On Thu, 2 Jan 2003, Isaac Taylor wrote:

> Make of this what you will, but when I was working at Boston Volkswagen
> last summer and these solar panels started coming in (they work great, by
> the way -- I gave out a few to friends and family) there are very clear
> instructions from VW in every new car to not leave the solar panels
> plugged into the cigarette lighter once the vehicle is running, at risk of
> electrical hazard and potential fire. I guess the theory is that if the
> car is on, or if your cigarette lighter in an older car is wired to
> provide power even when the ignition is off, that rather than charging the
> battery, the current flow reverses and heads into the solar panel.

It must be related to the higher voltage when the car is running.  The
cigarette lighter providing power even when the ignition is off can't be
the issue -- if the cigarette lighter is disconnected when the car's off,
the panel won't charge the battery!

             _ _
  __ _ _   _| | |  | David M. Brodbeck (N8SRE)              Ypsilanti, MI
 / _` | | | | | |  +-----------------------------------------------------
| (_| | |_| | | | @ cyberspace.org
 \__, |\__,_|_|_| "To the optimist, the glass is half full.  To the
 |___/             pessimist, the glass is half empty.  To the engineer,
                   the glass is twice as big as it needs to be."