Laptop power consumtion.

[peterb]

My panasonic laptop psu is rated at 5amps at 15.6 volts (48 Watts) input current is .6A at 240 volts. Assuming a power factor of 0.9, that gives an input power of about 130 watts, so the psu is only 40% efficient. Better bet for the boat would be to get a DC to DC converter to convert the 24v DC to whatever voltage the laptop requires (most seem to have 17 or 18 volt input)

A simple voltage regulator in a box would do the trick, although you may want something more sophisticated that provides overvoltage prorection on the output should the regulator fail.