12v Laptop Adaptor

Dodger,
Ouch! 6.3amps is quite a lot for a laptop.
The power pack converts your AC mains power down to 19volts DC, a requirement of your laptop. If your laptop is using the full 6.3Amps, then this corresponds to about 120 watts power consumption (6.3 amps x 19 volts = 119.7 watts). So allowing for inefficiencies of your power pack, you will need about 130-140 watts input from the mains. This also means that you will need at least this power if you are using a 12volt - 240 volt inverter. Without getting too technical, in practice, you may need a lot more than this power capacity in the inverter.
140 watts from the inverter into the power pack will require about 160 watts input from the 12v supply, or about 13 amps.
But the good news is that the laptop only requires this 6.3 amps briefly, when the internal battery is charging and all drives are running. You may find that the consumption will drop to about 1/3 of that once up and running, and battery fully charged. Even less again if you have set up power saving settings in your laptop.
Alternatively, Dick Smith's and a few others sell a direct 12v - 19v converter, which cuts out some of the conversion inefficiencies of using both a power pack and an inverter. Tho you might have trouble sourcing one that supplies 6.3amps. If purchasing one of these, you have to be very careful that you set it to the correct output voltage and get the polarity right. There are no second chances if you get it wrong.
Gerry

Hi Dodger
I had a similar problem when looking for a power supply for the IBM Think Pad. I ended up getting an Inverter 300watts which powers the laptop with ease.
Ray

Hi Dodger, the inverter may not be the most efficient way to go but it is by far the best idea if you have anything else that you can use it with, such as camera battery charges, electric shavers and so on.
The uses for an inverter is only limited by your imagination.

The size of the inverter is the only thing you have to decide on, and that should be based on your perceived uses.

I have 2 different inverters that I use regularly, a 130 watt that I keep in the 4by at all times, for charging camera batteries and to run my lap top.

I also have a 750 watter at home and unfortunately get to use it a lot because of all the blackouts we have. I use the 750 to power a lap lop, wide screen TV, VCR, DVD player and 2 low power fluros all at once. The longest I have used this set up is 11 hours straight using the 4by’s battery and had no trouble starting the 4by next morning.

Hopefully, this will give you some ideas to ponder.
Cheers

Dodger
I have a Dell Inspiron 5150 which runs from a 130 w AC adaptor with an output of 19.5V, 6.7 A and inputs of 100-240V, 2.5A
Had the devil's own job finding a 12 volt dc car adaptor for it. Eventually tracked one down specifically for the 5150 from Lind Electronics (www.lindelectronics.com) in the good old US of A. Arrived yesterday. Not tried yet.
Site worth a look I reckon.

I use a 12V to 19V adapter which I think would be more efficient than converting to 240V then back to 19V (not to mention cheaper).
Cheers
John