Fire...what could cause this?

Cross posting from another (non flashlight) forum; the supplier mentioned is one that I’ve heard recommended on here as a UK based seller of genuine cells. I’ve used him several times myself, so I’m trying to find out what could have caused the following?


short associated with the protection board.
pic not very good.

Bad juju!

It looks like a short circuit occurred in the protection circuit, but it would need to be dissected to determine for sure.

The cell itself appears intact and did not burst or blow fire out the ends, so overcharging doesn’t seem likely.

left cell is shoddy assembly of the protection.
right is cosmetic damage from the flameout of its neighbor.
i would rip the protection off of all of these you have.
the cells are fine.
i always thought that adding a protection board actually increased the odds of a dangerous failure.
this is what i was thinking about.
thread should be moved to rechargeable batteries and possibly to a subforum like smoke,fire,and hot cells.

I don’t think Panasonic adds protection circuits themselves to any cells. So the protection board and assembly might very well originate from any shoddy backstreet shop in China. Quality thereafter.

Burning cells can be really dangerous, so make sure to buy Li-Ion cells ONLY from reputable sellers (that knows where to get quality cells/parts/builds for resale).

It looks like there was a short between the positive wire and the negative body of the battery, at the bottom. Maybe something moved a bit when the battery was removed from the charger.
This battery is long and there could be excessive pressure with the charger tab, particulary when removing the battery while you have to push on the tab even more.

This is why the only protected cells I use are Fenix. I don’t know any other manufacturer wrapping protected circuitry links in a steel jacket.

Very interesting seeing a theoretical risk of protected cells becoming reality!

It is likely the internal overcurrent protection in the cell tripped

Usually those Panasonic cells have on both sides of the metal band Kapton tape
There must be a sort of mechanical penetration of the insulation