Originally Posted by bbrinkley
My main concerns is how you guys think the direct drive would work as I like the ease of a simple forward/reverse.
To go direct drive you need a really lightweight vehicle and a lot of torque. I think if you used lithium batteries you would obtain a driveable vehicle with a usable 40 mile range. But it wont be fast and probably not a lot of fun. I doubt this would be the case if you use Lead Acid.
Assuming a 40 mile range and 350wh/mile you need a minimum pack size of 14kwh. Since you want a Curtis setup you can go at most 130 volts which means 36 lithium cells. To get 14kwh you need 122AH cells. Since you dont want to ruin your cells you will want to do at most an 80% DOD so this increases to 152AH. The next largest cell above this is 160AH from Winston and Hi Power but I dont know how easy those are to get. Beyond that are CALB and Sinopoly at 180AH. 160AH * 36 cells = 18.4kwh and 180AH * 36 cells = 20.7kwh. The 160AH pack should give around 53 miles range and the 180AH pack should give around 59 miles drop dead.
A pack of 160AH cells would weigh something over 394 lbs (179kg) and 180AH would weigh 444 lbs (202kg). This is probably going to increase the weight of the vehicle slightly over stock. Certainly less than 100 lbs once you remove all the ICE stuff.
You are looking at a lot more weight in Lead Acid. I think about 5 times as much at least to get similar range when the LA batts are new. I will let someone else do the LA calculations. I dont think you would be happy at all with the acceleration if you are carrying around 2000lbs of lead on direct drive.
I think it is barely practical to do an AC50/Curtis setup sans transmission on Lithium. I don't think it is practical at all if you use Lead Acid batteries. I suspect you will have an EV grimace if you attempt this.