Check your battery’s health with System Profiler

Check your battery’s health with System Profiler
Mac Tip #354, 03 September 2008

Black MacBook - open

Black MacBook - open

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.

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.

Brand new Apple battery - information.

Brand new Apple battery - information.

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.

Possibly faulty 3rd party battery - information.

Possibly faulty 3rd party battery - 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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  1. Steven said:

    The statement “The battery’s capacity to store a charge is measure in Milliamps Per Hour (mAh).” is incorrect. The battery capacity is measured in milliamps times hours, not milliamps divided by hours.

    A fully-charged battery rated for 100 mAh can power a 100 mA load for one hour, or a 50 mA load for 2 hours, or a 10 mA load for 10 hours.

    100 mA x 1 hour = 100 mAh
    50 mA x 2 hours = 100 mAh
    10 mA x 10 hours = 100 mAh

  2. Alma said:

    I can’t seem to find the “condition” of my battery in my System Profiler.

    I am worried as after 3 hours my battery is low.

    My cycle count is 848 and my Mac age is 56 months. Does this mean I need to replace my battery?

    • Miraz Jordan said:

      The numbers are just a guide. What’s really important is whether or not the battery does what you need it to do.

      3 hours is good. It’s when it gets down to 1 hour or less that I’d consider replacing it.

      I hope that helps.

  3. Bhaity said:

    I’m trying to figure out if I have a problem with my battery or with my charger, but I don’t see “Health Information” under Battery Information. I’m using OS X 10.4.
    My “Remaining Capacity” is at 0 but the cycle count is also at 0.. does this mean it’s totally dead?

    Battery Information:

    Battery Installed: Yes
    First low level warning: No
    Full Charge Capacity (mAh): 3970
    Remaining Capacity (mAh): 0
    Amperage (mA): 0
    Voltage (mV): 2912
    Cycle Count: 0

    AC Charger Information:

    AC Charger (Watts): 65
    Connected: Yes
    Charging: No

    • Miraz Jordan said:

      The lines “Remaining Capacity (mAh): 0″ and “Charging: No” suggest to me the battery is dead, but it may be a charger problem.

      Your IP address suggests to me you may be in a place where you have access to an Apple Store and Genius Bar. I’d suggest you take the machine in to them. At the very least they could probably test whether a different charger will charge your machine and battery.

      If you can borrow a charger or battery you could always try swapping things around.

      I was having problems with my MacBook Pro suddenly turning off recently. A new charger fixed it!

      I hope that helps.



  4. The Cute Penguin said:

    Oh, but my mac is only 2 years old but it is only 88 – 100 mins of battery. Why?

    • Miraz Jordan said:

      Batteries are good for a certain number of cycles. How you use the Mac, how much and how often on battery and many other factors all affect battery life. You could maybe check with Apple to see if they can suggest ways to extend it.

  5. Carolina said:

    i have 905 cycle counts my computer is from 2008 mac 10.4.11…does that mean it will die very soon?

    • Miraz Jordan said:

      Does the System Profiler have a ‘Health information’ line near the cycle count? That should tell you a bit more. What about the maximum capacity?

      At a guess though a cycle count that high suggests you may need a new battery before too long. How long does it last between charges?

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  7. Miraz said:

    Massimo: I’d say you’re doing pretty well on your battery with 1.5 hours for 376 charges.

    My battery has 79 cycles and currently shows around 1.5 hours remaining.

    The amount of time any on full charge gives you depends a whole lot on what you’re doing – eg reading, typing, playing music – and on what services you’re using – eg wireless, backlight and so on.

    Apple suggest you fully discharge the battery around once per month and fully recharge it for best maintenance. There’s no problem with charging it fully.

  8. Paul H. said:

    I have been charging and using my MacBook for about 2 years now. I still get 3 hours or more of battery. One thing though, about 1 year into having it, the battery terminals on the battery side started corroding or something. They gave me a shiny new battery! I have about 350 charge cycles on this one.

  9. Massimo said:

    Also I don’t know whether charging the battery to its full is damaging or not?
    Is it better to charge it up to 70 – 80 % and then use it?

  10. Massimo said:

    My cycle count is 376.. after how many cycles does the battery has to be replaced?

    My battery life lasts about 1.5 hours.. not much !!!

    Need some advice.. I am considering replacing the battery but is quite expensive I believe.. I have tried different settings to increase h the battery life but is not making much difference.. battery still runs out quickly.

  11. Maddy said:

    MY cycle count is 319. Im getting some 1 Hour battery life. Before i had 4 hours of battery life :)

  12. Peter Rankilor said:

    Thanks for this useful explanation.

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