There's a lot going on under the hood of Snow Leopard, to be sure, but a subtle change has been made to the battery menu item that will help portable users diagnose failing batteries.
Within the new Battery menu bar extra in Mac OS X v10.6, you may see one of these messages:
- Replace Soon
- Replace Now
- Check Battery
According to a new Apple knowledgebase article "Replace Soon" means that the battery may still be usable and hold some charge, but you'll need to consider getting the battery replaced. If the battery is removable, Apple recommends removing and reseating it with the power cord connected and plugged into a power outlet.
If the battery is not removable Apple recommends resetting the System Management Controller (SMC) as outlined in this knowledgebase article. If "Replace Soon" continues to appear after reseating the battery or resetting the SMC you'll need to replace the battery or take the computer to an Apple Authorized Service Provider.
The Battery menu will display either a "Replace Now" or "Check Battery" alert if it is unable to hold a charge for long (or at all). If you see one of these alerts, and if the battery is removable, Apple recommends that you try removing and reseating it with the power cord connected to your computer and a power outlet. If the battery is not removable try resetting the System Management Controller (SMC). If the issue persists your battery may need to be inspected and/or replaced.
Apple notes on its battery page that it's important to exercise your machine's battery (as I reported back in July) and that Lithium-ion polymer batteries need to be used for properly to achieve maximum performance. Apple recommends that if you don’t use your device often, you should complete a charge cycle at least once a month.
A charge cycle means using all of the battery’s power, but that doesn’t necessarily mean a single charge. For instance, you could listen to your iPod for a few hours one day, using half its power, and then recharge it fully. If you did the same thing the next day, it would count as one charge cycle, not two, so you may take several days to complete a cycle. Each time you complete a charge cycle, it diminishes battery capacity slightly, but you can put notebook, iPod, and iPhone batteries through many charge cycles before they will only hold 80% of original battery capacity.