Electric Bug: Driving and watt-hours per mile

Electric Bug

I now have over 3000 miles on my car. Up till today, the only problems I have had have been with the IOTA DC-DC Converter. I’m supposed to have a replacement soon, as my IOTA may fail again at any moment.

Now that I have some driving experience, I have a better idea of the range. It’s not good to say that an electric car gets X mile range, since X various by many factors. Those factors are: how heavy you are with the pedal to accelerate, how hard and often you brake, how many hills you drive up and how fast you drive. I have one big hill on my commute (or, when I go *anywhere*), so I can never remove that factor, and I always want to drive at least the speed limit. But I can control how “soft” I drive.

If I drive the car “soft”, meaning reasonable acceleration and driving at the speed limits on the freeway (usually 65 mph), I could get a 100 mile range to 0% State of Charge (SOC). Last Sunday I drove 64 miles according to my odometer (or, about 62 miles according to google maps). The BMS said it took 122.3 Amp-hours and the SOC was at 39%. This drive was mostly at 65mph, aside from the 2 miles driving up my “driveway”, and then going 50-55 up and down highway 17. I had maybe one stop light each way on my trip. 122.3Ah * 48 (number of cells) * 3.2V (nominal voltage per cell) = 18785 Watt-hours (18.8kW). 18785.28Wh / 64 miles = 294 Watt-hours per mile. The batteries are rated at 200Ah. So: 200Ah*48*3.2 = 30720 Watt-hours of energy in the battery. 30720Wh / 294Wh/mile = 104.5 miles.

So, a good “soft driving” estimate for my bug, including a large hill and mostly 65 MPH on the freeway, is 104 miles. Generally, I don’t want to do this, as taking the battery lower than 20% is not good for cycle life. I also don’t have my BMS setup to limit power when voltage drops to a certain level, so it is dangerous (meaning, I could cause damage to expensive cells).

If you are doing a bug conversion, use about 300 Wh/mile as an estimate for what you can get. I rarely get better Wh/mile, but that is because of my huge hill I drive up. Wh/mile would be better if I didn’t live in the Santa Cruz mountains.

Now, if I drive “harder” I can get about 375 Wh/mile. That’s about an 82 mile range. So, I can probably safely say my range is from 70 to 100 miles per charge, but I probably won’t want to go more than 80 miles to keep it “on the safe side”.

Previous in Electric Bug
Charger Not Charging
Next in Electric Bug
Back on the road again

Leave a Reply

1 Comment threads
0 Thread replies
Most reacted comment
Hottest comment thread
1 Comment authors
Stu Recent comment authors
Notify of

I love your articles. Leave it to a programmer if you want the real nitty gritty on actuals and a very complete explanation. I’m in Florida. It’s very flat here and I drive about 30 miles a day rarely exceeding 50mph. I think your bug would be incredible here. You would however need A/C which would be a drain. I am a long time VW guy and will sometime soon do a conversion.

As an Amazon Associate I earn from qualifying purchases.

(c) 2008-2020 Corbin Dunn

Privacy Policy

Subscribe to RSS feeds for entries.

91 queries. 1.538 seconds.

Log in