Rejuvenate a Lithium-Ion Laptop Battery

Lithium-ion batteries are found in many common portable electronic devices. Thanks to their small size, lightness and power output, they have quickly become the industry standard for use in cell phones, PDAs and laptops. Unfortunately, there are a few drawbacks to lithium-ion technology that can cause its capacity to be greatly reduced. If your battery isn't holding a charge like it used to, there are things you can do to extend your battery's life.

1. Charge your battery every day, if possible, and don't let the charge reach zero. Your battery should reach 80 percent charge in an hour or two (depending on its size), but the last 20 percent may take a bit longer. For best results, keep your battery at 100 percent as much as possible.

2. Avoid heat and store unused batteries in a cool place. If you won't be using the battery for a long time, charge it to 50 percent, remove it from the device and store it in the refrigerator. The cooler temperature will prolong its life. Conversely, don't expose lithium-ion batteries to extended periods of heat. High heat degrades battery life much more quickly, so leaving your iPod or laptop in a hot car on a sunny day will accelerate its aging process.

3. Only buy batteries when needed. Lithium-ion batteries "age" from the time they're manufactured and lose capacity slowly and predictably. For example, a brand-new, unused battery drains slowly because of increased internal resistance and its built-in voltage monitoring circuit. A well-ventilated laptop battery, kept at 100 percent charge most of the time, will irreversibly lose about 20 percent capacity per year.

4. "Deep cycle" your battery every 30 days. Let your device drain the battery until it turns off, then charge the battery to 100 percent. This recalibrates the internal circuitry that detects how much charge is left, giving you more accurate battery readings.