Unplug a PC laptop that states up to 4 hours battery life, and let me know if you manage to get more than 1.5 hours out of it. 
I guess it depends on what you're doing unplugged. The obvious things: dim the display, turn off the keyboard back lighting. Set it up for longer battery life. Try single tasking to reduce memory and CPU usage. (don't forget to cmd+q out of apps.)
If all else fails, pick up one of those nifty solar panel laptop bags.
I guess it depends on what you're doing unplugged. The obvious things: dim the display, turn off the keyboard back lighting. Set it up for longer battery life. Try single tasking to reduce memory and CPU usage. (don't forget to cmd+q out of apps.)
If all else fails, pick up one of those nifty solar panel laptop bags.