iBatt for Mac

From Rayner Software:

iBatt is the most full-featured PowerBook battery monitor and diagnostic tool available for the Mac.

iBatt digs deep into the system to get every bit of available battery data. The OS only reports your charge level, but iBatt reports total capacity as well as voltage. This lets you know how worn out your battery is, and whether or not it's time to replace it. Battery data can be viewed in either graph or numerical format. The graphing window provides a flexible data view, allowing you to view trends over the course of 10 minutes, up to one month. The statistical view shows you all the current numbers for your battery. It covers Capacity, Charge, Voltage, and State.

But what good is all this data without a frame of reference? Following Rayner Software's tradition for network-enabled programs, iBatt is completely Internet aware. You have the option to report your battery statistics to iBatt's server for use as a benchmark. But even if you opt out of this, you can still view your battery's stats in comparison with averages collected from PowerBooks around the world. This will let you know how your battery performs in relation to the average battery in your model of PowerBook. iBatt also provides a plain-english report and a letter grade to give you an easy-to-read battery report card. The registered version of iBatt allows you to check out stats on other PowerBook models.