CVT and regenerative braking?

Question by Jon M: CVT and regenerative braking?
I’m working on plans for an electric motorcycle conversion. I’d like to do a Continuously Variable Transmission in order to maximize battery power and speed. The bike is shaft-driven, which makes it particularly difficult to change gear ratios in any direct drive manner, but also makes it good for a CVT.

However, I’m wondering what the effect of a CVT is on regenerative braking? More effective? Less effective? No effect?

Also, any ideas for locating/salvaging and appropriate CVT? The ones I’m familiar with are from 90’s Honda Civics, and I’m not sure it’s feasible to try to adapt.

Thanks!

Best answer:

Answer by Attorney
A CVT should not have much effect on regenerative braking .. I am not familiar with the control systems on a CVT but thinking about it.. a CVT with an appropriate control system it might actually help produce more electricity if you can control it so that the motor is turning rapidly when you brake in a regenerative braking mode.

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3 thoughts on “CVT and regenerative braking?

  1. This was how the Urba-Electric operated back in the 70’s. This was a car designed and built for the February 1977 issue of Mechanix Illustrated. At the time, it was an electric car capable of 60 mph with a 60 mile range that could be built for less than $ 1,500.

    They had three voltage levels that were selected by push buttons. Stepping on the accelerator switched on the electric motor to the voltage level selected and operated a stepper motor that adjusted the gear ratio of the CVT. The effect was that the electic motor operated at one speed determined by the three push buttons and the car speed was controlled by the accelerator pedal. Should the driver ease up on the accelerator, the momentum of the car would run the DC motor at a speed higher than that determined by the voltage level selection hence charging the batteries (regenerative braking which was a novel concept back then).

    The Electromatic belt driven CVT used by the Urba-Electric was one used with small industrial machines and is no longer availble but similar belt driven CVT’s still exist today. ATV’s often have CVT’s.

    There was a follow on project in 1977 called the Urba-Trike.

  2. You want the CVT to operate in reverse to the braking pressure you apply. E.g. if you lightly touch the brakes you want the CVT in a high gear so it only creates a small generating resistance. If you press hard, you want it to down shift so that you are generating more power and creating more resistance.

  3. There’s a CVT in the Prius, I think CVT will make regenerative braking easier to control, if not more effective. I’m not sure if there is an appropriate CVT for use on a motorcycle, every one I’ve heard of is in a car. Even small cars usually have much heavier transmissions than you’d find on a bike.

    For an electric bike, why do you need a transmission at all? Most electric motors can handle the torque and rpms of driving with no transmission, and very little difference in efficiency based on rpms. If your motor can handle that, why not save yourself 20-60 lbs? Less weight, less things to break, simpler regenerative braking.

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