[ConnorJ]

Hi all,

I've been interested in electric conversions for some time and have been wondering, would it be possible to fit an electric motor (potentially with some down gearing) straight to the old gearbox and transmission, and program the ESC to make the electric motor idle at around 800 RPM so it behaves as a manual car where you can shift gears.

My thinking being that it would allow a smaller motor to make more torque, and means you could run it at lower RPM when cruising to increase range without the need for so many heavy batteries.

Or is this impossible... I would love to know if anyone has tried this sort of thing.

Thanks

 

[Ken S]

A common design for EV conversions is to use an adapter plate and shaft coupler to mate the electric motor to the transmission. You can buy kits for this approach. To drive, pick a gear and stay in it.
Simplicity is good. Complexity degrades reliability. Most modern production EVs use a fixed gear ratio.

Anyway... Take some time to read the forums (and the FAQs ) . There is a wealth of information here.

 

[remy_martian]

Running at low RPM at cruise does nothing to increase range...it could even shorten it. Yes, you can trade speed for torque, but you cannot conjure horsepower from a "small motor" which is what governs the top speed of the vehicle.

800 RPM is unneccesary. You can shift the transmission with a zero idle speed and run from a dead stop at zero RPM without slipping a clutch.

Batteries determine range. Weight is range. You need what you need.

 

[Zieg]

Motors make full torque from 0 rpm so as mentioned you don't need a clutch to get it going. There are options in some motor controllers to 'idle' at a certain rpm, but those are intended for use in an automatic transmission where the motor needs to run the hydraulic pump.

 

[brian_]

Having a choice of gearing ratios can help performance, and even efficiency, if the driver knows what motor speed to use. An average driver will make the wrong choice most of the time. In production EVs the normal choice is to simply use a fixed-ratio transmission and to use a larger motor that provides sufficient performance throughout the speed range despite operating the motor at something other than it's optimal speed essentially all of the time.

Many DIY EV conversions use the car's original manual transmission, mostly to make installation easier and to provide one suitable ratio of reduction, rather than to enable routine shifting. They often include a clutch, only to facilitate shifting rather than for starting off from a standstill.

 

[remy_martian]

They often include a clutch to serve as a coupling to the input shaft of the transmission.

The clutch is not necessary for shifting, but if it's there...