Service Battery indicator in Mac OS X
Ever since Mac OS X 10.6, if you have a portable Mac the battery menu will report to you the condition of your battery. There’s two messages you don’t really want to see though, and they are “Replace Now” and “Service Battery”. Basically if a battery is unable to hold a charge, you’ll get one of these messages in your battery status indicator menu.
I’ve personally never seen “Replace Now” but on multiple machines I have encountered the “Service Battery” alert and in almost every case the battery needed to be replaced with a new one. In one odd circumstance though, the battery still worked fine but Mac OS X was reporting the error message anyway, the message was cleared and everything went back to normal after the SMC power management controller was reset. Anytime your Mac has power management type issues it’s worth giving the SMC reset a shot, it might fix the problem.
If you tried the SMC reset to no avail and you think your battery is toast or it’s just being problematic, give Apple a call or stop into an Apple Store. This is particularly helpful if the machine is reporting the “Service Battery” message, if the battery is in warranty they will replace it free of charge. There are even some situations where they will replace out of warranty batteries too, but it’s a case-by-case basis and often relating to the cycle count and age of the battery. You can check your batteries functionality with a free utility called CoconutBattery.