You will likely want to find a transformer for your laptop that can plug
into a 12V outlet (like a cigarette lighter outlet in a car). Depending on the brand of PC, the manufacturer might already make such a beast, I have a Lenovo and they make an adapter that I use on our boat. If the manufacturer does not make a 12V transformer, you can check at a store like Radio
Shack as I know they sell "universal" transformers that you can plug
into multiple voltage sources, can set the output voltage, and select the appropriate tip and the polarity of the tip for your laptop.