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Recharge Calculator

I've been running through the math of "how long am I going to be stuck at " to get enough juice to move along. When I'm driving around town, it's easy-peasy because I can just come home at the end of the drive and plug in. It's the less common case -- the road trip -- that inspires this.

In any case, I wrapped all this up in a simple Web app at:

http://evcalc.calicowebdev.com

I also put the code on GitHub here:

https://github.com/sxross/ev_charging

Why I'm mentioning this is:

  1. Somebody might find it useful.
  2. I'm not an EE. Some of you are. I don't even know if my numbers match reality.
  3. If it is useful, it's open source, so for those of you who are devs, fork it, hack away to your heart's content and send me pull requests (be sure to look at the README)!
    (If you're not a software dev, this probably sounds like Greek.)

Any comments are mucho appreciated. I may have missed the mark entirely. By the way, this is not supposed to be a replacement for or duplication of the keen little thing Tesla has that allows you to figure out how much your charging will cost based on your average drive. It's supposed to figure out your estimated wait at a charger and answer questions like: Is it a long lunch, a day hike, an overnight?

It's a good start, but normally I don't know how many Watt-hours I need to charge before I am "full," without doing my own math. It would be more useful if one could simply enter the current rated miles (as displayed on the instrument panel), and the target charge level (50-100%), and of course the battery size (40, 60, 85).

I think the default charge rate should be 40A rather than 50A, which is what the Universal Mobile Connector (UMC) draws on a 240V 14-50 outlet.

See http://evtripplanner.com/calcs.php for some reference numbers and formulas for calculating how long it will take to charge. E.g. at 240V 40A the charger adds 21 miles per hour of charge to the rated range.

Finally, I selected 340 Wh/mile as my long term usage (the default), but the calculator displays "Assuming a normal driving habit of 325W/mi, you will get 61.54 miles." Shouldn't it show 340 Wh/mi (note: it's Wh/mi, not W/mile).


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