Charting EV performance

[bwilson4web]

This graph shows my 2019 Model 3 performance by using the EPA roll-down coefficients and a recent battery benchmark. As a function of speed, mph, starting with a 100% charge, this gives: (1) range miles; (2) time minutes, and; (3) Wh/mi.

Unlike a single speed, 70 mph benchmark, this gives predictable data to choose what speed to reach what distance. The Wh/mi corresponds to what the car displays.

Operationally, this is best for the first drive of the day to reach the furtherest Supercharger. Thereafter, we use this to tradeoff charging time to shorten travel time.

Bob Wilson

 

[pictsidhe]

Interesting.
I found the EPA dataset for all recent vehicles. I see spreadsheets in my near future.
For my '23 Mini, assuming 95% energy conversion efficiency:

Mph. Drag. Wh/mi
30. 54lb. 112
60. 108lb. 222
65. 118lb. 245
70. 131lb. 272

I couldn't see a m3 performance in the 2019 set.
2019 m3 LR also using 95% conversion efficiency:

30. 57lb. 118
60. 98lb. 205
65. 108. 225
70. 119lb. 249


From those numbers, the '19 M3 LR is about 5mph faster at highway speeds for a given mi/kWh than a '23 Cooper SE. The Mini has less drivetrain/tyre losses than the M3, but loses aerodynamically. Less weight also means less regen loss. This is why they beat Teslas in city driving, but on highways, you win!

 

[pictsidhe]

I've been interested in finding this info to estimate optimum speed for shortest trip time. The faster a car is driven, the more time is has to spend charging.

With minimal charger detour time, it's actually very close running between 10 and 80% and 60 or 70mph. Add in detours to get to chargers and get the damn things to start and there is an advantage to going slowly...