Both total charging capacity and life of a laptop computer’s battery will diminish as you use your computer. To determine your laptop’s current battery capacity and compare it with what it was when you purchased the laptop, install either of the following applications on your computer.
Microsoft Windows users
Battery Eater – This utility performs a stress test on the battery, causing it to drain to 0. After the battery has been drained, running the utility again provides you a full report that compares the estimated capacity of the battery to its current capacity.
Tip: If you plan on using the Battery Eater test, make sure to disable all power-saving features first.
Apple Macintosh users
Coconut battery – If you are using a MacBook, MacBook Pro, MacBook Air with macOS X 10.5 or higher, Coconut is an easy-to-use utility to test your laptop’s battery.