RANGE VS MPH
Of the different approaches, I decided to run three, 10 mi benchmarks and record the trip meter metrics:
- 25-35 mph - low speed needed to include vehicle overhead
- 45-55 - middle, urban speed needed for around town metrics
- 65-75 mph - high speed to get aerodynamic effects
I plotted these three points and used the Excel trend line for a quadratic equation to plot the kWh consumption as a function of speed:
- Max mi - normally the battery is partially charged so there is 'head room' to absorb regenerative energy. This improves mileage in stop-and-go traffic.
- 90% line - a little optimistic, I now use 85% giving a 203 mi range around town. It is so much I no longer look for 'free' chargers as I can drive all day yet return home with +50 mi and recharge. If free charging is available, I'll use it but it no long drives my shopping choices.
If leaving for a cross country trip, I set the limit to 100% knowing the next day I'll be on the highway and regeneration will play little or no part. But then we drive based upon the "reserve range."
- battery range - a fairly accurate estimate based on recent driving, this becomes the 'no further' indicator
- mi to destination - the navigation unit, sensitive to terrain, gives a fairly accurate miles to go which must remain less than the battery range. If I have the time, I leave with 30-40 miles reserve between the two. At 20 miles, I begin slowing down as best I can. At 10 miles, I start looking at secondary charging options like RV parks, distribution, and J1772 chargers.
Bob Wilson