[sebazzz]

Isn't water the wrong solution then? In the fire triangle of fuel-temperature-oxidizer, you can also take away the oxidizer using foam, can't you?

[Turing_Machine]

Yes. Water is also a very poor choice for gasoline fires.

At least the battery will mostly stay in one place, rather than floating off on the surface of the water, possibly setting things on fire at a considerable distance from the original source.