I've had the battery for two years, it doesn't even get warm in use. I use a trickle charger to recharge the battery after I've been using it.
It says on the battery "valve regulated sealed lead acid battery"
I tested the current draw of the Bravo pump and it does draw about 20 amps but only when the piston pump kicks in at about 1psi.
Before that it's about 12 amps.
Before I got the Bravo pump I used it with my Rule pump.
The battery only costs £15 on ebay