Originally Posted by
cordelli
In the early days, you could not deliver enough power at 110 watts to run a laptop and still be with in the FAA rules, so early systems were 12 volts.
Power is watts or volt-amps. The same amount of power can be delivered at 110V or at 12V, just with a different amperage. And how the power interface converts it to the end device is really what matters.
Originally Posted by
djk7
My impression is that 12v systems are used because they are safer to the user than 110v. A 12v system isn't going to give a noticeable shock, a 110 zap will wake you up, and can potentially be harmful.
If you really believe that then go grab the terminals on a car battery. Soak your hands in saline if you really want the full experience. You'd essentially be defibrilating yourself, even only with as 12V system.
There are a number of differences in the efficiency, wiring and other factors between DC and AC power, but the same amount of power can be delivered through either system.