l am all in on this. I have also wanted to do this. I am in the battery market sector (Li-Ion) and I think this is a fantastic application particularly rock crawler for the reason Skiz Riz pointed out of 100% torque at any rpm. You will not need near as much battery as a Volt/Leaf/Tesla as you really don't need the range or speed of these vehicles. I am curious of your choice of motor and number. It may may make sense to go with hub motors at each wheel but I have not found any that were durable / cost efficient. I think it definitely makes sense to go Li-Ion as I think you could go with about 12 kWh and probably keep the weight under 1,000 Lbs.