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36v ebike battery to 12v kayak motor Answered

Hi. I have bought an e bike with a 10ah 36v Li-ion battery pack. Can I use this to power my 12v kayak motor? I have the kayak set up with a pwm currently to control the speed. Do I need a converter to lower voltage. Or can I just use the pwm? Advice please.


Jack A Lopez

7 weeks ago

You have not told us anything about your existing PWM module.

Did your PWM come with the, what you call, "12v kayak motor?" What usually supplies input power to the PWM? Is it a 12 volt battery?

If that is true, do you suppose your existing PWM will be happy with having its input voltage increased by a factor of about 3 (from 12 to 36)?

The answer to that question depends on what the PWM is capable of.

By the way, in the event your PWM is happy with 36 volts DC input, the new range of duty cycle is going to be approximately 0 to 0.33, corresponding to time averaged output voltage of 0 to 12 volts DC = (36 volts)*(0 to 0.33).


8 weeks ago

If your boat motor is not too big, then there might be an alternative altogether....
I assume it uses a normal, brushed DC motor and not a fance BLDC....
A cheap motor speed controller like this could do the trick with some modifications.
All the do is to chop the input voltage to a PWM signal.
So on your 36V battery it would regulate from 0-36V.
On the potentiometer you can add a physical limit (like a notch) when 12V is reached.
Or you can add a second potentiometer is series that you use to limit the value of the controller.


8 weeks ago

Have to use a converter.


8 weeks ago

You will burnt out the controller, motor or both.
I don't know if a step down converter is feasable for these power levels but recommend sticking with 12V batteries for the boat.
In case you 12V system needs less than 10A you could still consider a step down converter but be aware about the heat produced and the lossses you have to expect.