A battery allows a portable computer to operate without an AC power source, thereby making it portable in the true sense. (Otherwise, you would need very long extension cords.)

Portable computers include power management functions (either built-in or through special device drivers). These functions make the portable PC “go to sleep” when there has been no input from the keyboard for a preset time period. The computer runs, but power drawing features like the screen are suspended until you “wake” your PC by pressing a key. When the PC is sleeping, the battery isn’t being used, thus preserving the life of the battery.

A portable computer has two battery types:

I. Main battery. Powers the computer while it runs. Also powers the RTC chip when the computer is switched off. There are four main battery types:

1. • Alkaline. Normally used in palmtop computers. These are the batteries that you use in calculators and TV remote controls.
2. • NiCad (Nickel-Cadmium). Common batteries in portable computers. These are the heaviest, least expensive batteries. They need to be recharged after 3 or 4 hours of use.
3. • Li-Ion (Lithium-Ion). Light, long-lasting alternative to NiCad batteries. They’re very expensive.
4. • NiMH (Nickel-Metal Hydride). Environmentally-friendly batteries that don’t contain toxic metals. The same weight as NiCad batteries, but more expensive and can’t be reused as many times.

II. CMOS battery. Saves the computer’s BIOS setup configuration, allowing the computer to successfully reboot every time. When the computer is switched off, this battery maintains the computer’s date and time.

Handling batteries

Batteries contain toxic chemicals. If not properly handled, they can explode, harming you and your computer. Follow these guidelines:

• 1. Keep batteries away from fire and water.
• 2. Never open or dismantle batteries.
• 3. Don’t drop or throw batteries.
• 4. Follow the manufacturer’s guidelines.

Maximizing battery performance

To maximize portable computer battery performance, follow these guidelines:

• 1. Fully charge and discharge a new battery, or a battery that has not been in use for a long time. A battery is generally discharged to increase its longevity. To discharge a battery, plug in your portable computer and leave it on overnight or longer, if necessary. Once the battery is discharged, the computer will shut down. You can then recharge the battery using the AC adapter. You should charge and discharge a new battery, or a battery that hasn’t been used for a long time, approximately two to four times to maximize its performance.
• 2. Regularly charge and discharge batteries completely every two to three weeks, to keep them healthy. (You need not do this for a Li-Ion battery.)
• 3. Keep batteries clean. This helps maintain a good connection between the battery and the portable device.
• 4. Don’t leave batteries dormant for long periods of time.
• 5. Store batteries in a cool, dry, clean place away from heat and other metallic objects if you aren’t planning to use it for a long time.
• 6. Don’t connect the PC to the AC adapter all the time. This wears the batteries faster than usual.
• 7. Don’t operate the PC while its battery is recharging.
• 8. Switch off the PC when you aren’t planning to use it for a while, even if it has sleep mode.

Changing batteries

Your computer generates the message “Invalid Configuration. Run Setup or press F1 to continue.” But when you press F1, you get another message, “Invalid Drive Specification,” and your computer stops functioning. It’s time to change the computer’s battery. To change the battery:

1. Record the current CMOS settings. To do this, turn on (or restart) the computer and display the CMOS settings. You can either jot down the settings or press the Print Screen key to print the displayed settings. You may need this information if you lose your computer’s current settings.

2. Turn off the computer.

3. If the computer is connected to the AC adapter, unplug it.

4. Disconnect such peripheral components as printers, modems, and networks.

5. Remove the existing battery.

The existing battery may be

1. • In the holder at the bottom of the computer. (If so, the hatch slides out easily.)
2. • Attached to the computer (in which case you may need to unscrew it, release a lock, or lift the keyboard).

6. Replace the old battery with the new one that you’ve purchased. Make sure that the battery is replaced in exactly the same configuration and polarity (+ and – settings). If in doubt, check the documentation. After you have opened your computer, replace the battery immediately. If you delay, the battery or the computer may be damaged.

7. Close the computer and plug in the AC adapter.

8. Start the computer. Reset the computer date and time, if necessary.