A DC inverter basically undoes the process of those power adapters, allowing your gadgets to be powered by sweet, sweet direct current, which is the kind of power generated by your car’s power port/cigarette lighter and most airlines. This
120 Watt Auto-Airline Inverter
will let you plug your gizmo into a standard power outlet, and will itself plug into a car or plane power port, meaning you no longer have to rely on your laptop’s limited battery.
It’ll run you $60, but it measures a fairly compact 5 1/2″ x 4″ x 1 3/4″; no word on weight though, and inverters can be kind of heavy.