Notebook computers are amazing in some ways, but troublesome in others. On the plus side, they’re portable, they’re stylish, and they’re sexy. But on the downside, they offer much less "bang for your buck" than the average desktop computer, typically providing the user with less disk space, less memory, and above all, less processing power than an comparably- priced desktop. Getting the most from your MacBook or MacBook Pro is as much about mitigating those shortcomings, as it is building upon their virtues.
Power to the People
Modern lithium-ion (Li-Ion) battery technology provides a good balance between power and weight, but they don’t last forever. At $130 a pop, the system battery in your MacBook or MacBook Pro is an expensive item to replace. Apple figures that the batteries supplied with its notebook computers should retain about 80% of their capacity after 300 charging cycles. One cycle occurs when a fully charged battery is completely discharged and then recharged again. Obviously the more often you use your notebook computer away from an outlet, the more rapidly you’ll chug through those precious battery cycles, and the sooner you’ll have to come up with the cash for a new battery. To determine exactly how many times your battery has been cycled, take a look at the ’Power’ section of the System Profiler (choose About This Mac from the Apple menu, and then click on the More Info button).
Even if you don’t regularly discharge the battery and opt to plug in your notebook, the battery will still lose a little of its capacity over time. This slow decay is inevitable and there’s nothing you can do to prevent it. But certain things exacerbate the rate at which Li-Ion batteries degrade, and by avoiding those things, you can extend the useful life of the battery.