I have calculated the resistances encountered by the vehicle. Now to find the required power i used formula

                    Required power= Total resistance force * Max. velocity

I came out with around 50 kw.....but this is the power required by vehicle.

How to calculated the motor power?

I don't think 50 kw powered motor is required to propel a vehicle with gross weight around 700 kg

  • $\begingroup$ Depends on how fast you want to propel the 700kg's. $\endgroup$ Commented Sep 15, 2017 at 19:28
  • $\begingroup$ Also recalculate for the power required to climb a moderately steep hill (say 10 or 12%) at enough speed to avoid getting in the way of traffic. $\endgroup$ Commented Dec 4, 2020 at 19:12

1 Answer 1


The vehicle power that you have found is the ideal power. It does not include any resistance forces that have not been taken into account. For example, air drag, heating (=friction) due to parts interacting, mechanical losses (things that bend / change shape during motion), etc.

To estimate the required motor power, the idea is to analyze the whole path from the motor shaft until where the main force occurs (tyre to ground traction). By combining (=multiply) the efficiency losses at each chain of force transfer, the general efficiency of the drive mechanism can be estimated.

The maximum power is needed when maximum force is required. Mainly the maximum speed for vehicles that aerodynamics dominate and maximum climb angle for vehicles like trucks.


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