Thank you for your very helpful graphs and analysis. Very interested to note that Aero Drag Consumption does not increase as dramatically at freeway speeds as I expected it would. Can you explain why the absolute (not percentage) Ancillary Systems Consumption is slightly greater below 25 than over 30?
The ancillary systems energy consumption is from a constant ~1kW power usage so it grows in significance as speed decreases.
There's always seems to be confusion between power and energy consumption. This is where many people get tripped up, myself included. Here are two more graphs of Power vs Speed [kW vs mph] next to the original Energy Consumption vs Speed [Wh/mi vs mph] graphs. (I previously mislabeled them power consumption, argh!) These graphs show results using the same model and input assumptions.
The graphs on the left show the energy consumption, which is
energy needed to go a given
distance, plotted against speed. The graphs on the right show the
power needed to go a given
speed, plotted against speed. The key is that as speed increases the time to go a given distance decreases.
On the left, you can see the
aero drag energy consumption is increasing as a square of speed. The exponential growth in the equations is a V^3/V term that simplifies to V^2. On the right, you can see
aero drag power increasing as a cube of speed. The equations have just the V^3 term.
(It might be interesting to note that the power vs speed graphs show four different power relationships. The ancillary systems power is constant over speed, a V^0 term. The tire rolling power is linear with speed, a V^1 term. Drivetrain power is a function of aero drag and rolling power and so is a V^2 term. [This is not strictly mathematically true, but close when aero drag and rolling drag are similar.] And of course aero drag power is a V^3 term.)
Ultimately, the power vs speed graphs on the right are not too relevant for discussions about EV range and efficiency. What matters more is how much energy is needed to go a given distance, as shown in the graphs on the left.