Tong Family

If you are a nerd, and have range anxiety, how do you know how much charge you will really need. Here’s a way to figure it out

1. Get a login to teslafi.com. It tracks your real world performance in minute detail. In particular it tracks the major variables like temperature and even wind.
2. Get a login to abetterroutplanner.com and plot a long highway route. The key thing is to hit more settings and let it know the weather, temperature. Also take the default car performance based to your car type. The weight in the car etc.
3. The variable you are trying to figure out is your nominal watts used per mile st 65mph. This is what predicts your driving style.
4. Note that another key variable is your average speed. Are you at 100% of rated limit or not. The faster you go the worse your efficiency.
5. As a check get Stats on iOS as the compare you with other drivers inefficiency by class of car.

When we did this here’s what we found.

Model X

For the Model X 100D, the nominal is 386W per mile at 65 mph. However on these runs we found we much closer to 300Wh/mile.

So for a highway drive we have 2:34 hours and 73% usage at 48F with light rain.

The model at 104% and 386 W/mile predicts 2:38 hours and 78% usage.

Do then running a quick test shows the numbers should be 105% and 350W/hr. So much better than 386W/hr nominal.

This is a winter condition so taking a spring trip we have 3:06 hours with 58% used at 85F

Finally a spring trip with a different driver 2:33 hours with 58% used at 65F from 97 to 39%. This is quite different at 105% of speed but consumption is 305W/mile

This shows how the driver matters a lot so when planning do an average of who is driving. The main difference by the way is not speed but whether you are drafting. The model x is a big car so it helps a lot to be behind a semi

Model 3

For the Model 3 Performance, nominal is 293W/mi but we were much more efficient. The prediction was 91% to 23% or 68% in 2:42 hours. The actual 2:34 hours going from 91 to 27% or 64% consumed. So both faster and less consumption. That is 3% higher than speed and 6% more efficient. With dry conditions and temperature of 58F

So at least for this run the values should be 105% and 275W/mi. so plug that in.

This won’t be exact but then input in abetterouteplanner.com and then do a binary search first for time adjust the reference speed and then for charge used. In our case the values were 105% of reference speed and 265W/hr.

The nice thing about teslafi is that it shows you common long routes so do again for another condition and average.

Now this varies by driver and weather so it’s good to understand that.

So in another run, the temperature was 14.8C or 58F and it was in 2:38 hours with 64% consumed as well and slightly faster than 2:42 predicted at 103% of speed limit and doing some goal seeking 263W per hour.

So that’s not a bad value. Do 103% and 265W to get something of a pessimistic average.