New road ebike Project.

[fenomeno]

Hello
I'm looking for good material for my new project. Find attached this motor test values. It is a thru axle one.
What increase in torque/reduce in amps will I expect if I switch to a 48v battery?



Thanks for answering
Regards.

 

[Raboa]

Hi, what motor are you using? Thanks

 

[saneagle]

Hello
I'm looking for good material for my new project. Find attached this motor test values. It is a thru axle one.
What increase in torque/reduce in amps will I expect if I switch to a 48v battery?

View attachment 61142

Thanks for answering
Regards.

You can forget all that. What matters is that you choose a motor that has a maximum rpm of about 1.3 times your expected modal rpm to get maximum efficiency. That one might have a max efficiency at 218 rpm. It's not clear whether the 218 is max or modal. Efficiency seems to be too low for max. When you go up to 48v, everything shifts up by 1.3, so if 218 rpm would be it's max efficiency speed, it'll make max efficiency at 283 rpm, which is about 23 mph in a 700c wheel. It'll have enough torque at 48v for a road bike. If you're going to stick with legal requirements, it might be better to run at 36v, then increase current to 20A to get more torque if you need it.

 

[fenomeno]

Hi, what motor are you using? Thanks

I'm between these two:
TruckRun RN04KL and Bofeili Bofeili 250W. Both are Thru axle hub motors.
Thanks.

 

[fenomeno]

You can forget all that. What matters is that you choose a motor that has a maximum rpm of about 1.3 times your expected modal rpm to get maximum efficiency. That one might have a max efficiency at 218 rpm. It's not clear whether the 218 is max or modal. Efficiency seems to be too low for max. When you go up to 48v, everything shifts up by 1.3, so if 218 rpm would be it's max efficiency speed, it'll make max efficiency at 283 rpm, which is about 23 mph in a 700c wheel. It'll have enough torque at 48v for a road bike. If you're going to stick with legal requirements, it might be better to run at 36v, then increase current to 20A to get more torque if you need it.

Thanks a lot for sharing your knowledge with me.
I think that this one complies with your statement ( "choose a motor that has a maximum rpm of about 1.3 times your expected modal rpm to get maximum efficiency")


Max efficiency 356,4 rpm
356,4/1.3 = 274 rpm (expected modal rpm)
274 rpm = 35,3 km/h for a 700c Road wheel with 30 mm road tyre (Wheel perimeter)

32/33 km/h for 150w of mechanical power... it's ok I think, don't you think the same?

Thanks.

 

[saneagle]

Thanks a lot for sharing your knowledge with me.
I think that this one complies with your statement ( "choose a motor that has a maximum rpm of about 1.3 times your expected modal rpm to get maximum efficiency")
View attachment 61151

Max efficiency 356,4 rpm
356,4/1.3 = 274 rpm (expected modal rpm)
274 rpm = 35,3 km/h for a 700c Road wheel with 30 mm road tyre (Wheel perimeter)

32/33 km/h for 150w of mechanical power... it's ok I think, don't you think the same?

Thanks.

Whether it suits you depends on whether you want legal or not. It's too fast for legal, even at 36v. It's too fast for 48v, whichever speed you want to go. Another consideration is your weight, which you haven't told us.

 

[fenomeno]

78 kilos + 15 bike + rest = 100 kilos overall.