Your motor rating is only 3kW (4HP) assuming 100% efficiency. This seems far too small for a lawn tractor.
For a comparison you could look at the old GE "Elek-Trak" models -- the most popular model 12 was 1.5HP for the drive motor. They carried six batteries and ran at 36V.
The motors are replacing a 13hp ice motor (maybe the right term is ride-on lawnmower rather than tractor). So about 4 hp for drive, which I think is more than enough, and about 4 hp for the blades which might be too little, but if it works I’ll probably be happy to cut the grass before it gets to long. With this setup, I can also eliminate some pulleys and the clutch, which hopefully will reduce the power requirements a bit. I’m going to use four 85ah marine batteries, and I’m hoping to get a couple of hours juice for just driving, and maybe 40 minutes of grass cutting.
That sounds about right to me.
The Arduino will try do reduce power to 130 amps per motor, and will allow 150-200 amps for max 5 seconds, and will shut of power completely if consumption is more than 200 amps for one of the motors.
You should still use a breaker
or fuse for overcurrent protection.