Lobster wrote:
I'm thinking of buying an 12V - 240V for the car, to enable me to
charge/run devices such as a laptop / mobile phone(s) / AA batteries for
gameboys & camera etc etc while on the road (one at a time!); they seem
to be as cheap as chips these days and this would enable me to use the
standard mains chargers for all the above devices rather than buying
separate low voltage kit to connect each of them up to the cigar lighter.

Sounds good in theory, but are there any gotchas? Eg, safety? Does it
run a car battery down more to power up a laptop via a 240V inverter
than directly to the cigar lighter? etc etc

A lot of laptops need more than 12V so you would still need a DC-DC
converter to run from the cigar lighter. It then depends on the
relative efficiencies of the inverter and the DC-DC converter.

By "on the road" do you actually mean driving? If parked then just be
careful your battery can withstand being discharged repeatedly.

MBQ