Mobile Mac

Care and Feeding of a Healthy Battery

No rechargeable batteries last forever. In fact, the lithium-ion batteries in today’s iBooks and PowerBooks begin to degrade as soon as they’re shipped from the factory.

Calibrate the Battery New Apple batteries, those included with a machine and those bought separately, arrive partially charged and need to be calibrated. This procedure provides a baseline for the processor built into the battery, so the processor can effectively regulate power consumption. To calibrate your battery, first plug in the laptop and charge the battery to 100 percent capacity; the light at the end of the Apple-supplied power cable will go from orange to green when the battery is fully charged. Next, unplug the power adapter and let the battery run down. The machine will put itself to sleep and refuse to wake up. Plug the adapter in again and fully recharge the battery. (You can use the laptop as you normally would during the calibration process.) You need to calibrate the battery only once.

Work Smart It’s nice to have desktop power on your lap, but do you need to use all that power all the time? When your laptop is running on battery power, use the Energy Saver preference pane to minimize performance and maximize battery life. From the Optimize Energy Settings pop-up menu, choose Longest Battery Life, which puts the hard disk to sleep when possible and reduces the processor’s performance.

Also, use the laptop’s brightness-control keys (usually F1 and F2, depending on the model) to dim the screen’s backlight. And if you don’t need AirPort and Bluetooth, turn them off; even if no other devices are nearby, the wireless radios in the laptop continually scan for networks.

Store the Battery Properly When it’s asleep, a laptop steals power from its battery to maintain the contents of its memory. If you won’t be using the computer for several days, putting it to sleep could drain the battery. Instead, charge the battery to about 40 or 50 percent capacity and shut the computer down. If you need to store a battery for six months or more, remove it from the machine and keep it in a place that won’t get too hot or too cold (between 50 and 90 degrees Fahrenheit).

Stay in Charge

How you charge the battery is just as important as how you discharge it. Current iBooks and PowerBooks ship with a 65-watt AC adapter that powers the machine and recharges the battery. If you’ve moved up from an iBook (dual USB) or a Titanium PowerBook G4, you can use the older machine’s 45-watt adapter as an extra charger for the new Macs, but Apple doesn’t recommend it: that wattage is enough to keep you working but not enough to charge the battery at the same time.

Of course, you don’t have to use Apple’s chargers. The iAdapter2, sold by Lind Electronics ($70), is lighter and more compact than Apple’s little white bricks. Madsonline sells the diminutive, 45-watt MicroAdapter ($78) for previous-generation iBooks and PowerBooks. Kensington’s Universal Laptop Power Supply ($120) can deliver 90 watts of power and is smart enough to judge how much wattage your laptop can safely handle. It includes a car adapter for charging on the road, and it features several plug tips that allow the power supply to work with other laptop models.

Don’t Use Just the AC Adapter If you always plug your laptop into the wall while you work, the battery doesn’t discharge; its electrons stagnate, and the battery’s life span is reduced. Even if you usually use an AC adapter, make a point of working from the battery once a month and then recharging.

Recharge Smart Nickel-cadmium batteries suffered from the “memory effect”—if you didn’t fully discharge a nickel-cadmium battery occasionally, some of its capacity would become unusable until you ran the battery to zero and charged it up again. Although lithium-ion batteries don’t suffer from the memory effect, they do need to have their electrons jostled occasionally to prevent premature decay. Try to complete a full charge-and-discharge cycle at least once per month. According to Apple, a lithium-ion battery should retain 80 percent of its original capacity after 300 full charge-and-discharge cycles.

Is It Time for a New Battery?

At some point, even smart power management can’t overcome the physics of an aging battery. When testing batteries for this article, I found a great example of battery neglect: an iBook that I’d been using as a music server had remained plugged in at the same location for a couple of years. Its lithium-ion battery registered an embarrassing 1 hour and 21 minutes of life with the Energy Saver options set to Longest Battery Life. A replacement battery from BTI ( clocked in with a more respectable 3 hours and 57 minutes (see “Stamina Testing”).

It’s useful to measure your battery’s capacity over time. To determine a battery’s capacity, use a utility such as Jeremy Kezer’s XBattery ($15; or Rayner Software’s iBatt ($15; iBatt compares your battery’s capacity with a median of other iBatt users’ batteries, and it helps determine whether you need a replacement. If the battery provides less than 50 percent of its original capacity and you’re still covered by the laptop’s one-year warranty (or Apple Care’s three-year warranty), Apple will replace the battery at no cost.

If you’re using a much older model, such as a PowerBook 1400cs, your only option is to turn to a third-party battery vendor such as BTI or Lind Electronics since Apple no longer sells batteries for older models. Nearly all battery and computer vendors sell replacement batteries for current models. To be competitive, some companies offer higher-capacity batteries that benefit from improvements in battery technology since the original models were introduced.

For more backup battery power, look into buying an external battery such as the Valence N-Charge ($300;—when fully powered, it acts as a self-contained AC adapter that keeps your internal battery charged for up to ten hours. (But remember, that’s the manufacturer’s best-case scenario.) For some frequent travelers, this type of device my be preferable to juggling multiple battery packs, though it adds about three pounds to your bag.

And remember that when you buy a new battery, you must get rid of the old battery properly. Organizations such as the Rechargeable Battery Recycling Corporation ( ensure that the batteries’ dangerous components are safely recycled and disposed of.

Power On

Taking care of your laptop isn’t too difficult: don’t drop it, throw it, submerge it, or set it on fire. Taking care of the battery is a bit more complicated. But by managing your power—calibrating the battery when you first get it, charging and discharging it to prevent premature decay, and extending your portable capabilities with extra batteries and chargers—you can get much more out of your iBook or PowerBook.

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