Never keep your batteries in a charger when traveling!

[Mooch]

Whether it's just to work or around the world, using a charger to store your batteries can lead to a fire or bursting of your battery if the wrap is damaged.

I feel this is what happened during a recent flight (photos from a CNN post). Two batteries, it appears, were being stored in an Efest SODA charger in a day pack during a flight. One of the batteries went into thermal runaway and caught fire. Luckily, everyone was ok.



What caused this?

It wasn't because they were AWT batteries.
It wasn't because the battery ignited on its own.
It wasn't from being charged at the wrong rate.
It wasn't from being used too hard.

Eagle-eyed vapers might notice that in the photos one of the two batteries is reversed. Could this be the cause?

No.
I tested this in a SODA charger at both charge rate settings and there were no problems.

But, like many chargers, if the wrap is damaged and the battery slips a bit out of position the positive contact of the charger can short-circuit the battery center positive contact to the negative outer ring at the top.



This can force the battery into thermal runaway leading to a fire or even violent bursting of the battery.

NEVER keep your batteries in the charger when traveling. Yes, it saves space. But it's not worth the risk, especially when all the jostling could take an otherwise ok wrap and damage it.

ALWAYS store your batteries in a case, sleeve, or even a box and not in the charger.
ALWAYS keep your battery wraps and the insulator ring at the top of the battery in perfect condition.

 

[DaveP]

I've always taken batteries off charge when I'm going out or headed to bed at night. Obviously, there's no mechanical disconnect in the chargers I own or I'd hear a mechanical relay energize and de-energize. So, it's obviously an SCR or other electronic disconnect from the charger's circuitry that acts as a safety when charging is complete. Barring circuit failure there's theoretical safety when a battery is in a charger after charging is complete.

Then, there's mechanical issues like the split wrap you described. There's nothing that protection circuitry can do to prevent a mechanical short. It's why I'm possibly over-conscious about lithium batteries and charger safety. Thanks for the battery wrap hazard tip, Mooch. I would guess that this kind of split wrap thing happens more than we realize and it's a good reason not to leave batteries in after charging.