Optimizing long distance travel speed vs charging time

[JoulesThief]

This is a project for the algebra and math gurus to think about.

First some basic assumptions.

Level 2 208V charging at 30 amps is all you can find on this long distance trip.

The trip is all two lane highway, with a maximum speed of 65 mph posted.

You need to make 300 miles a day.

You don't have 24 hours to do 300 miles.

What is the shortest amount of time you can do the trip in?

What is the optimum speed to travel at, to maximize miles per kwh, and minimize total charging and trip time?

 

[miimura]

To do this properly, you need the efficiency (mi/kWh) vs. speed. Something like this Range Chart for the Leaf would be needed. I don't know of such a resource for the e-Golf.

 

[f1geek]

Assume the weather is nice and the road is flat. Let's take the extreme case of crawling along and getting 6 mpkWh - I'm guessing your average speed would be about 25 mph. This will get you 134 miles (5.4 hrs) assuming you drain the battery down to 8% of the full 24.2 kWh (drain down to 1.9 kWh). Stop and charge at 6.2kW until 95% (23kWh) will take 3.7 hrs (last 5% will take another 30 minutes). Next stretch at 6 mpkWh will only get you 127 miles, again at 25 mph (5.1 hrs). You have 31 miles left. At 65 mph, you'll be there in 0.5 hrs. Total time: 14.7 hours. Bring a good book and a book on CD and you'll be plenty entertained. Of course, at this speed, you may end up getting in a crash as you are a moving chicane.

If you drive at 60-65 mph, a somewhat reasonable speed, you may average 3.5 mpkWh - 78 miles, stop for 3.7 hrs, drive again for 74 miles, stop for 3.7 hours, drive again for 74 miles, stop for 3.7 hours, drive for 74 miles and you at your destination with a battery at an 8% state of charge. Total travel time: 5 hours driving, 11.1 hours charging=16.1 hours.

What's near the optimal? probably driving at 50 to 55 mph and get closer to 4 mpkWh, the trip would be 89 miles (1.6 hrs), stop for 3.7, drive 84 miles (1.5 hrs), stop for 3.7, drive for 84 (1.5 hrs), stop for 2 hours (enough to get there) and drive 43 miles (0.8 hrs). Total time: 14.8 hrs.

Good luck!

 

[JoulesThief]

Let's add 1700 vertical feet in the first leg, and 74 miles for the first leg. How slow do I need to go?

Lets add 1200 feet to the second leg, and about 90 miles for the second leg. How slow do I need to go?


Let's add 400 feet of elevation to the third leg, and about 84 miles.


Am I dreaming, as this is layed out as the charging opportunities present themselves. That's the first 250 miles, the last batch of miles I am not too worried about.

I did come across this, might be useful somewhat with Nissan Leaf Beta mode, although I think the e-Golf does better than the Leaf in the drag dept and miles per kwh. Probably 10 to 15% better. https://evtripplanner.com/planner/2-5/?id=ogms