Dave Plowman (News) wrote:
In article ,
Michael A. Terrell wrote:
As a thought - what is the DC requirements of the Laptop ? - it might
not be necessary to go up to mains voltage and then back down.


Not a good idea. There can be spikes of up to 400 volts in an
automotive electrical system. Then there is the possibility of a 'load
dump' which happens when the voltage regulator fails, or a loose battery
cable.

Makes you wonder just how all the various computers in the modern car
survive...

Fat wires directly to the battery has always served me
well in a number of instrumented cars.
Only one accident with a blown regulator in a generator,
suddenly about 100 volt instead of 12 volt.
That was over a period of 40 years.
The battery works like a rather big capacitor.