Quote:
Originally Posted by bennelson
The Solectria Force was a factory built electric Geo Metro which ran an AC system. Those used 13 group 27 batteries and could go about 40 miles. They also had regenerative brakes.
|
It would be interesting to see what speed that 40 mile range is quoted at. Some of the range gain is due to the efficiency gain with using an AC system vs DC. If you can lower your Wh/mile (effectively your electric mpg), you can go farther. The thing about electric vehicles (especially with regen) is Wh/mile is more proportional to speed than almost anything else. Theres no idling to harm low speed operation, plus with regen the start/stop isn't as big a penalty. That really only leaves rolling resistance and aerodynamic drag. Of those two, aero drag is a much larger energy hog, so aero mods will be key to reducing Wh/mile and therefore range at higher speeds.
If I were going to build a metro, I'd get the biggest capacity 12V batteries I could (group 31 batteries are usually just over 100Ah). I'd try to get up to 144V. This will give you 14,400 Wh capacity. Now, you should really only use half that (7,200), so the range will be ~24 miles. You'll get more range at lower speeds, and less at higher speeds.
At that point, you're already adding ~850lbs to the Metro and I don't know if I'd go much further than that. The only other way to increase range from the same size battery pack is to further increase the voltage. This reduces the current needed to accelerate and maintain the same speeds. The efficiency gain comes from reducing the
Peukert effect. However, finding components (motors & controllers mainly) that handle higher voltages isn't the easiest thing while staying with DC motors.