No. The windings would melt long before then.Glyn wrote: ↑Dec 20, 2017 2:56 pmI don't think I understand what you're saying here sorry Buk.
Using the motors I've purchased as an example, they're rated at 48v, 20a continuous, 45a peak.
Are you saying that if I connected them to a 48v controller capable of supplying 100,000a, then they would indeed draw 100,000a?
My point was that a motor is not inherently "48V" by construction. For example, the "36V 201rpm" Q motors are widely rumored to be identical to the "48V 260rpm" versions.
A motor's speed is defined by its windings and magnetic constuction and is captured by its kV. The 36V 201rpm is 201/36 = 5.583 kV (rpm/volt). Feed it 48V, and 48 * 5.583 = 268. Close enough to the 260rpm rating, with the discrepancy explained by the fact that the windings, cores, & back iron have limits to how much magnetic field they can produce or contain -- saturation.
Feed that same motor 24V and you have a 134rpm motor, though it may well empirically measure as closer to 150rpm because nothing is close to saturation. Provided that the controller can deliver enough amps; and the windings (and intermediate cables) can withstand those amps.
Conversely, feed it 72 volts, you probably won't get a 401rpm motor because of saturation.
But, and this is really important for your application, you cannot simply take a motor that is rated as 48V and feed ever lower voltage at higher amperage in order to to achieve greater torque at lower speed. If your motors are designed to run at 48V 20A, and you attempt to feed them 12V at 80A, you will likely melt the windings or cables before you get the motor to a speed where it can use the amps supplied to do work; so much of the power you supply will be converted to heat which it is not designed to handle.
The benefits of a geared motors for low speed applications are:
a) the speed is mechanically divided by the gear ratio, so the motor can turn faster and get closer to its optimum efficiency band whilst the wheels turn slowly.
b) The torque produced by the motor is multiplied by the gear ratio, allowing more efficient delivery of the torque required at the wheel. At the expense -- or actually benefit in your case -- of lower speed.