what is the diference between 48 and 72 V engines and controlers?
The higher the voltage, the lower the current for the same power.
If you want to get 2000W out of the motor, then at 48V you get about 42Amps.
If you want to get 6000W then at 48 you would have to draw 125Amps,
but with the 72V source you get around 80Amps.
Generally speaking you get the best efficiency when the amperage is near the
voltage, but you also have some advantage in keeping the current lower.
(easier on the batteries, less weight in wiring, less expense in components.)
does engine power depend on overheeting , so it is 5kW continuos and 20kW for short bursts???
Heat is a byproduct of inefficiency. The power is literally Volts x Amps - heat loss.
If you are well tuned (voltage near current) you get maximum efficiency.
You get to control the voltage, and load indirectly controls the current. If you apply
a load that needs 1000W, you must supply a voltage to the controller such that the
voltage times the current is (about) 1000.
does the controler have regenerative braking or do I have to buy some kind of regen controler?
No, but there are some recommended third party controllers with regen. Yao can help you
pick one that is appropriate.
From what I have been reading, the regen is not very efficient (<17%) and you are limited by
what your battery can absorb, where dumping a large current into the battery will shorten its life.
For the e-bikes, regen is pretty much on or off, so it's not much use for me.
can I use HPC100B 72V controller on this motor: http://www.newKellycontroller.com/product_info.php?cPath=21_62&products_id=711 ?
Kelly actually makes and suggests a great controller for their hub motor.
Yes, they are expensive, but you have to consider just how many of them you want to build.
One really good one, or several that almost work and one that does.
