[Invictus3593]

As I work at a battery store, I can back up the notion of a marine deep cycle battery for running motors and the AC inverter, but if you're charging batteries off of the cart's power supply and doing all that, FRC batts aren't gonna do the job but I'm not certain a marine battery will. The marine battery will be good for a couple hours at a competition,
as its reserve capacity will only last for about an hour and a half -- two hours if you're lucky -- before you have to recharge. You would need to take serious power saving actions like turning it off when you aren't using it and keeping the motor controllers set at coast at all times before you could really get the most out of it.