The question is what voltage DC does your PC run on? It probably has a power adapter from 240vac to dc into the pc. Many run on 18v some on 12v.
The 12 v requirement is not easy to meet as it will require power very close to 12 volts. Where your boat battery will probably vary from 14volts when motoring to 11.5 volts near discharged battery with engine off. Some adapters are available which will take the 12v battery in, convert to AC, transform to higher voltage rectify to DC and regulate it to the required voltage. I think many people find it easier to buy an invertor to provide 240 vAC to feed the standard adaptor/charger. This is somewhat less efficient ie more battery power wasted but it does give you a 240vAC supply for other low powered gadgets. Sorry not in UK so can't direct you to suppliers etc though a search in the past on this site may help.
I have used a low power (150-250w) 12v to 230v inverter to power my Acer PC. The nominal charger output to the PC is 18.5v. This has worked well but it is not very efficient . I recently looked for an alternative in the form od a DC-DC converter to go from 12v to 18v and found the ideal gadget from a local electronics supplier Jaycar. The spec is below. go to www.jaycar.com.au and enter the stock code number MP3462 into the keyword search field and it will take you to the item with a picture. It is wired with a plug for a cigarette lighter socket but that could easilybe removed to allow it to be wired into the boat's DC system via an appropriate fuse or circuit breaker.
The unit comes with various plug adaptors for the PC end and has a slider switch to set the output volts. The output is very close to the value indicated on the switch position. It works a treat and has lower quiescent current than the inverter.
These are made in China and imported by Jaycar but I don't know the brand offhand but it is unlikely to be exclusive and I would expect identical units to be sold in UK under other brand names through similar electronics stores.
Run your laptop computer from your car battery. This switchmode regulated 13.8VDC input DC- DC converter power supply will increase the voltage to run a laptop computer from a car.
- Input voltage 12
- 15VDC car battery power
- Output voltage features 7 different voltages to suit most laptops 15V, 16V, 18V, 19V and 20VDC @ 3.5A regulated and 22V, 24VDC @ 2.9A regulated
- Supplied with 5 changeable output plugs: 2.1 x 5.5mm, 2.5 x 5.5mm, 3.0 x 6.3mm, 1.4 x 6.0mm, 1.7 x 4.75mm
- Stabilized output, low ripple and low interference
- Short circuit and overload protected
- High efficiency and low energy consumption
- Power LED monitor
WARNING: Be extremely careful, and triple check that you have the output plug connected with the correct polarity to suit your laptop. Connecting with the polarity the wrong way will damage a laptop computer, If unsure seek professional guidance.
I have alway run my PC's in the boat with a simple car adaptor for the particular PC (even a pc wanting 18v!) with no problem. At first I used the smallest Prowatt inverter to change 12ish DC to 22OAC - worked ok but the amps used were high.
then just started buying the relevent car adaptors which have a voltage controller in them
going from ships 12-13-8 (at charging voltage) into 240V AC via an inverter and then back down via the PC's power supply to 12v or 19v DC introduces inefficiencies into the system with lost current in the form of heat in the inverter and the transformer.
Better as suggested above to use a DC to DC regulator.
I am on the hunt for a ships supply to 5V DC to DC converter for my boat project which uses a tiny fanless PC (the motherboard is the same footprint as a 3.5" disk drive).
I use a Vanson SDR-70W, which is switchable to 7 different voltages and came with 5 different adaptor plugs, so it will suit almost any notebook computer. I reckon it's worth getting a universal power supply because it's likely to last a lot longer than the computer and will probably work on the next computer I buy. Also runs on the sockets in airplanes. Voltage seems very stable. About £37 from Euro Batteries, who don't specifically list it as Vanson, although you can see the brand name on the pic.
Targus do dc/dc adapters for computers. The problem is getting the right tip that fits your computer. I have one of these adapters but have changed computer and they dont yet do a tip for it ! But if you search the site you can see the list of tips, if you're lucky you'll find a match.
I recommend the use of a DC/DC converter. This provides the cleanest power without a double transformation that wastes power.. Maplins do one, and I have also bought one from ebay, but best source I know is here
It has various connetors and 'fuses' to cover voltages from 15 - 20V ... so caters for most notebooks ......... but check connectors as some notebooks have strange power plugs ... Maplins again will help when you go for it ....
I have one and it's very good - powering my Acer, Maxdata, IBM Thinkpad, HP etc........ ok not all at same time !!!
Best way to go .... I have Inverter and DC - DC ............ the latter is FAR superior and uses less battery .... and it makes no odds about state of battery as long as its in normal operating ranges .... of course not flat though !!!!
The inverter I keep for other uses where 240V is necessary ...