Can anyone explain Genius Bar's battery diagnostic tool?

Discussion in 'Mac Basics and Help' started by g35, Sep 4, 2013.

  1. g35, Sep 4, 2013
    Last edited: Sep 4, 2013

    g35 macrumors 6502a

    Joined:
    Dec 13, 2007
    #1
    I took my Macbook in for an unrelated issue and also asked the Apple employee about my weak battery life (2.5 hours on a 2 year old battery). He hooked it up via thunderbolt to some diagnostic tool and looked at the battery section (looked like the attached drawing). Does anyone have some idea what the colors and scales are, and what the values are that separate green from red and red from yellow?

    I'm guessing green was normal battery, yellow was replace soon and red was service battery, horizontal scale was #cycles and vertical scale was battery health, 80% health is where green meets red and 300 or 500 cycles is where red meets yellow. I might have mixed up red and yellow in my memory.

    Mine fell on the black dot (which makes sense since coconutbattery and istat pro say 81% health after 270 cycles).

    I'm assuming they use this as a visual indicator of whether or not to replace the battery under warranty...eg. if it's green, no replacement. If it's red, replacement. But I didn't ask and this is just a guess.

    I know this is a somewhat frivolous thread but I was hoping he'd approve a replacement since mine is draining at 3-4x the rate Apple suggests it will (they say their batteries will retain 80% battery health after 1000 cycles) but he said no to a replacement, that my battery is normal.
     

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  2. Mr Rabbit macrumors 6502a

    Mr Rabbit

    Joined:
    May 13, 2013
    Location:
    'merica
    #2
    Basically the green indicates a good battery, the yellow indicates a consumed battery (cycle counts have exceeded the rated number allowed) and the red indicates a battery that has failed.

    If the dot ends up in the green then it is deemed to be operating within reason and is considered to be good without need for replacement.

    If the dot ends up in yellow then it is deemed to be "old age" for a battery, maybe with a cycle count of 400 when the battery is only rated for 300 (these numbers vary between models). If the battery is showing signs of failure or weakness but is in the yellow then such failures/weakness are somewhat expected due to the age or amount of usage the battery has experienced.

    If the dot ends up in red then your battery has likely failed prematurely. I forget the percentage but the test has basically found that it's capacity is lower than X% of it's original capacity even though it's under the rated cycle count. For instance, if your battery is rated for 300 cycles but only has 10% of it's original capacity despite only having 150 cycles then it will fall under the red.

    As far as the x/y axis location of the dot, I believe you're correct.

    Hope that helps. In defense of the Genius/employee, battery related issues are very hard to deal with/explain. Everyone has different usage habits, everyone has different perceptions of how the battery should perform, etc. This diagnostic looks at capacity & cycle count, the only two real metrics you can actually measure with a battery. You "could" request that they check in your Mac and run an extended battery test on it (usually putting the Mac under light stress and timing how long it takes to completely drain while under Genius supervision, but more than likely they would default back to the results of this diagnostic. It looks like you're right on the edge, you might check back with them in a month or two.
     
  3. g35 thread starter macrumors 6502a

    Joined:
    Dec 13, 2007
    #3
    Thanks for your reply! I agree with you on the defence of the genius but I really do try to take care of my batteries so that's the reason his explanation upset me (eg. Don't leave it plugged in, don't do full drains, etc)

    I still have a year left on AppleCare so I will take it in in a few months if it drops below 80% way before it reaches 1000 cycles (the expected life for a 2011 MBA battery) which seems likely...at its current rate I'm guessing it will drop into the red before it reaches the yellow. I hope the genius will not attribute the battery performance to heavy use when my cycle count really doesn't reflect that.
     
  4. Mr Rabbit macrumors 6502a

    Mr Rabbit

    Joined:
    May 13, 2013
    Location:
    'merica
    #4
    I wouldn't worry too much, that test is a quick way for Genius' to see if a battery is good, bad or consumed. Beyond that they typically don't put much thought into it unless the customer has had a multiple bad batteries or if there is some other related issue at hand. Basically, if they see red and the Mac is under warranty then it would be more work for them to argue against replacing the battery than to just replace it.
     

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