While true for lithium fires, a venting lithium-ion battery is not a typical lithium fire.

According to the MSDS for lithium ion batteries, fires involving them can be extinguished with a typical ABC fire extinguisher.

Lithium batteries (not the rechargeable kind) are the ones that need a class D extinguisher.

Edit:

> CO extinguishers, halon or copious quantities of water or water-based foam can be used to cool down burning Li- ion cells and batteries. Do not use for this purpose sand, dry powder or soda ash, graphite powder or fire blankets.

> Extinguishing media Use water or CO2 on burning Li-ion cells or batteries

http://www.uscg.mil/hq/cg4/cg432/docs/msds/MSDS_LiIon.pdf

Using water on an electric fire sounds like a dumb idea to me. But yeah, the MSDS does seem to say that...

A venting lithium ion battery isn't usually an electrical fire.

And what of all the molten wires that _were_ charging said battery?

Overcharging a battery isn't the only way to cause it to vent :)

Obviously there should be a physically separate circuit for cutting off power in the event of catastrophe. That's pretty much rule-of-thumb for large li-ion battery banks.

> Lithium fires do not require oxygen

I thought fire is by definition a combustion reaction, meaning some kind of material reacting with oxygen. What's fire, then? (I feel like a little kid, having to ask that...)

Generally, a fast exothermic reaction. Oxygen may be the most popular oxidant, but not the only one. Lots of stuff burns in pure chlorine gas, for instance.

Some substances bundle together their oxygen source (think of rocket fuel, or napalm), so they don't need to consume it from air.

It's possible for something to burn hot enough to split water molecules apart. I don't know if lithium metal qualifies, but that could be what the MSDS is referring to.