Unfortunately going directly into a differential probably isn't going to work for you. It would be like driving around in fourth gear (note: most EVers never use fourth).
It can work OK in a lightweight car with a big motor, but in something as heavy as a Caravan with all of the ICE parts PLUS the EV parts? Assuming enough batteries for a range of 15-20 miles, that's probably close to 5,000 lbs total weight. FWIW at 45mph, with that ratio, the motor would only be spinning at about 2800 rpm. This motor is happier (more efficient, less heat) when it's spinning at 4000-5000 rpm. For something this heavy you really need either: a big AC motor with a high reduction ratio, a multispeed transmission, or a couple big DC motors connected to your differential (and a REALLY powerful controller or two). Perhaps some kind of transaxle in the back? Or even tucking a second small tranny up with the 9" motor? >Hi All, >First off I'm a newbie so be gentle! >Reading the archives, great stuff! I have gotten info from some of >you on other lists or directly but I think I finally have made a >decision. Originally I wanted to use the Seimens drive that Victor is >selling but costs of a complete conversion and the range thing are >stumbling blocks for me. Here is what I need to figure out now. >What would be a good final drive ratio for city driving up to 80 KPH? >(about 45 MPH)I know most conversions work well in 2nd gear around >town. I would like to drive the rear wheels through a differential >with say a 4.11/1 ratio. is that too high or not high enough? I'm >thinking about replacing the rear dead axle of our Dodge Caravan with >something like a 9" ford with the apropriate gears inside. Drive this >with say 9" ADC motor via a small drive shaft and voila, Hybrid mini >van! I have details to work on like a clutch to disengage the drive >shaft so no extra load on ICE while on highway runs, but I really >think this is doable. Any thoughts on the ratio is what I really need >but comments about the idea are greatly accepted.
