Benchmarks EV and REx range

[bwilson4web]

Hi,

Benchmarks can be tricky so here are some pointers:

• Standard Day like:
  • 65-75 F
  • little to no wind, best found after 11 PM to dawn
  • Start = End for loop route, avoid tall hills
  • Bi-directional runs over same route, average passes
  • 10 miles (16 km) recommended distance
  • one practice run to confirm no route issues like construction or accidents
• ~30 mph (48 kph) trip meter consumption kWh or MPG
• ~50 mph (80 kph) trip meter consumption kWh or MPG
• ~75 mph (120 kph) trip meter consumption kWh or MPG

Use the three speed ranges to solve a quadratic equation:

• y = a*(v**2) + b*v + c :: v is velocity, y is consumption
• plot the consumption for ~30 mph to ~75 mph in 5 mph increments
• avoid going outside of the speed range in the curve

Doing your own benchmarks, you can quantify the improvements (or loss) of tuning changes. This is completely independent of EPA metrics but specific to your vehicle.

Bob Wilson

[Piotrsko]

Note: standard day for aircraft has a much lower temperature iirc, 59f. Not sure what difference that makes in an electric vehicle with cooled batteries.

Otherwise, cool concept

[bwilson4web]

I agree about 59 F but I've shifted my temperature range up to avoid using the heater. My BMW i3-REx uses electric heaters and that eats into the range.

I probably should mention turning off or minimizing all optional loads:

• A/C or heater OFF - heavy electrical load
• brights OFF - the LED low beams when testing at night IF safe

I didn't mention calculating the 'density altitude' so you correct for temperature and altitude changes. But I don't look forward to explaining how it works.

Bob Wilson

[Piotrsko]

There's density altitude app computers for your phone, but they require an accurate base altitude. High air temperature tends to make the air less dense which is a minor drag improvement but can also make stuff draggy as boundary layer can go non laminar.

Heaters in Huntsville? Until it gets to below 40f and I had to take the F250, I wore a coat. Didn't have the heat efficient so window defrost was the issue.