I have an Interstate deep cycle marine/rv battery to power the trolling motor on my canoe. It's about 2-3 years old. I loaned it to a friend to power a car power inverter to run his fish tank when his electricity was turned off, and while transporting it in the back of his car it tipped over and spilled at least a 1/3rd of the acid, maybe more.

Is this battery still usable? Could I buy more battery acid and refill it if it's 1/3rd to 1/2 gone?