Calibrate Laptop Battery

It’s time for that important presentation. You open your laptop which is in Sleep Mode only to find that the laptop battery that lasted for 6 to 7 hours when you bought it now survives only for an hour or more. You have no choice but to run for finding an external power source.

Today, all portable computers use Lithium Ion batteries instead of the old style Nickel Cadmium ones. Advantage – these batteries are able to hold a greater charge as well as they are light weight – very important factors for laptops. Batteries come in different variations like 6-Cell, 9-Cell, 12-Cell, etc. Each cell has a defined capacity to store the charge and also each battery (comprising of these cells) has a limited number of charge cycles. A charge cycle is nothing but a full charge to discharge and then a full charge cycle. Since each battery pack has limited charge cycles, over a period of time, the battery wears out thus giving less battery time.

All laptop users face this problem. I did too on my HP DV6 as I saw the battery drain out in less then an hour after a full charge. The next thought in my mind was to get the battery replaced by a new buy which would cost $$$. But then my geeky mind cranked up and I decided to give Battery Calibration a try.

PC batteries expose information about battery capacity and health through the system firmware (or BIOS). The firmware provides information on the battery including manufacturer, serial number, design capacity and last full charge capacity. This allows the Operating System to know the exact amount of energy stored. However, due to the charging and discharging cycles, this sensor tends to be inaccurate overtime. An inaccurate gauge can lead to the fact that the the battery capacity values are wrong. So, how do we correct this? Perform a battery calibration. Before proceding to the steps, I recommend downloading a utility like Battery Care (http://www.batterycare.net) and installing the same. After installation, note down the wear level, the battery time, etc. This would help for comparing the results after calibration.

NOTE: Even if a battery pack is heavily used, it should not be necessary to calibrate it more than once a month. It is not necessary to calibrate a new laptop battery pack before first use. Calibrate only when you see that the battery is reporting the right capacity and you need to reset the guage.

Follow these steps to calibrate the battery

• Step 1: Fully charge the battery to its maximum capacity, i.e. 100% level
• Step 2: Let the battery “rest” fully charged for 2 hours or more in order to cool down from the charging process. You may use the computer normally within this period
• Step 3: Unplug the power cord and set the computer to hibernate automatically at the minimum percentage possible. You can change this in your Power Plan options under the advanced settings option. Look for the “Battery” option and set the Critical Battery settings.
• Step 4: Leave the computer discharging non-stop until it hibernates itself. You may use the computer normally within this period
• Step 5: When the computer shuts down completely, let it stay in the hibernation state for 5 hours or even more
• Step 6: Plug the computer to external power to perform a full charge non-stop until its maximum capacity (100%). You may use the computer normally within this period.

When I started with the calibration of my laptop battery, the wear level reported was 52.00% and the laptop used to shutdown even when the battery icon showed 30% of charge left. After running the calibration, the wear level reported is 37% and I’m not getting unexpected shutdowns anymore.