While looking for battery savers, besides JuiceDefender; I came across this great app:
What Is It ?Tasker is an application for Android which performs Tasks (sets of Actions) based on Contexts (application, time, date, location, event, gesture) in user-defined Profiles, or in clickable or timer home screen widgets. This simple concept profoundly extends your control of your Android device and it's capabilities, without the need for 'root' or a special home screen.
Tasker came 3rd in the Productivity category in the Android Developer Challenge 2.
Sounds like it will do your battery monitoring and hundreds
of other useful things too! Looks like this might be
the essential Smart Phone App for Android.
Check out the LifeHacker Post:
How to Turn Your Android Phone into a Fully-Automated Superphone