750 watts or 500?
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gromike
Well-Known Member
- Region
- USA
- City
- City of Dreams
You have a 500 watt motor -- if you have a 500 watt motor controller. My 500 watt motor gets fed up to 1500 watts from my 30 amp 52 volt (nominal) controller.
The watts your motor consumes depends on the power fed to it by your motor controller.
The watts your motor consumes depends on the power fed to it by your motor controller.
Thank you. Cheers!
Chargeride
Well-Known Member
The motor rating is important, its the limit for continuous use at that power.
A bafang 750w hub is much meatier than the 350W version and can dissipate heat a lot better.
A bafang 750w hub is much meatier than the 350W version and can dissipate heat a lot better.
Thank you. Cheers!
Jeremy McCreary
Well-Known Member
- Region
- USA
- City
- Carlsbad, CA
My fairly typical 500W hub-drive has a 48V, 25A controller putting out 48 x 25 = 1,200W. Are you SURE your controller's only rated for 500W?
If so, not much point in having a motor with a nominal 750W that could peak well above 1000W.
If so, not much point in having a motor with a nominal 750W that could peak well above 1000W.
That's what it says on the controller. I think it's 750 peak watts…? Misleading marketing says 750 watts.
harryS
Well-Known Member
Your KT controller label says 18A peak, so that's around 900W peak at 50 volts. That part is real. If the battery is big enough, their controllers will deliver up to peak power,.
Hard for a fat tire trick to put that power to the ground though, and probably hard to make a turn at full speed too?
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Hard for a fat tire trick to put that power to the ground though, and probably hard to make a turn at full speed too?
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In BC the law says an ebike can have a motor with a maximum of 500 watts. If my controller says 500 watts, then I think I'm legal. I'm an old man. I don't drive hard or fast. Only use it for short rides and picking up groceries. Trike has loads of power for me. Cornering is a little weird but I take it slow. I don't think I've ever reached full speed. I really enjoy riding it though and look forward to having it fixed. Thanks to your help, it won't be too long.
PedalUma
Well-Known Member
- Region
- USA
- City
- Petaluma, CA
A highly respected member and expert @m@Robertson has a fleet of personal cargo bikes. He down tunes controllers feeding large, robust motors for durability. In effect, that's what you are running.
Thanks
spokewrench
Active Member
- Region
- USA
Also, a beefier motor may have fatter wire, which will produce less heat. I don't know what gauges are used in e-bike motors, but if a 350 had 18 gauge and a 750 had 14 gauge, equal current would produce only 40% as much heat in the bigger motor.
Back EMF, which reduces current, increases with motor speed. Current would be highest at the lowest rideable speed, struggling to climb at full throttle. Heat production varies with the square of current and inversely with resistance. The BPM R-750 seems to weigh 150 pounds and is rated for a 400-pound rider and it seems a 110-pound passenger. With a gross of 660 pounds (300 kg), a fairly ordinary grade could slow it to a crawl. For a trike, steering at walking speed or lower wouldn't be a problem, so the rider might continue at full throttle. That could explain a 500W controller to limit current with a 750W motor to reduce heating.
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