http://www.cockeyed.com/science/power_use_database/laptop.html - I don't know if this correct or not.

My battery charger, if called into the mix would LIKE to draw more than that for the Dell mobilee that I have. It might not get that much power out of something, but it will be "asking" for it. If we had it on a cigarette plug, it would be limited by the plug in most cases. That's why you should use it with an inverter, in my opinion.