Exploding LiIon cells in watertight flashlights

[jlomein]

I have read a little about exploding liIon cells. One was a CPF article about a guy who had liIon cells in a flashlight, stored in a plastic container, kept in a wood cabinet. The cells exploded with such force that it blew out of the plastic container and but a crack in the cabinet door.

The other was a CPF experiment, intentionally trying to explode liIon cells in a Pelican M6 to learn more.

The consistent evidence that seems to present itself is that it is the watertight feature of flashlights that causes gases to build up inside when liIon cells fail. This build up of gases increases in pressure with time and causes an explosion when the pressure exceeds the flaslight's seal.

My question is this: If a flashlight tube is not watertight, instead vented to allow airflow, does it significantly reduce the danger of liIon cell explosion?

 

[SilverFox]

Hello Jlomein,

I am sorry, but you have reached the wrong conclusion...

Mismatched cells won't drain evenly. At the end of the discharge, the stronger cell will try to reverse charge the weak cell. When you reverse charge a lithium cell, it explodes. It doesn't matter if the light is water tight or not.

Tom

 

[Timson]

As Silverfox states...When a Li-Ion cell encounters a reverse charge or goes into thermal runaway through overcharge/overdischarge they will explode or vent with flames very spectacularly....Enclosed or not, it's gonna make little difference.

Other cell chemistries that are more stable can suffer similar problems but with less explosive tendancies.
All cells can vent gas and in a completely sealed environment - like a dive light the pressure can build to a point where the flashlight body can rupture.

This happened to a plastic bodied dive light of mine (can't remember the make) but it had 4 ALKALINE AA cells (Duracells) that failed.
The body blew apart and the head/reflector were all damaged.

I sent everything away to Duracell for refund/replacement.
They sent it all back saying that they couldn't attribute the failure to the cells and would not be offering me replacements !!!!

Shamefull cop-out.... Hence I'll never buy Duracells again - out of principle :scowl: ....Anyway I digress.

In a non sealed light the pressure would have likely vented out without blowing the body apart...but still would likely damage the inside of the light with all the corrosive gasses and liquids that come out.


Tim.