SLA battery charging


Joined May 19, 2014
Taking a motor and using it as a generator, you don't know what output will really be. So, if you are going to use it only as a generator, then get a generator. You will then know what to expect out of it as far as voltage and current. The generator specifications will tell you the amount power you will get per the RPMs.

Small generators will be more expensive than small motors. A second option is to get a DC motor and characterize it. You would need a voltmeter, a few load resistors (cheap) and a hand drill. Connect a load resistor to the motor and spin the shaft with the hand drill. Monitor the voltage across the load resistor while you crank up the drill to determine if it will output the voltage and current you need to charge a battery. It is not rocket science, just you learning about motors and generators.

Pick up a small cheap DC motor (<$5) and play around with it.
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Joined Feb 5, 2014
Just came across your original thread, and thought I'd point something out: I had need for something similar (not a bicycle, but a DC tug), and found a cheap board online that I think will do what you're pursuing, without multiple motors:
1- it will drive an DC electric motor using a variety of inputs such as PWM (ie- hobby RC controller & receiver), or variable voltage, or serial data
2- it is programmable as to drive motor response along the range of the input
3- it can be programmed to limit current into the drive motor, protecting it & the batteries in case of a stall
4- it can be setup to regenerate the batteries during coasting
5- it's relatively cheap
The company is Dimension Engineering, and the product is either the Sabertooth (dual motor) or SyRen (single)


Joined Jun 19, 2012
With all the inefficiencies of energy conversion you will encounter, I doubt you will obtain any useful recharge of the battery from your regenerative braking scheme.

Lot's of cost and complexity for dubious value?


Joined May 19, 2014
Golf carts have been using regenerative braking for well over a decade and have shown that it is worth while. The question is, would it be worth while on a bicycle?