I have obtained data of the efficiencies of a few models of electric vehicles. We would like to compare them, but we have noted that the different motor power ratings may have an effect on the efficiency, as the lower rated motors had higher km/kwh efficiencies. For example, the 5 kW, 5kW, 3 kW, and 1.5 kW models would have efficiencies of 4 km/kWh, 5.7 km/kWh, 9 km/kWh, and 13 km/kWh respectively.

Would it be possible to normalize the values to remove the factor of having different motor powers, such that the efficiencies are adjusted to where all the motors seemingly have the same strength? And what method would be applicable? I first thought of linearly scaling the efficiency of the smaller motors to the large one using their power rating ratio.

There is also the question of whether normalizing the data is necessary, or if the comparison of the efficiencies with different power ratings is already fair.

Thank you very much!

  • $\begingroup$ the analysis is going to be a lot more complicated than this, because of how motor power, battery mass, design range and cruise speed are all interrelated in complex ways for electric vehicles. I recommend that you refer to the technical literature on electric vehicles and see what "figure of merit" is customarily used in this field. You'll probably learn there which normalization routines are valid and which are not. $\endgroup$ – niels nielsen Apr 4 '19 at 6:06
  • $\begingroup$ noted, thank you, I'll look for additional sources. We have tested the vehicles to obtain these efficiencies, controlling the loading weight, speed, and route of the e-vehicle. It just doesn't seem fair to compare a smaller motor that would consume less power to a stronger motor that could technically handle more but consumes more power. Other sources that list simple e-vehicle efficiencies use kwh/100 km, but they don't factor in the different motor specs, which lead me to question if normalizing the efficiency was necessary in the first place. $\endgroup$ – Calfons Apr 4 '19 at 6:41

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