Is it normal for a hub motor to act as a dyno?

gkspud

Finding my (electric) wheels
Dec 24, 2016
18
3
42
scotland
because it powers the lights when im going along with the battery disconnected, cant remember if the old controller did it as i didnt have the 48v lights,

does this mean i get free running of lights or at least reduced power use on battery when not under acceleration? 2x cree u5 motorbike lights :p

also wondering if its giving the batt a slow charge, have regen braking so feeds back into bms via schottky diode.
 
D

Deleted member 4366

Guest
All hub-motors work as generators, which is why they have a maximum speed. As soon as it starts turning, it generates in the opposite direction to the battery voltage. At low speed, the generated voltage is low, so there is plenty of voltage left in the forward direction to make the motor go, but at maximum RPM, say 20 mph, the voltage generated is the same as the battery, so they cancel each other and the motor can't go any faster.

If you have a non-freewheeling motor (DD), the motor generation can be used to charge anything when you're not giving power to it, but you get a braking effect in proportion to how much power you take from the motor.

You have to be careful when the battery isn't connected because the voltage isn't regulated, so your lights can go pop.
 

gkspud

Finding my (electric) wheels
Dec 24, 2016
18
3
42
scotland
is dd 1000w hub motor, has regen braking, willl try test next time on a hill if lights or the horn add drag as upgraded them to cree u5's and should be about 12w each, only prob with em is cars think i am motorbike:p
 

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