I always want to say, your attention to detail and quality is commendable. The little things that most observers wouldn't even see. You are definitely a Fabricator and Craftsman.
I am still not sure of capacity because I have not tested the batteries that hard. I might have been able to get away with 6 for what I do. * It certainly would have been a lot lighter*
There is a large relay to turn the motor on and a reversing relay setup which uses 2 relays for reversing.
Input to the controller has a couple options for the potentiometer/gas pedal. Ironically I have a 10k pot put in the gas pedal but the gas pedal travel only moves it a fraction of that and I was able to select the potentiometer in the controller for the range I have. If anyone has more questions on this I would be happy to help.
This is basically the document I used to hook everything up:
I will send photos as I use it. I just got it done so it will be as things come up. I have a laser metal cutting shop with my neighbor next door and I run back and forth with a lot of stuff from time to time. Literally across a field from the shop to my place. I am always hauling welders/tanks and projects back and forth. With the old Cushman it has helped me service the tractor from time to time. On one occasion I cut a valve stem on the large tractor tire on a Ford 8N. I ran jacks and tools out to the tractor, pulled the tire off and was able to lay it flat across the bed by myself, take it back to the shop, got a new valve stem put in, aired back up and was going again an hour latter.
These and yard work are my typical missions. Last week I just hauled a scrap small block Chevy engine over to the scrap bin with it.
Here are a couple photos of using the Cushman before building this vehicle: