There isn't a need. In my ultra 4 race car I'm only designed for 1 battery, but will have a better alternator. That's designed in case it's rolled over I can get it back over without it being dead.
Yes but your ultra 4 race car doesn't have anywhere near the same amount of accesories as my jeep..
It runs 2 radiator fans, oil cooler fan, trans cooler fan, fuel pumps that have to pump up to an equivalent of 900 hp, communications, future gps, engine, lights when necessary, and a lot of winching when necessary. It runs a descent amount.
I think you would be better served with an AMG battery.