I usually work as a root in terminal without running x window system. This tool help me to check my laptop battery power statistics. Whereas in X window system (GNOME) you can easily check battery status in panel or by typing gnome-power-statistics command in terminal.

Install the ACPI tool first.
apt-get install acpi
Use the acpi command to display the status of your laptop battery
This command also has many other options. This one shows the CPU temperature.
acpi -t
And this one shows the status of the cooling in your machine.
acpi -c
For all information together type
acpi -V
and for help just type acpi --help

Hope it will increase you knowledge and please don't tell me about any other tools names as i know there are dozens of tools as well for this purpose like powertop but i like this its simple and accurate thanks.