More and more motorhomers are using a small laptop in their day to day travels to keep a diary, access the internet and digital photography etc. As so many of us free camp, and not all generators are suitable for use with the delicate electronics, you need to find other ways of providing power. The options are investing in a Targus - a device developed for air travel mainly in Business Class as you need an Empower outlet on your seat. It converts 12 volt DC to 19 volts DC and costs around $250.00. Next you can rig up an inverter - this converts 12 volt DC to normal, but high quality 240 volt AC very suitable for computers. This is a good alternative as an inverter is a multi use device, and once you have one you will truly wonder how you camped without one. You MUST have a pure sine wave unit though - a bit more expensive and you have a double lot of losses going down tis track. The DIY section on this site gives a lot of info on installing an inverter for use with a computer..

Doing it on the Cheap!

Now the next option at first glance might sound a little naughty, as it seems something isn't quite right. You can actually run your computer straight from your normal deep cycle 12 volt battery bank. with no extra electronics needed at all. All you need to do is install a cigarette lighter socket or similar and then make up a lead with the correct plug to suit your laptop DC input. You get these at Dick Smiths, Jaycar Electronics etc. It is a good move to rock in with your laptop as there are several styles. We only have experience with Toshiba, Amstrad and Sony. The Toshiba uses a bog standard plug. Things get more hairy with the Sony as the centre lin is only 2 mm. Make certain that the centre hole is not too big on other brands. Please don't attempt this job if you are new to soldering as mixing up polarities and minor shorts will kill your computer. So why does this work when on paper it suggsts it wont? Well Collyn Rivers explained it beautifully.

The Thoughts of Collyn Rivers

"Portable computer equipment usually have internal nicad batteries. These need a somewhat higher charging voltage differential than lead-acid batteries (typically 18-19 volts for a typically 14 volt battery). Nicads produce about 1.3 volts a cell when fully charged - and drop to as low as 1.0 volt a cell when 80% discharged (totally OK to do).

Thus laptops designed to run from 12-14 volt power supplies will run happily from 12 volts DC. Those that need the higher (14 volts) will not be harmed by 12 volts - as they get a lot less than that before the nicad goes flat. I vaguely remember some early laptops that ran from 5-7 volts. If any are still around - they'll need a 6 volt supply.

The power savings are quite considerable, as a great deal of the energy is lost through inefficiencies incurred twice - firstly in the inverter, and secondly in the 240/12 volt black box. I've had my standby Canon BJC-70 printer working like this since 1997. Vehicles with 24 volt systems can do this via a 24/12 converter such as those from Jaycar."

As we are working with expensive equipment it is a good idea to upgrade from the el-cheapo cigarette lighter sockets to marine grade or better still go to a proper 12 volt polarised plug and socket as shown on the right above. You can buy these at Camec etc. Doing this ensures a steady current flow. The photos below left show the various configurations of lighter sockets. The photo above left shows the "trap" with the Sony plugs as these are much harder to source than the Toshiba one shown at the left of it. The picture below right shows the excelent detail shown on the Sony power supply. The picture of the plug shows very clearly that the internal pin is positive. We STRONGLY suggest you check this with your meter and then compare it with your lead before using. If you don't understand this please don't attempt this project.

Low Cost Commercial Lead

If you are not into soldering but have a 12 volt cigarette socket in your motorhome there is an easier solution. Pictured below is a gadget from Dick Smiths called a Digitor Cig Plug - DC Plug Lead - cat. P1692 - $19.95. Now you do need to take care with this gadget as there is a REAL RISK of reversing the polarity (plus and minus). What we do when using this type of plug in adaptors is to put a couple of drops of Araldite on the plug to stop removal. The plug comes with an on/off switch, is fused, has a small green LED and it has a curly cord which makes your table a bit neater! NOTE:- This gadget wont work with Sony and we suggest you take your laptop with you to the shop.