Although laptop batteries don't suffer from the "memory effect" of other types of rechargeable batteries, the battery power meter can become out of sync with the actual amount of power stored. This is most likely to happen when you run your laptop off the battery for a short amount of time and then recharge it. Resetting your battery recalibrates the Dell battery power meter to prevent inaccurate low-power messages and can be done once every three to six months.
Disconnect the AC power adaptor by unplugging it from the laptop or docking station.
Restart your laptop. When you see the large Dell logo on the screen, press the "F2" key to enter the BIOS set-up screen. Press the "Alt" and "P" keys together to page through the BIOS settings until you reach the screen that includes the Power Management settings, on page four or five.
Navigate to the Power Management settings with the "Up Arrow" and "Down Arrow" keys. Under both the "Battery" and "AC" columns, use the "Left Arrow" and "Right Arrow" keys to set Power Management to "Disabled."
Press the "Esc" key to exit the BIOS settings and save your changes. Allow the laptop to complete the restart process and then leave it switched on without the AC adaptor plugged in, until the battery is completely discharged and the laptop switches itself off.
Plug in the AC adaptor and recharge the battery without switching on the laptop. Allow the battery to fully charge, which will take up to two hours.
Repeat Steps 2 and 3 but set your Power Management setting to "Enabled." Press the "Esc" key to exit and save your BIOS settings and allow your laptop to complete its restart.
For longer battery life in hot climates, run your battery down to 40 per cent charged, remove it from your laptop and store the battery in a sealed plastic bag in your refrigerator until you need it.