Hi Jinx,

The LEGO MiniMotor is pretty efficient ... if you connect two of them
electrically and turn one of them, the other does a very good job of
tracking.  Part #5225, US$17.50 from LEGO Shop at Home, post paid.
800.453.4652

 - Nick -

> Jinx wrote:
>
> I'm investigating a weather station / data-logging project using an
> F84 or 508 plus RAM or EEPROM. The components and mechanics
> aren't a problem, but looking at the cup anemometer prototype I
> wondered
> if a second one could be used for turning a small motor to top up the
> battery. Is this a viable method ?
>
> How efficient is a motor when it's used as a generator or are the two
> merely the same device ? Presumably to get the same drive V & I out
> of a motor you would have to turn it at its (normally) driven speed
> and
> lesser V & I would be had at lower speeds.
>
> Usually I'd use an el cheapo solar cell but in this app there's the
> little
> added challenge of perhaps using something else. Has anyone tried
> this method of small battery charging ?
>
> Jinx
>