BattStat

"BattStat" is a systray application which uses the smart battery support in Windows 7, Vista, XP and 2000 to monitor power usage, battery charge, CPU speed, CPU usage, and power events such as standby/hibernate/resume, battery events, etc. Additionally, its capable of monitoring CPU temperature (via Intel Core internal sensors, or ACPI thermal sensors), hard drive temperature (if the drive supports it), and even control traditional hard drive APM/AAM/spindown settings, like the Hitachi PowerBooster does. The binary is about 320KB and though it comes with an installer, it requires no special installation, dlls, etc. It can be autorun from the registry with a checkbox. It can run with or without administrator privileges, though certain functions will be disabled without it.

The systray icon resembles PowerPanel rather strongly, but integrates battery capacity, AC power status, and CPU speed in a single icon. It has a graphical display window that can be popped up on-demand, which graphs up to 8 parameters over a several hour period, and shows instantaneous status in a window (which is also available in a systray tooltip). It estimates runtime when discharging, and charge time when charging. It displays instantaneous and long-term average power usage.

In addition to the systray and main window graph, it has a toolbar-style window that can float anywhere on the screen which compactly integrates the systray icon, a charge meter and summary of runtime.

It has a programmable hotkey to turn off the screen, which can be used to save significant power when running on battery if you need to turn away for a short time, its also nice as a "privacy key" if you need to blank your screen instantly. The program can run a program or batch file any time the system switches power source, or resumes from standby or hibernation, something I find useful to perform certain checks automatically to recover state that many programs blissfully ignore.

Theres a detailed battery display for up to two batteries, with names, voltages, temperature, design capacities, wear percentages, etc, as provided by the batteries themselves.

Finally, it can switch Win7/Vista power plans and XP/2000 power schemes with a single click, as well as standby and hibernate the system.