The first thing I suggest you do is a Battery Calibration
I also use and recommend BatteryCare (free) as suggested above for day to day battery information
To create a log of battery usage I use BatteryInfoView it's free and portable so you can test it and see if it helps you without installing anything.
BatteryInfoView is a small utility for laptops and netbook computers that displays the current status and information about your battery. The displayed battery information includes the battery name, manufacture name, serial number, manufacture date, power state (charging/discharging), current battery capacity, full charged capacity, voltage, charge/discharge rate, and more...
BatteryInfoView also provides a log window, which adds a new log line containing the battery status every 30 seconds or any other time interval that you choose
To save the log file you need to go to
• BatteryInfoView Menu
• Advanced Options
• Tick the box Add battery log lines to the following filename:
The log file will be saved in the BatteryInfoView folder but you can change that if you want