What amp rating ESC do I need?

I am working on an electric longboard, retaining the original battery pack and brushless hub motors. I want to be able to control this with an Arduino. I want to know what size ESC I will need. The battery pack is 30V and the hub motors have a 1200W rating each. Will a 50Amp ESC be sufficient for each motor?

• That depends a lot on the conditions and qualifcations of usage and the ratings you give - a big problem is that those are marketing driven hobby product ratings, not engineering ratings, so unless you can find an actual data sheet (and be confident a given example will meet it) it is hard to give an engineering answer, vs. simply looking at what worked for other people. Dec 5 '16 at 5:10

This is why we have Ohm's Law: I = P/E

• P = Power (Watts)
• E = Electromotive Force (Volts)
• I = Current (Amps)

You can calculate any of the factors given two factors:

I made an Ohm's Law calculator online here: http://www.rcrowley.com/eirp.htm

If you plug in 30V and 1200W, it shows that the current is 40A. So your 50A ESC should be adequate.

• Feel free to reveal why you voted this down???? Dec 5 '16 at 5:50