86% battery life shuts macbook pro

Discussion in 'MacBook Pro' started by scotty96LSC, Mar 2, 2010.

  1. scotty96LSC macrumors 65816

    scotty96LSC

    Joined:
    Oct 24, 2007
    Location:
    Charlotte, NC
    #1
    I have a 3.5 year old macbook pro. Seems that when I'm using the battery, which is rare, the mbp shutsdown when the battery gets down between 86-89% charged. When plugged into the wall no problems.
    I have tried all these things from this earlier thread, but still won't stay booted.
    Bad battery? The battery is about a year old.
     
  2. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #2
    1 year shouldn't have done anything to the battery.

    What does coconutbattery say about the battery health?

    And/or what does About this Mac > More Info > Power say under
    - Full charge capacity
    - Health information

    (hint - you should be looking for >5000 mAh capacity depending on model and "Normal" health)

    When you plug the charger in does the AC Charger info down at the bottom say sensible things about charging & connected?
     
  3. scotty96LSC thread starter macrumors 65816

    scotty96LSC

    Joined:
    Oct 24, 2007
    Location:
    Charlotte, NC
    #3
    All looks normal to me for a 1-year battery.
    •Current battery charge 4111
    •Max battery charge 4151
    •Current capacity 4151
    •64 load cycles
    •75 percent of orginal battery
    •40 month old mac
     
  4. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #4
    Weird, could be bad battery but it's had an easy life so far

    What about voltage, should be 12500-12600 mV when fully charged & disconnected from the plug for a couple of minutes. You will have to refresh System Profiler - cmd-R.

    As you run it down to the 86% or whatever shutdown point, does the battery voltage drop a lot? At 86% the voltage should still be really near 12500.

    If it drops a lot below 10000 I bet that the Mac or the battery logic will stop delivering mA (switch the machine off) to save the battery from "deep discharge" which can kill Li-poly batteries (apparently) -> see link below

    http://www.batteryuniversity.com/partone-12.htm
    "Extreme low voltage must also be prevented. The safety circuit is designed to cut off the current path if the battery is inadvertently discharged below 2.50V/cell."

    Most of the Macs I have come across have 3 cells in series to make 12.6 V when fully charged, so this lower limit will be 2.5 x 3 or 7.5 V (7500 mV)
     
  5. scotty96LSC thread starter macrumors 65816

    scotty96LSC

    Joined:
    Oct 24, 2007
    Location:
    Charlotte, NC
    #5
    After a couple of minutes and disconnected from the power here is what I get:
    [​IMG]
     
  6. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #6
    I think "check battery" is an Apple euphemism for "your battery is toast"
    Sorry

    The voltage is quite low, 11800 when nearly full. My nearly new battery is about 12500. I bet it drops like crazy.

    Just out of interest, was it an Apple branded battery? or a copy? What happened to the original battery? (you said the Mac is older than the battery)
     
  7. scotty96LSC thread starter macrumors 65816

    scotty96LSC

    Joined:
    Oct 24, 2007
    Location:
    Charlotte, NC
    #7
    An apple battery. The original battery would only last about 30 minutes so I got a new one. No biggie, I will get the old company credit card out and snag a new battery from Apple. Thanks for the help.
     
  8. neutrino23 macrumors 68000

    Joined:
    Feb 14, 2003
    Location:
    SF Bay area
    #8
    Sounds like a bad battery. I've had two similar cases though not with quite that level of charge. It would get down to something like a little less than half discharged and suddenly the machine was dead. Sudden death while the battery still seems to have charge looks like a symptom of an end-of-life battery.
     

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