Explosion risk with rechargeable NIMH AAA batteries?

[Vapor Vinny]

I've made a couple of mods. One using 4AAA rechargeable nimh batteries and one using 3AAA. Small vent holes in the battery compartment.

One is the risk of serious explosion vs. Lithium ION batts. I've used AAA batteries my whole life and only once experienced an bursting battery and that was with a Playstation 3 controller. It was a good pop, but it didn't do any damage to me or the controller.

What is the explosion risk with AAA batteries?

 

[Factor52]

I've wondered the same thing.. The best I can tell is there is some risk. The less incidents reported to the FDA the better. The enemies and vested interests have a tendency to grab on to one incident and not put it into the proper perspective. Hence I do believe that making it as safe as possible for everyone is prudent.

 

[Vapor Vinny]

One thing is certain, there are for more reported explosions with cell phones. And the health risks of cell phones are much more proven.

 

[LucentShadow]

I've heard of some quite explosive incidents with RC hobby battery packs (NiMH) during fast charging recently. I've seen some pretty questionable practices when it comes to those, though.

I've charged my AAA NiMH batteries on a fairly safe 15-min (4C) charger many times. They do get hot, and it seems to shorten the overall life of the battery. Charging them on a 1-hour (1C) charger would be more prudent. The charger should monitor each battery separately, to be fairly safe.

They should be able to handle normal vaping current draw. Short-circuits are hard on them, but I've done that momentarily with no serious effects. I suppose that adding around a 3-4 amp fuse would add some safety there.

Any battery can fail, causing varying degrees of damage, so treating them with caution is always a good idea.

From the research that I did some time ago, they usually don't fail in terribly energetic ways, but they can occasionally cause small explosions in extreme cases, because they can release hydrogen when they vent. Most consider them fairly safe as compared to li-ions, as long as good practices are used.

 

[Txrider]

Nimh are not prone to a runaway overheat in the way lithium batteries are I do not believe. The issue for a Nimh is when you try to charge it too fast, but were talking over 10 amps of charge. They can overheat and pop, the quick chargers use a thermistor or some such to monitor the temperature of the battery and drop the amperage to avoid overheating.

I don't think there is any type of battery that won't heat up and cause problems, and any battery in a metal shell that can hold pressure will pop if you throw too much current through it.