MacBook users have started to discover over the last few years that their batteries can take a total nosedive into uselessness in just a few months. The first battery on my 2008 MacBook Pro was dead by the end of 2009, flat dead, and out of warranty too. Damn. Cause of death? Lack of "battery conditioning" also known as "calibration".
If you want to know how to calibrate your battery, you can refer to this hard to find guide from Apple:
To calibrate the battery:
- Plug in the MagSafe power adapter and fully charge the MacBook or MacBook Pro battery until the light on the MagSafe connector changes to green and the Battery icon in the menu bar indicates that the battery is fully charged.
- Allow the battery to rest in the fully charged state for two hours or longer. You may use your computer during this time as long as the power adapter is plugged in.
- Disconnect the power adapter with the computer on and start using it with battery power. When the battery's charge gets low, you’ll see the low battery warning dialog on the screen.
- Continue to keep your computer turned on until it goes to sleep. Save your work and close all applications when the battery's charge gets low and before the computer goes to sleep.
- Turn off the computer or allow it to sleep for five hours or longer.
- Reconnect the power adapter and leave it connected until the battery is fully charged. You may use your computer during this time.
Pretty easy to understand, right? Yeah, the only problem is that even though you're supposed to this every month or two, there's no facility on the mac that actually, you know, prompts you to do it. Nothing, nada, zap diddly doo. You'd think that Apple with their vaunted usability standards would pop up a message at the right time saying "hey, now would be a good time to condition the old battery, here's how to do it".
Also, Apple's instructions are missing two other key pieces of information. The first is that you should immediately download a wonderful app called Coconut Battery. Go ahead, I'll wait. It will tell you how crap your battery is and you can save the data to get a history over time.
Second is that that condition is not something you can overdo. Don't just do it once. Do it twice, three times even. Keep doing it until you stop seeing capacity gains in coconut battery. Most recently, my first condition went from 71% to 76%, and the second brought me up to 80%. I'm going to see how high I can get.
All in all this is a bit of a failure on Apple's part, and it makes you wonder if perhaps they are making a load of money from selling replacement batteries. It doesn't seem in character for the company. More likely, they just haven't put the time into designing a proper monitoring system that detects when you need to condition. Hopefully we'll get that soon.