We bought a $90 Coleman 12V icebox for our recent 9-day trip and it
worked out great.  We kept a couple of gel cooling packs in there to
keep the thermal momentum going when it was unplugged and we had no
problem with premature spoilage, molding etc.  It helps to keep a
couple of beers in there too...for thermal momentum, ya know.  :-)

They say not to keep it plugged in for more than an hour without
running the motor.  So when we popped into a store or a quick meal, I
kept it running.  Overnight it either got unplugged or I was hooked
up to AC and used a battery charger and aux battery (required per
instruction) to keep it going.  They also sell an AC adapter pack.

BTW, if you flip the polarity, it becomes a food warmer.  This is
officially sanctioned and there's even a switch to make it so.  When
you use this thing, you _know_ that the billions of $ in Space
Shuttle research is working for you.  :-)

-Karl

Karl and Kristina Bloss, Trexlertown, PA
'87 GL Weekender  "Beverley"
VW shop list: http://www.enter.net/~bloss/vw/vwshops