Watts sits in your menu bar, providing an improved alternative to Apple’s stock battery menu item. Like SlimBatteryMonitor (), you can customize Watts’ menu-bar display so that it takes up less room than Apple’s version: you can choose to show just a battery icon (which changes to an AC plug when your laptop is connected to its AC adapter), just the time remaining, or just the percentage charge remaining.
Like Gems favorite Unplugged (), Watts uses Growl to notify you whenever your laptop switches to battery power—useful for those times when your MagSafe connector accidentally gets disconnected—or from battery to AC power. Watts can also notify you, like Unplugged and HardwareGrowler, when your laptop’s remaining charge dips below the percentage you choose.
And like older Gem coconutBattery (and several similar utilities out there), Watts can provide detailed information about the status of your MacBook’s battery. Choose Calibration & More from Watts’ menu and then click the Information button, and Watts displays the number of complete charge cycles you’ve performed on your battery (along with the number of cycles the battery was designed to handle), and the original and current capacity of your battery. A click on the Help button displays explanatory text about each bit of information, and clicking Show Table displays a history of your battery’s capacity—you can manually add the current data to the table.
These features alone would make Watts a useful add-on for MacBook users, but it’s the program’s battery-calibration component that makes it truly unique. Once you’ve set your maintenance schedule—the default is every five weeks, but you can choose to perform the procedure more or less frequently—Watts reminds you when its time to calibrate. (It also offers a Postpone button if you want to put off the procedure for a day or so.)
The utility then walks you through the appropriate steps, telling you, for each step, approximately how much time is remaining:
Plug in the computer and fully charge the battery.
Keep the laptop plugged in, with a fully charged battery, for at least two hours.
Unplug your MacBook’s AC adapter so the computer is running off its battery.
Continue to use the computer until it goes to sleep. (Watts helpfully reminds you, just before sleep, to save any unsaved work.)
Allow the laptop to sleep—unplugged from the AC adapter—for at least five hours.
Reconnect the AC adapter and fully charge the battery.
You can use your laptop during all but Step 5. In fact, you’re encouraged to do so, so you’ll see Watts’ notifications. (Though I wish your progress was displayed in Watts’ menu so you could close the Calibration window during the procedure.)
Watts also has a couple other battery-extending features. Since it’s not good for your MacBook’s battery if you regularly use your laptop while connected to AC power, Watts can remind you to unplug your MacBook after it’s been on and connected to AC power for longer than a period of time you choose. (The default setting is 30 hours.)
At the other extreme, if you won’t be using your MacBook for a while—or if you have an older Apple laptop that lets you swap batteries and you won’t be using one of those batteries for a while—Watts includes a feature for getting the battery to the ideal charge state for storage. Battery vendors recommend against storing a battery for extended periods with a low charge (to avoid the risk that the battery will die completely), and Apple recommends a storage-charge level of 50 percent, rather than full. If you’re getting ready to store your MacBook or battery, Watts will notify you when the battery reaches a 50-percent charge.
Of course, you could get all this battery information from a combination of free utilities, and you could set up an iCal reminder to follow Apple’s battery-calibration routine every month or so. But there’s something to be said for having all these features in one nifty utility that also walks you through the calibration process when the time rolls around.