have cells with the wrap being torn in exactly the same place in your pics.
It happens when you have alot of pressure pushing the cell towards the positive end of the charger and you push the cell down in the slot (bay). When you push the cell down the positive end of the charger tab catches the wrap first with all that spring pressure and tears it when with a little more push the cell falls all the way down into to the slot like normal. It happened quite a few times with my 18650 cells (30Q’s). I never had a short but I learned to push the cell as far as possible to the negative end of the charger before I started pushing the cell in, so the positive end cleared the positive tab of the charger and set all the way down before I turned it loose. That solved the problem of having torn wrappers.

Also be careful with certain lights with sharp edges tearing the wrap. The Q8 has sharp edges inside. RC you get the sparky award today.

Strange, my Samsung 21700 40T doesn't even fit in Nitecore SC4.

I charge it in Opus C3100

Sorry you had this bad experience RC. I only have one 21700, and haven’t tried it in all my chargers. As things are, my 26650s don’t like to fit in adjacent bays in my multi-bay charger (Nitecore i8). I don’t think you did anything “wrong” - I’m not sure I or most of us here would have known to be so careful with a cell. I know now, though, so your sacrifice is not in vain :stuck_out_tongue:

As the others have theorized here, the length of the 21700 was simply too long, just a little angle when the cell was ‘forced’ into position ‘horned’ the wrapper unto the positive bump and it tore it, creating the short.
I have a similar incident were my 30Q’s wrapper was stripped off because of the pressure (in my case too much spring tension) and a poorly-designed battery carrier in my Niwalker BK-FA02S:



Here is the thread some years back: Niwalker battery carrier warning

While it smoked and melted the wrapper, fortunately nothing electrically bad happened to my 30Q and here it is now, powering my BLF A6. I used transparent 18650 wrapper I got from FT years ago, and the white insulating ring is from salvaged cells from laptop junk battery packs.

This is one of those “learn from somebody else’s mistake” moments. :+1:

Careful with chargers for sure, but ALSO good to check the surface of whatever you are inserting the battery into.

That solder blob took some time to work through that battery and is a dangerous manufacturer error. Glad you light didn’t go thermal in your hand!

I mentioned to Niwalker the dangerous design fault and pointed them to the thread.
They sent me a “new” re-designed carrier but because the springs are very stiff and with that solder blob still there albeit a little farther away, virtually very little allowance for space available, look at what it does to the wrappers:

The Xtar PB2 charger is another candidate for tearing off wrappers on the positive side of 18650 batteries. Cells fit in so tightly that it’s probably only a matter of time until something serious happens.

I paid $21.71 (total price) on Banggood.

Just a suggestion of something that might prevent future damage. Roughen the solder there with sandpaper and then coat the solder with clear nail polish. You would only roughen the solder to provide better adhesion of the polish. Allow to dry completely and may even want to put a second coat of polish on it. Just a thought.