Originally Posted by pdhenry
I don't disagree, but the capacity of the airplane's power port is also to be considered. some laptops consume more than the output capacity of the outlet when running and charging.
Correct. I think typical power points are 70W on planes. Coincidentally, that's what iGo's original Juice70 series supplies. They've got a new version, the EverywherePower7500, which will supply up to 90W when plugged into something else (wall power or 12V power point in your car).
I'm not 100% sure, but I think that your typical "business-class" laptop will draw less than 70W power even while charging the battery. Since I've got my stock IBM supply and my iGo at my desk today, I'll even do a little test on my Thinkpad T40.
I'm drawing my battery down a bit as we speak after unplugging. Just sitting here typing, I'm drawing about 15W, jumping to 21 when I do something that hits the hard drive. I don't have any DVDs with me, so I can't test that.
I ran the battery down to 90%, then plugged back in the stock power supply - reported wattage was 21W. Then I switched to the iGo, reported wattage was 21W. So, all things being equal, a fairly standard laptop's power draw is pretty reasonable. I've got a 73W-hr battery.