Just experienced a flight where on the 739, the power ports underneath my E- seats turned red after successfully charging my laptop for about 30 to 60 minutes or so. So then I turned to the row ahead of me to connect my ThinkPad and while they didn't turn red, the green light turned off and wouldn't charge my laptop. This was on a half full plane, too. It'd be nice if they can put the max wattage/current draw on the label that says power ports are available in that row. I don't even know if Lenovo sells lesser wattage AC brick adapters.