Is the 4 hour laptop battery with or without wifi/bluetooth on? I've stretched a 3 hour charge to 5 hours on older laptops by reducing resolution, lower brightness and sometimes calibration settings that remind you of Windows XP OS wise, but video wise, is unchanged. An hour or two extra is still nice.
That and spending time to disable unneeded resource usage programs would help too.
This is all perhaps moot if you can plug in your laptop though. +1 to the portable battery charger suggestion (better yet, try to borrow one if you don't need it all the time/ buy and return
)
Also, are you using for the full 18 hours? For such flights, I usually just need to entertain myself 5-6 hours and conk out for the rest. More than enough via ipad and laptop battery life.
I'd suggest a Hootoo Tripmate Nano for your ipad, but I don't think using wifi is ok on a plane just yet...
But the following is an attempt for the dumbest suggestion in the thread:
http://9to5mac.com/2014/08/22/makesh...-iphone-video/
Might get around the small screen issue by keeping it closer to your face.
