Dave Plowman (News) wrote:
In article ,
Sjouke Burry wrote:
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.

To get 100 volts you'd need not only a faulty regulator but a faulty or
disconnected battery. Turning the average alternator hard on only usually
results in the high teens volts wise. Although I've no idea what happens
with some of these modern ultra high powered water cooled types. ;-)

At those heavy overloads the battery will form a gas layer
between electrolyte and electrode.
That gas layer will act as high resistance(for a short time),
long enough to explode the caps in a number of convertors.
After servicing about 12 supplies and an assorted 10 opamps,
we were back in bizness.
The generator survived.
The battery as well.
The regulator needed two transistors and a new zener diode.
But spikes as mentioned? Never a problem.