Given that the batteries weigh a lot more than the motors, I would have thought that motor efficiency (which scales battery size) was much more important than motor weight.
My back-of-the-envelope is:
- Assuming 0.4 kWh/kg for batteries, and they have to run for 4 hours, then the total mass per kW is 10 kg (batteries) and 0.08 kg (motor).
- A 1% increase in motor efficiency could eliminate 0.1 kg of batteries, which would let you double the weight of the motor.
- (My analysis is invalid if you need much higher peak power than cruise power.)
I'm curious how you optimize the entire system for such trade-offs.
My back-of-the-envelope is:
- Assuming 0.4 kWh/kg for batteries, and they have to run for 4 hours, then the total mass per kW is 10 kg (batteries) and 0.08 kg (motor).
- A 1% increase in motor efficiency could eliminate 0.1 kg of batteries, which would let you double the weight of the motor.
- (My analysis is invalid if you need much higher peak power than cruise power.)
I'm curious how you optimize the entire system for such trade-offs.