10 Replies Latest reply: Feb 17, 2010 2:08 PM by Rod Hagen
Bluesygirl Level 3 Level 3
I have a Macbook Pro and noticed lately that it never gives me that "low battery" warning any longer. Rather, it just completely shuts down when it runs out of juice. Oftentimes I am sitting in front of the tv and surfing the web and while I realize it's running low, it'll just shut off. In the past - and I admit I mostly use my Mac plugged in at my desk - I'd always get that warning. Why is that and how can I get the warning back? At least it would give me ample time to get it plugged in before shutdown. Thanks.

Macbook Pro Core Duo 2; Airport Extreme Base Station "n", Mac OS X (10.4.10), Powerbook G4; iPod nano (2nd gen); iPhone 8G
  • Rod Hagen Level 7 Level 7
    How old is the battery, Bluesygirl?

    Once batteries deteriorate to a certain point their behaviour can become unpredictable, and prevent the "warning" from occurring when it should, especially if a particular program suddenly needs a bit more power than usual (like when you access a "Flash" based website, for example.)

    THe solution , in this case, is to simply get a new battery.

    Sometimes , with a newer battery, the problem can also occur because the battery needs to be re-calibrated. See http://support.apple.com/kb/HT1490 for instructions on how to do this.


  • Bluesygirl Level 3 Level 3
    The laptop is around 3-4 years old. Here is the battery info from the profiler:

    Battery Installed: Yes
    First low level warning: No
    Full Charge Capacity (mAh): 5103
    Remaining Capacity (mAh): 3951
    Amperage (mA): 888
    Voltage (mV): 12448
    Cycle Count: 44

    Based on the cycle count it doesn't seem like it should be time for a new battery??
  • Rod Hagen Level 7 Level 7
    The full charge capacity of the battery actually looks pretty good for 3 to 4 years old if this is a 15" MBP, Bluesygirl. (If it is a 17" then it is not so positive)

    The problem with the cycle count is actually that it is way too LOW if the battery is this age. Lithium batteries actually need to be regularly used to maintain their condition. (see http://www.apple.com/batteries/notebooks.html and http://discussions.apple.com/thread.jspa?threadID=1764220 for good advice on maximising battery life). A battery that had been used in a fashion likely to maximise battery life would probably have completed at least 100 to 150 cycles by now at that age.

    The age of the battery (if it is the same as the computer) also counts against it. The "real world" life expectancy of the batteries fitted in the 2006 to 2008 generally seems to be about two to three years.

    Given the comparatively good full charge capacity that System Profiler identifies it is worth doing two things. Firstly you should try to recalibrate it following the instructions in the link in my previous post. THis will give a better idea of whether the battery really does have the capacity claimed. Secondly you should take it to an Apple store or AASP to get tested. Sometimes even though batteries maintain a fairly high voltage level / total capacity they lose the ability to meet sudden high current demand situations.

    You might also consider resetting your SMC ( see http://support.apple.com/kb/HT3964 ), but I think it would be wise to do the calibration and get the battery tested first, given the symptoms you describe.


  • Bluesygirl Level 3 Level 3
    Thanks for all the help Rod. I read the instructions on calibration but the process presumes one's computer gives the low battery warning and then goes to sleep, which my computer doesn't do. How can I calibrate it then?

    As an additional piece of information, both times the computer shut down while I was watching online video demos of car reviews. So the processor was working pretty hard. Would this explain the immediate shut down?

    Also: I just checked my Apple Care agreement online and see that it doesn't expire until April. That means my computer is just about 3 years old. So I'm still covered if I take it in to get tested.
  • Rod Hagen Level 7 Level 7
    Hi again Bluesygirl,

    As you say sudden shutdown can make calibration impossible in some situations, but you can sometimes overcome this by:

    1) leaving the computer running, with the automatic "sleep after xxx time" preferences in Energy Saver turned off, but with no applications running. If the battery hasn't quite reached the end of its life this can allow it to reach the normal low battery sleep point with out shutting down.


    2) repeating the calibration process again after the failure, and again not doing any real work on the computer after it has reached the point where you start to experience unexpected cut-outs.

    Whether it is worth going to this trouble (with a strong probability that you may still not be able to calibrate it, and that if you can the result will be simply to confirm that the battery needs replacing anyway) is a bit of a moot point in your case, though. It really sounds to me as if your battery is on its last legs, I'm afraid.

    Yep. Take it in for testing ASAP.

    And yes, watching on-line "Flash" videos is just the sort of thing that will push a dying battery over the edge.


  • Andrew Wolczyk Level 5 Level 5
    When you say its shutting down, do you mean its going to sleep or completely shutting down?
  • inkaman Level 1 Level 1
    I'm having this same problem where my laptop just suddenly shuts off, completely, at right around 30% battery life.

    The computer is just over a year old and the battery info is:
    Charge Information:
    Charge remaining (mAh): 1370
    Fully charged: No
    Charging: Yes
    Full charge capacity (mAh): 2926
    Health Information:
    Cycle count: 285
    Condition: Check Battery
    Battery Installed: Yes
    Amperage (mA): 842
    Voltage (mV): 12147

    Honestly I don't know what most of that means. Is cycle count high or low? Do I just need to replace my battery or is it something different? I think a battery should last more than a year, right? Bluesygirl's battery seems to have lasted much longer than mine.
  • Rod Hagen Level 7 Level 7
    Your cycle count is actually a bit on the high side if you have only had the battery for the year, inkaman.

    Your battery full charge capacity (2926mAh) is down to about half of that it had when it was new (around 5600mAh) if this is a 15" from the "pre-unibody" days.

    You almost certainly need a new battery, I'm afraid. Take it for testing to your nearest Apple AASP or Apple Store.


  • megorama Level 1 Level 1
    I am having the same problem even after purchasing and installing a new battery. The battery life is as expected but there is no warning before it runs out and it just automatically shuts down - does not sleep - just shuts down in the middle of working on it. I'm on a MacBook Pro 15" purchased in late 2008. ANyone have any thoughts on how I can get the warning back?
  • Rod Hagen Level 7 Level 7
    Hi megorama,

    Try calibrating the battery. Follow the instructions at http://support.apple.com/kb/HT1490 , but before the battery gets into the sort of zone where it shuts down unexpectedly quit all of your applications (this should reduce the risk of a sudden power load causing it to quit unexpectedly during the calibration process itself).

    Don't worry too much if it still shuts down without warning anyway at this point in the calibration, but follow the remainder of the steps outlined in the article (letting it rest for five hours without power after it sleeps or shuts down, and charging it up fully).

    If the problem is still occurring after a full calibration try resetting the SMC (see http://support.apple.com/kb/HT3964 ), removing and replacing the battery, and try the calibration again.

    You should aim to re-calibrate your battery every couple of months.