Powering laptop etc in car from inverter?

Smaller, but not tiny. Many laptop batteries are >10% of the capacity energy-wise of the car battery.

The 40 watts was just following on from ab's post - not meant to be an actual figure for a laptop.

Car bateries are 40-70Ah, and at a nominal 12v, that is 480-840Wh.

Giving and expected uptime at npominal 80% eficiency of say 4-8hrs roughly.

Total bollocks as well.

But...... Probably most overlooked is the fact that laptops (when I were a lad) were set as default to offer no power saving features when plugged into a 240v supply. i.e. Set as default to "maimum performance" compared to "maimum battery life" when on internal battery.

So unless these default settings are modified to offer the same economy of energy when on both battery and mains there will be a significant increase in power usage.

I would guess.

Dave Plowman (News) ( snipped-for-privacy@davenoise.co.uk) gurgled happily, sounding much like they were saying :

Depends on the laptop.

Mine (big widescreen) whinges if it's on a 65w psu, and came with a 90w. Others come with a 45w psu.

I've never come across a laptop psu that wasn't clearly labelled, though...

yea total bollocks, then buy one and read the instructions, i have had two in the past, and damaged them by keep starting the car without turning them off.

Now why doesn't that surprise me..?

just looked at my psu and it is rated at 1.6amp at 240v input and 3.5amp at

In message , aussie bongo writes

And only a tit would say "around 2.222222222222-amps"

that's an extremely precise, practically unmeasureable value

I'm pretty sure it's not actually measurable at the moment.

well with the watts and voltage and a calcalator = amps

You're failing to take into account quite how badly designed most "cheap" invereters are, they're realy easy to break. Might would have been better than will though.