New 1.5 month old MBP 17. Battery health only 96%, what gives?

Discussion in 'MacBook Pro' started by sparkie7, Jan 2, 2009.

  1. sparkie7 macrumors 68010


    Oct 17, 2008
    75 Cycles on iStat Pro and already my batt health is down to 96%.

    There is so much CONFLICTING information on here and on the www about the best method to manage laptop battery health.

    Do you use down to like 10-20% and charge to 80-90% to avoid charge cycles, others say its cummulative, others say do full drain and full charge everytime.. others say to keep charged all the time * sigh *

    any solid advice out there that can be trusted :confused:
  2. CaptainCannabis macrumors regular

    Oct 29, 2007
    The battery health fluctuates.

    My previous MBA, for example, one charge said 98%, after a few cycles it said 94% then it went back to 98% or to 97%, etc.

    Same thing with my late MBP and old PBs.

    Also, battery health tends to go down with time and settle at a percentage for a long time, usually never lower than 90%... I would say that this is like the real or default or something (I really don't know how to call it) battery life. My guess is that yours is going to fluctuate around 94-98% for the next 6-12 months.

    I wouldn't worry about the battery life unless you see it quickly starts dropping below 90 or 85.

    PS: I might be wrong though... all of this is based on my experience, but it has always been right.

    EDIT: Charge drain is cumulative (I think). Have it plugged in whenever you can, when at full charge the battery doesn't get used and you avoid unnecessary usage.
  3. Chunk72 macrumors member


    Mar 16, 2008
    Durham, UK

    My mbp is the same, right after I got it the health dropped to 96% then 94% and has been that way for weeks, then this morning it is back up to 100%.

    Just one of those things.

  4. sparkie7 thread starter macrumors 68010


    Oct 17, 2008

    Thanks CC. Based on this reasoning is it ok to have my MBP plugged in all the time? I think I have read people saying this is NOT healthy :confused:
  5. sparkie7 thread starter macrumors 68010


    Oct 17, 2008
    thanks for the reply Chunk. But I havent seen my batt health go up over the period since i got it. uts been decliniing. Snifff. I think my battery is dying :(
  6. CaptainCannabis macrumors regular

    Oct 29, 2007
    I mean, everyone will say something different. Based on my experience this is what has worked for me, and other people based on theirs might say something different.

    My MBA has like 120 charges since Feb 2008 and I have like 96% or 94% health right now, cant exactly remember (Im on my MBP abroad :( ). Ive used it everyday and had it on for like 9 hours every day until like a month and a half ago when I bought my MBP. I don't have many cycles because I've only used it unplugged when it was strictly necessary.

    The best thing you can do is just forget about the battery and then when you see that instead of lasting 2 hours it lasts 1, replace it.

    My MBP right now:

    1.5 month old too, 20 cycles and 97% health.

    Edit: srry no, its 98% (i read the charge (97) instead of health(98))
  7. darngooddesign macrumors G3

    Jul 4, 2007
    Atlanta, GA
    You have a year to worry if its a bad battery, don't sweat it. Apple has always been good to me about replacing questionable batteries.

    As far as care, its cumulative. A charge cycle is empty to full so if you charge 75% > 100% four times its one cycle. Its a bad battery if after 300 cycles you have significantly less than 80% life left. Every other month run the battery from full to completely empty, and then back to full. That helps calibrate the battery so your computer displays its charge correctly.

    I keep mine on a charger most of the time, but I don't worry running it on battery either. I keep my laptops for several years so I just assume that at some point I'll have to buy a new battery.
  8. kastenbrust macrumors 68030


    Dec 26, 2008
    North Korea
    Istat is usually innacurate by around 1-5% because the ionic capacity of lithium fluctuates over time, mainly due to heat, so on a cold day it will hold more charge than a hot day.
  9. aiterum macrumors 6502


    Nov 17, 2007
    United States
    wow, i've had mine for only 10 months and i'm down to 86% health
  10. darngooddesign macrumors G3

    Jul 4, 2007
    Atlanta, GA
    How many charge cycles? If it's under 80% with less than 300 cycles Apple will replace it.
  11. sparkie7 thread starter macrumors 68010


    Oct 17, 2008
    thanks for the replies. I'm not exactly sure if I'm any clearer on the issue lol :D

    so is it ok to have my MBP plugged in 100% of the time? and if it goes green on the indicator ie. 100% charged, that the power gets routed to the AC adapter instead of the battery. Hence not frying or over-cooking it?

    Either way, one message is clear. Use it htf* you want. and if it goes t*ts up, just buy a new one pal.

    *However the f*ck
  12. Hot Snowboarder macrumors 6502

    Jan 2, 2009
    Behind you...!
    Yep leave the battery in alllllll the time. Condition it every 20 cycles or so.
    There's an article on apples support website bout how to condition the battery, someone will find it for you (i've lost it).
    I've had my MBP for 11 months now and the stats are:
    cycles: 101
    health: 92%

    The batteries are relatively inexpensive to replace. Every 200 cycles or so you should look into a new battery.
  13. sickmacdoc macrumors 68020


    Jun 14, 2008
    New Hampshire
    Well I would trust Apple's recommendations about calibrating your battery periodically so that the % estimates and such are accurate. You can find out more info about that by looking in your owner's manual or in the Apple support document here (look at the bottom section regardiing MBs, MB Airs and MBPs).
  14. darngooddesign macrumors G3

    Jul 4, 2007
    Atlanta, GA
    1. Its ok to leave it plugged in all the time for the reasons you mentioned.

    2. Calibrate it once a month.

    3. If it drops below 80% in less than 300 charge cycles Apple will replace it.

    4. When it goes t*ts up in two or so years buy another.

    PS. Apple designed them to not charge to 100% if you plug it in with 95% or more. That way the battery isn't cooking if its almost full but unplugged briefly.
  15. alphaod macrumors Core


    Feb 9, 2008
    I've had batteries literally die in 10 cycles and batteries at 100% health after 250 cycles, so it varies and it's all normal.

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