It says it can do 65C, which at that 4.4Ah capacity would mean 286a discharge ability. I don't know what sort of current is drawn from weapon firing stuff but it's way overkill, I'd say, for 2 speed 900s. That said I'm not sure what they can draw when running 24v.

Oh and that's a 7s, I'd say 6s would be better, as when fully charged it'll be a little over 24v, which is what the 85a Botbitz ESCs are rated at, and what many lower-end LiPo chargers peak at.

I'd think something like a 6s 4500mah 40C would do you fine.