rMB battery vs mains

Discussion in 'MacBook' started by objektør, Mar 28, 2017.

  1. objektør macrumors regular


    Nov 25, 2014
    At home
    I have been using my rMB 90% of the time on battery. Roughly 20 cycles a month. (458 cycles in 23 months). Battery health has been fluctuating quite a bit all the time. (sometimes more than 5% on one day).
    But it has last me through the day most of the times. So I am pleased with that.
    Lately I have been able to use the rMB mostly on mains 90% of the time. Only 2 cycles on the battery this month. The battery health is much more stable (fluctuating max 1-2% only on a daily basis).
    I wondered if those of you who have been using their machines mostly on mains have (much) better battery health after 2 years than those who have been using the battery most of the time. After two years of use my battery health lies around 80%. How about those who have used it on mains?

    Obviously you will have less cycles but do you get more hours out of your battery when you use it. Altogether I might have lost 2 hours of use on a full charge since day one (but this is a very rough estimate).
    I am planning to get an external battery pack for those occasions when I am not able to use it on mains over considerable time and thus save what I have left on the rMB battery as much as possible so that I might avoid a new rMB battery. I live very remote and there is no Applestore/service nearby. Sending it in would at least take 3 weeks altogether. Beside that I would save quite some money (250€ vs 60€ for a battery pack with usb-c).
  2. polee macrumors 6502a


    Jul 22, 2008
    I have 101 cycles, I have this macbook for two years now (MacBook 2015), and about 85 percent battery health.
  3. ryguy92000 macrumors regular


    Sep 20, 2014
    Salt Lake City, UT
    do NOT leave your machine on main power. this WILL destroy the battery. Li-Ion cells need to be fully dissipated (to the point of the machine fully dying) and recharged at least once every 6 months. Also conduct a Pram and SMC reset on the machine as well, and you will be back in business.
  4. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    What wears out these batteries is battery cycles. So a full discharge, the recharge is one cycles. So the fewer cycles you use the longer it will last. I had a 2014 rMBP that was on the charger more than 95% of the time and it still had 97% battery capacity when I sold it.

    That said, don't obsess over it. If you need to use it portable, go ahead and don't sweat it... the battery will eventually give out anyway.

    Do not intentionally fully discharge as that adds unnecessary cycles to the battery.

    Here are some links with info from Apple that might help you.



  5. Enrico macrumors 6502


    Feb 6, 2007
    Milano / Roma
    Keeping it always at 100% decreases its maximum power over time, I just experienced it myself with a premature health drop.
    I have read online that using it between 40% and 80% with occasional discharges in-between should lead to the maximum lifespan of a lithium ion battery.

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