So some things you obviously have to do to extend unplugged battery life:
- Turn off the Airport Extreme WiFi card
- Turn off Bluetooth
- Change your Energy Savings setting to Better Battery Performance
- Turn down the brightness on you LCD
One of the things I hadn't really considered necessary, and in fact their is no way to do this in OS X without at least some of the Xcode Developer Tools installed, is disabling the 2nd core on the Core Duo. Tom Yager for Enterprise Mac wrote about this back in March, but I hadn't thought about doing this until this morning. Wow. The same experience with the battery meter Tom saw back in March, I see now even post an OS X update (10.4.8 came out in September) and a MacBook Pro firmware update. This is actually great news, because after a 50 minute EVDO connection with 1 core running, I still have 1:20 of battery life left. The night ride home, I have ~20-30 minutes left. When you have the Developer Tools installed, you get a new System Preference, Processor, that gives you control over your CPUs (core or physical).
When you click on this System Preference, you see you can enable or disable the 2-n cores, and also add processor control as a menu item, great!
One core enabled
Two cores enabled