Comment by rkagerer

I hope it doesn't contain any water at all!

Dry Powder or CO2 is what you need for energized electrical equipment. And considering there's potential lithium involvement, you might want something more specialized (e.g. F-500 Encapsulator Agent). I agree anything more than a small-scale incident you're just getting the heck out of dodge. I'd have built something along the lines of a concrete bunker, with an automated suppression system to buy time.