jynxer
1 µW
I have a 20 inch rear hub that came from a recubnant Gonna be using it on a new bill. That I have, but the problem is I have no identifying markers or placard for the wattage or amperage can someone please help with identifying this hub?
Trying to find out what type of hub I have.
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Chalo
100 TW
That looks like an early Crystalyte motor to me, but I can't say for sure. And it doesn't really matter. It's an old design, so probably not super efficient by today's standards.
Motors often have a wattage rating, but that's only a rating. Motors don't have native wattages or voltages, and saturation currents are something most of us don't even approach.
If you have a battery and controller you can use to bench test the motor, you can figure out its RPM per volt. That will let you know how many volts you need to cruise at your desired speed-- aim for cruise to be about 75% of the free speed.
Your motor's ability to make power is limited by heat, so gross efficiency, physical size, and thermal mass all play a part. To the nearest approximation, any of these direct drive hubs should tolerate at least 100W per pound of hub, for some useful duration.
If it's a geared hub-- if it is, the axle will turn much more easily in one direction than the other-- then its reduced heat rejection ability will limit how much power it can tolerate versus an equally sized direct drive hub. And if it's a brushed motor (two thick wires going in, rather than three), it will have lower efficiency, thus more waste heat, thus less ability to use power without burning itself up.
Based on the apparent size of that motor, and assuming it's brushless direct drive, I'd guess that you can feed it 25 battery amps pretty much no matter the other specifics.
Motors often have a wattage rating, but that's only a rating. Motors don't have native wattages or voltages, and saturation currents are something most of us don't even approach.
If you have a battery and controller you can use to bench test the motor, you can figure out its RPM per volt. That will let you know how many volts you need to cruise at your desired speed-- aim for cruise to be about 75% of the free speed.
Your motor's ability to make power is limited by heat, so gross efficiency, physical size, and thermal mass all play a part. To the nearest approximation, any of these direct drive hubs should tolerate at least 100W per pound of hub, for some useful duration.
If it's a geared hub-- if it is, the axle will turn much more easily in one direction than the other-- then its reduced heat rejection ability will limit how much power it can tolerate versus an equally sized direct drive hub. And if it's a brushed motor (two thick wires going in, rather than three), it will have lower efficiency, thus more waste heat, thus less ability to use power without burning itself up.
Based on the apparent size of that motor, and assuming it's brushless direct drive, I'd guess that you can feed it 25 battery amps pretty much no matter the other specifics.
jynxer
1 µW
It is a direct drive I assume because I have pulled it apart and there were no gears inside
I'd perform the tests Chalo mentioned to determine the KV of the motor to determine what voltage you need to run at to get to the desired speed with a 20" wheel, and take a guess based on the phase wire conductor size on what current the motor might reasonably consume.
Chalo
100 TW
Vehicle Road Speed Calculator - 4QD - Electric Motor Control
This is a JavaScript page that helps you calculate the roadspeed of your vehicle.
www.4qd.co.uk
Bicycle Speed (Velocity) And Power Calculator.
(For correlating speed to the amount of output power you'll need.)
Online Metronome - A free tool to keep in time
(For determining RPM. I attach a single zip tie or flap of tape and let it slap something as the motor turns.)
