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Power to the people: ZDNet's guide to notebook batteries

Brian Nadel CNET

Published: 14 Apr 2004

Ten tips for the power-hungry

With a little power conservation and some smart moves, you can greatly improve your notebook's battery life. Here are our top 10 tips for getting the most out of your batteries.

1. Think small

If extra-long battery life matters to you, forget about that huge, 17in.-screen notebook with the top-speed processor -- it probably won't run for more than two hours. When you're buying your next notebook, think small and consider an ultra-portable or a thin-and-light system. An Intel Pentium M processor uses about half as much power as a Pentium 4, a 12.1in. screen uses 50 percent less juice than a 17in. model, and getting a 4,200rpm hard drive instead of a 5,400rpm model can mean an extra 15 to 20 minutes of battery life.

2. Control your power

Adjust your notebook's power settings to find a comfort zone where you're using as little power as possible with no interference in your computing tasks. The path to the control panel will vary according to your operating system and setup, but for Windows XP Home and Pro users, follow these steps: Go to Start / Control Panel / Performance And Maintenance / Power Options. Set the LCD screen to go off after 5 minutes of inactivity, let the hard drive stay active for 20 minutes, and store the system's contents in RAM when it shuts down. If your notebook goes to sleep too soon, adjust the settings.

Adjusting power and other options in the Power Options Properties dialogue will improve your battery life.

3. Dim all the lights

Your LCD's backlight uses up to 10 watts of power, a huge battery drain. Lower the screen's brightness to where it's comfortable to view without squinting. In addition to the Power Options settings detailed above, most notebooks have convenient function keys for controlling screen brightness. Look for the function key with the brightness icon and a down arrow next to it (this is the F6 key on many systems). Also, some new notebooks, such as Apple's 17in. PowerBook, adjust the screen's brightness to suit the conditions.

4. Be battery smart

Know how much power remains by checking the battery power icon in the system tray. Or buy a notebook with a battery that features a charge-level LED gauge on the battery itself so that you can just flip over the system to see how much battery life remains. If you really want to see tons of detail on what your battery is doing and how much life is left, take battery monitoring to the next level with PassMark's BatteryMon utility.

5. Double or triple your pleasure

Some notebooks, such as Fujitsu's LifeBook S series, let you double up with a second battery that fits into a modular bay, nearly doubling runtime. A few systems can even take as many as three batteries, if you include the docking station, also called a media slice. The IBM ThinkPad X40, for instance, can be fitted with a large-capacity battery in place of its standard battery, and it has a connector for an additional bottom-mounted external battery.

6. Charge when you can

Before leaving the home or the office with your notebook, fully charge all of your batteries. If you're travelling, look around for a wall outlet to give your batteries a refresher charge when you can, because every little bit helps. Some third-party devices will help you charge on the road, such as iGo's Juice 70 ($120 / ~£66). This versatile device does it all: it's a regular AC adapter, as well as a car converter, and it will work on many airplanes. With the right plug, it can even charge your phone or handheld.

7. Check the CMOS battery

If you have to reset your notebook's clock or your system BIOS, you may have a bad backup battery. Also called the CMOS battery, this secondary battery, which powers the clock when the system is not in use, can sap the main battery power if it's dead. The good news is that this battery is inexpensive. The bad news is that you'll likely have to dig around inside the system to find it. Some vendors put the backup battery under the memory chip slots, while others stash the CMOS battery under or next to the main battery. Check your manual or the vendor's technical support Web site for details.

8. Shut down unnecessary programs

When you're running your notebook on battery power, turn off devices and programs you don't need. When not connected to a wireless hot spot, turn off the Wi-Fi hardware. If you access wireless networks with a PC Card, remove it when not connected. Listening to music via the CD-ROM drive and watching DVDs are also big battery drains.

9. Start with complete battery drains

To ensure long-term battery vitality, do the following: when first using your notebook on battery power, let the battery completely drain before you recharge it. Don't recharge when the battery is only half drained. Do that for at least the first two sessions. Also, avoid temperature extremes. Don't leave a notebook in a hot car or use it outdoors in extremely cold weather; hot batteries discharge very quickly, and cold ones can't create as much power.

10. Terminal care

Make sure the battery contacts that connect your cells to the notebook are straight and clean and free of grime, because the last thing you need is a bad connection. Most contacts are flat, copper-coloured metal strips, but they might be hidden between pieces of protective plastic. Every six months or so, give the contacts a cleaning with a cotton swab and rubbing alcohol to remove electron-sapping dirt and grime. A bad connection can keep you from getting the most out of a battery.