Laptop Battery Care

Calibrating Your Laptop's Battery

You should calibrate your laptop computer's lithium ion battery for best performance.

The battery has an internal microprocessor that provides an estimate of the amount of energy in the battery as it charges and discharges. The battery needs to be recalibrated from time to time to keep the onscreen battery time and percent display accurate. With all laptops, you should perform this procedure when you first use your computer and then every few months thereafter.

  1. Plug the power adapter in and fully charge your computer's battery until the battery indicator lights turn off and the adapter plug ring goes from amber to green, which indicates that the battery is fully charged.
  2. Disconnect the power adapter and use your laptop or PowerBook. When your battery gets low, you will see the low battery warning dialog on the screen. Continue to use your computer until it goes to sleep. At that point the battery has been sufficiently drained for calibration.
  3. Connect the power adapter and leave it connected until the battery is fully charged again.

You have to fully charge and then discharge your battery only once to calibrate it. After that, you can connect and disconnect the power adapter when the battery is at any charge level.

Tip: When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, any open files could be lost. Therefore, it is important that you find an electrical outlet and connect the adapter before the forced shutdown occurs.

Storing Your Laptop's Battery

  • 1 to 2 months - Battery should still have minimal charge to operate the computer.
  • 6 to 12 months - Battery can still be charged.
  • 12 months or more - Uncertain.

Batteries may be damaged if stored for prolonged periods with a closed circuit. The environmental temperature also affects the storage life of any battery. Cool environments are best, and are assumed for the above estimates. All storage times are based on storage starting with the battery fully charged.

For example, schools that may not use their laptop or PowerBook computers during the summer should fully charge the batteries, remove them from the computers, and store them in a cool location for the duration of the summer.