Battery health 96% with only 18 cycles

Discussion in 'MacBook Pro' started by Trinity, May 22, 2009.

  1. Trinity macrumors regular


    Sep 10, 2005
    Barcelona - CAT
    About a month ago I bought a brand new unit of the last version of the old 17" model. iStat Pro recognized the battery as new with 100% health. 30 days later it shows 18 cycles and 96% health. To what extent this information is trustworthy? Can I ask for a replacement if that fast aging process continues?
  2. MarkMS macrumors 6502a

    Aug 30, 2006
    You can ask for a new one as long as it's still under Apple Care. They'll ask you a few questions about the battery and then tell you if they can exchange it for you. But try calibrating the battery before you ask and see if that helps.
  3. mikes70mustang macrumors 68000


    Nov 14, 2008
    Its not super accurate. It fluctuates, mines gone down to 91 then back to 99, then to 94. And that is after calibrating. Just calibrate your batt. and if it constantly stays under 80% then get it replaced by apple
  4. gr8tfly macrumors 603


    Oct 29, 2006
    ~119W 34N
    I don't think they'll consider replacement unless it's like 50%, or thereabouts.

    I don't use iStat much, but it's probably the same as Hardware Monitor: "current maximum capacity / original capacity" - in my case 12743mAh / 13000mAh = 98%, and I only have 4 cycles. System Profiler will also give you a general "Condition" repor. I dotubt "96%" is beyond the normal variance. I have the same machine, and I see 98% and 100%.

    If it behaves the same as previous systems, try unplugging the power adapter until the remaining percentage drops to 95%, then plug it back in and see if it gets to 100% (after charge complete).

    If you're not seeing any diminished operating time, it's nothing to worry about.
  5. jmann macrumors 604


    Dec 8, 2007
    bump on a log in a hole in the bottom of the sea
    Just use/enjoy your computer, and stop worrying about it. ;)
  6. pdxflint macrumors 68020


    Aug 25, 2006
    Oregon coast
    My new battery had slowly dropped from 100% to 96% capacity after 6 weeks and 10 cycles. I normally use it plugged in, but once a week or maybe a little more often I would run it on battery... and run it down to 5%, then charge it back. Doing this didn't seem to prevent the apparent drop in "health."

    Then, I started pulling it off the power and running it down to 50-65%, then connecting it back again to top it off. Sometimes I'd run it down to 80%, then charge it back again. After doing this over a week or so, suddenly my battery "health" rose to 99%, then today it went over 100% (5617mAh capacity, 5600mAh original capacity.) It seems the battery likes to be exercised regularly, and moderately. Full discharges and recharges aren't as good as partial discharges of varying amounts - from 10% to 90%, anything in between - just don't always run it dry every time you use the battery. I'm talking about normal use, not calibration. So, it seems that just using the laptop as a portable, letting the battery work a bit every other day or so keeps it much healthier over the long haul.
  7. revs macrumors regular

    Jun 2, 2008
    I agree with this. The percentage will fluctuate. I've seen drops and jumps of 15-20%. People seem very obsessed with battery % on MR. There is really no need!!
  8. RKpro macrumors 6502

    Oct 27, 2008
    I'm at 23 cycles, 94%. But it just doesn't matter. If you paid $2000 for a laptop, you shouldn't have a problem replacing the battery for $130 every 1-2 years...
  9. miles01110 macrumors Core


    Jul 24, 2006
    The Ivory Tower (I'm not coming down)
    You've got basically zero chance of getting a battery replacement at 18 cycles/96%. The aging process isn't linear anyways.

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