[ausev] Are EV's too one dimensional?

[Christopher Robison]

On Fri, 2007-05-18 at 12:41 -0500, Nick Barbaro wrote:
> Mike,
> Much better to use a human-powered generator.  If I'm not mistaken, a 
> stationary bicycle could be rigged as a generator to charge the 
> batteries. So if you need to pop down to the store, you just hop on the 
> bike, pedal long enough to charge up your batteries, and go!

I've had a pet project idea floating around in my head for a couple
years, to build just such a generator setup, primarily for demonstrating
to people that alternators and generators don't make electricity out of
nothing. Most of the put-a-generator-on-the-wheel or "windmill hood
ornament" folks who think you can just generate power off of the motion
of the car fail to understand how much force is required to crank a
generator at a given power output. When someone at one of our PR events
comes up and starts suggesting this idea, I think it'd be great to have
them sit down and start pedaling, and then feel the instant drag when a
load (like a 100W lightbulb) is switched on.

In reference to the human-powered charger idea, by analyzing the amount
of energy used by the lightbulb and how hard you're cranking to achieve
it, you'd get the idea pretty quickly that charging a car this way would
take a great deal of very hard cranking.

I understand that a fit human being (i.e. not me) can produce
approximately 1/4 horsepower, continuously. This is about 186 watts.
Charging a typical EV for 40 miles of range at 12 *kilowatts* may take a
little over an hour (the real charge time is longer, since you don't get
the full 12kw at the end of charge). Clearly, you're in a different
ballpark with these numbers.

  --chris