I'm helping a friend out trying to solve some battery life problems with her mbp5,3 15" 2.8ghz c2d. She has an upcoming trip to Germany (approx. 12hrs each way) and wants to use her mac on the flight. On the way back there will be power available and she could use the magsafe airline adapter but not on the way there. The problem is that she reports only 1.5hrs of useful battery life. I installed the trial version of iStat and the battery shows 436 cycles and 82% health. So there are two solutions as I see it: 1) replace the battery -ifixit is out of stock, but I found one at macpartsonline for $191 plus the pentalobe screwdriver from ifixit makes it just over $200, which is more than apple would charge to replace the battery by a few dollars, but I don't think she can have the 3-4 day downtime i'd expect going that route (will verify with local apple stores and if anyone has another source for the battery, I'd appreciate it). Add $50 for the airline adapter and you've got maybe 5hrs on the way out and no problems on the way back. 2)buy a external battery -the only one that seems to be review on MR is the Hyperjuice and those few reviews that I found are mixed at best (and for the higher capacity versions), with some saying it's great others saying it's the worst. This route would cost $249 for the battery + $50 for the magsafe airline adapter. Personally, I would just replace the battery and go with whatever usage I could get out of it on the flight there and sleep the rest of the time, but for whatever reason she is leaning towards the hyperjuice, and assuming it works as advertised, she could get full usage for the flight out and her husband could use it as well, but that also requires lugging another piece of equipment around and making sure it's charged, etc. If anyone has experience with hyperjuice or other externals or if you've had your battery replaced, I'd love to hear your thoughts on which is the better choice. Thanks!