Found a better selection of sprockets. They are at
Shoup Manufacturing Company I ordered #50 sprockets. I got a 9 tooth drive gear and a 32, 34, and 36 tooth driven gear. They are the weld on hub type so I also got an X series 7/8 hub for the axle and a V series 7/8 hub for the motor. The available gear ratios with those driven gears are 3.55:1, 3.77:1 and 4:1. That should pretty much cover any range I need keeping my 4000 RPM limit of the motor.
Now that that part looks like it is pretty well settled it is time to move on to the next part, the controller and batteries. I don't think the Mars brushless motor can take much more than 72V and still have a long life. So I am not really sure I would ever use more than that. I could always modify the controller to boost it's output if it ever comes up I suppose. So the 72V 300A w/regen controller looks like my best bet.
For the batteries it looks like it is ideal to charge them individually. That is not hard really if I just use 5 or 10 amp automatic chargers, it would just be a mess of wires and crap to hook up all the time. Another simpler option is to charge them with one 72V charger and balance them using a balancer of some sort
The Balancing Act | ELECTRIC-LEMON shows a pretty simple circuit to balance the batteries over time. That should get them charging and working as long as possible. The fun part is trying to figure out what kind of battery to use. I planned on using AGM-31 but I really don't think I can fit 6 of them in the car and still have room for anything else, they are pretty big batteries and heavy. I don't really think I need that much capacity anyway. I can get a
MK 8A24 79 Ah (20 Hr) AGM Sealed Battery - Batteries: Sealed Agm @ AltE 79AH battery that looks like a good size to cram in corners in the car. 6 of those would be a lot lighter at 50lbs each. I am not sure what kind of range it would give me though.
Anyone know of a better battery to use?