Some people put the cells in first and would then connect the charger. In fact, in the RC hobby many people do it this way. hobby chargers can be finicky at times…
I would rather be elsewhere when switching on the charger rather than put the cell in when already powered on… I mean… normally nothing happens… but what if?! I like my face the way it is.
Like I said I’m no expert but I’m pretty sure the chip in your charger is not powered by putting your batteries in to charge so how can it work? It’s not like a flashlight where the chip is powered by the battery. So I’m assuming here but you basically put in a very powerful battery in and completed the circuit with no control and it dumped all that power with no regulation and nowhere to go, unlike when it’s plugged in.
With sprung bay chargers like the one used, if there is no clearance of the cell positive and the charger positive when inserting the cell then there is a risk of damaging the wrap when inserting.
You should use the cell to push the sprung charger contact down, lay the cell flat in it’s bay then it should slide up to make contact.
Don’t push them directly in flat as you will catch the cell wrapper on the charger contact and wear or a direct rip may occur in time.
Cell wrappers are very thin plastic and easily damaged especially on corners when pressing over other hard objects like metal with protrusions.
If you do need to cram one of the larger cells into a charger then use a thin sheet of tough plastic etc to hold in the bay over the charger positive contact while inserting the cell to prevent wrapper damage. Once the cell is flat in the bay pull the plastic sheet out while holding the cell flat.
Also check your cells wrap from time to time to make sure it is intact, chargers with dimple protrusions on the contacts like the one pictured are better at poking through any holes and welding, I prefer contacts that are flat.
I use several Molicel INR-21700-P42A. I have found their wrappers to be brittle and easier to damage than the others. Great cell, weak wrapper.
rewrap the cell and move on.
that charger is too tight for a 21700.
it tore the wrapper with the 2 contacts due to the pressure of forcing it in.
at least you got it out.
super high drain cells like the p42 get pissed off very quickly when shorted.
Some wraps are tougher than others. Clearly it tore. Check battery voltage. Likely still good, just need to rewrap it. Edit, as others have said.
Yep. I’ve had several cells where the wrap cracked and peeled back near the positive end.
Remember plastic is made with plasticizers — chemicals used to keep it soft and flexible.
Cheap plastic uses less of the material or cheaper material.
Those evaporate eventually (they’re what makes that “new car smell” and oily film on the inside of new car windows)
Once they’re gone the plastic isn’t plastic any longer — leaving a brittle fragile material behind
Based off of the pictures you posted it clearly seen that you damaged the wrap, lightly which caused short and that damaged the wrap a little bit more
So… charger was no problem, except battery bay wasn’t long enough
No electrical issues
Because the PCB added to the 21700 is between 3 and 5mm, so that adds to the length of the 21700, and the idiots who designed the charger did not decide to add a few extra mm travel on the charger bays. I have the same charger, but fortunately the Hohm Tech School charger that cost me less than 10 bucks fits. Stupidest thing ever that my expensive Xtar, Nitecore, and Efest chargers will not allow a 21700 protected battery, but that cheap 10 buck charger works fine. It does not have the capability to measure battery capacity or internal resistance though. Why the charger manufacturers did not add an extra 10mm length to the bays is hard to understand.
I would love to see chargers with 90mm slots so my fat fingers can easily put them in and take them out. All of my battery wrapper damage happens when trying to put them into and out of chargers.
If the charger was not plugged in, it is nothing but pieces of metal. The only possible cause had to be either a torn wrap, or the pressure put on the positive post bent the positive contact and spread it enough to short under the wrap. If you look at the positive post on a battery, it is shaped like a tripod. If enough pressure is applied to the top, it can further spread the tripod shaped supports. That is perhaps even more likely than a torn wrap. In any case, it was a dead short between the positive and the outside of the battery that is negative. Lucky it did not catch fire, as they often do. Some chargers that can accept the batteries will not even list them as working because the charger was made before 21700 batteries came out. If it does not fit with a few mm to spare, do not force them enough to exert much pressure on the positive post.
You can always get one of the olight universal magnetic chargers. It consists of two magnets that you put on the positive and negative and it auto detects polarity. That will work on all the batteries except the ones with a positive and negative post on the same side like is in a bunch of olight flashlights. Go figure, they designed a charger that will work with every battery except theirs.
That is a Molicel p42a battery, and is one of the best, if not the best 21700 batteries on the market. In Mooch’s battery tests it even outperforms the samsung 40t and 30t. He can’t buy a higher quality battery than the Molicel p42a because they do not make a higher rated 21700 battery.
It seems clear that what happened was that the cell fit so tight it pinched through the plastic wrap and shorted out the cell. The charger will be fine, the cell should be gotten rid of. When you insert a cell into these style chargers, always insert the negative end first, draw back the spring, and lay the cell down, still holding back the spring yourself.
Actually some chargers like my Xtar Dragon VP4 plus can be loaded with fully charged batteries and serve as a power bank to charge cell phones and ipads and such. In any case, no charger will just drain a battery quickly when unplugged, it needs a load. If a charger not being plugged in could do that it would be too dangerous to sell. Power failures do happen as can accidental unplugging. Having looked closer, both the positive and negative are burnt between the positive post legs, so this was due to a torn wrap.
I have DLYFull T5 charger and it's very tight with 21700 and slightly better with protected 18650s.
I was always worried about wrap damage at the front in case something like this happens.
So I fixed the problem with stick on shim insulators at the front of the battery on the top of a wrap. Even if the shim gets torn (it hasn't so far) it would be much easier to see the damage than without it.
I have been afraid to jam in 21700 into the T5 otherwise like it well.
I will continue to be careful with inserting cells after reading this thread.
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.