Check your battery’s health with System Profiler
A new Mac laptop, such as a MacBook Pro or a MacBook, can run for maybe 3 or 4 hours on battery. After a while though that fully charged battery will last for only 2 hours, then 1, until eventually it just dies.
Mac Tip #354, 03 September 2008
That’s the way of all rechargeable batteries — they have a certain number of ‘cycles’ in them. As the months go by the battery’s capacity gradually declines.
Back in Battery check, Mac Tip #260/13-Sept-2006, I explained how to use the button on the battery itself to check the charge. System Profiler gives you more detailed information: the number of charging cycles, the make of the battery, the capacity and so on.
Open up Applications > Utilities > System Profiler. A window appears showing information about your Mac.
Click on Power, under Hardware in the list of Contents on the left of the System Profiler window. Battery and other Power Settings information is displayed in the right-hand pane.
The Model Information section shows the battery’s serial number, manufacturer and other data about its manufacture.
The Charge Information and Health Information sections are the ones to monitor.
A charge cycle is when the battery is run flat and then recharged to full. If you run the battery partly down and recharge it, that counts as part of one cycle.
The battery’s capacity to store a charge is measure in Milliamps Per Hour (mAh).
Click the screenshots for larger versions.
In the first screenshot I can see that my brand new battery has been discharged and recharged 3 times (Cycle count: 3). It’s fully charged and has 5417 mAh capacity remaining. Its Full charge capacity is 5454 mAh. The Condition of the battery is listed as:
Good, under Health Information.
The 3rd party battery (ie, not from Apple) in the second screenshot has been discharged and recharged 49 times (Cycle count: 49). It’s fully charged but has only 1673 mAh capacity remaining. Its Full charge capacity is only 1680 mAh. The Condition of the battery is listed as:
Check battery, under Health Information.
This battery seems to have a problem. It hasn’t been used very much but its capacity is very low. I suspect a problem with it and have contacted the supplier for support.
If you use a Mac laptop, take a look at System Profiler to give it a health check.
Update: I’m using Mac OS X 10.5.4, Leopard. Older versions of the Operating System may have less Power information, or maybe none at all.
In Lion you now find this data in the System Information app.
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