calibrate battery

Discussion in 'iPhone' started by SeVeN, Oct 27, 2007.

  1. SeVeN macrumors 6502a

    Aug 8, 2006
    San Jose
    should i do this often? and is calibrating an iPhone battery just like doing it on a MBP?

  2. lavrishevo macrumors 68000


    Jan 9, 2007
    iPhone batteries DO NOT need to be calibrated. Lithoum-ion batteries do not have a memory. Also the deeper the charge the worse it is for battery life. Charge as often as possible will make your battery last longer. Just look it up if dont believe me.
  3. kdarling macrumors demi-god


    Jun 9, 2007
    First university coding class = 47 years ago
    Yes, all Li-Ion need calibration.

    Once a month, charge it fully, discharge it fully, then charge again.

    That will keep its internal meter calibrated, so it doesn't claim it's out of juice when it's not.

    (This is not conditioning. The battery slightly miscalculates its own charge each day, and the errors pile up over time.)

    Prolonging Lithium Batteries
  4. JonHimself macrumors 68000


    Nov 3, 2004
    Toronto, Ontario
    I enjoy two completely contradictory posts that both appear to be very confident in their responses
  5. kdarling macrumors demi-god


    Jun 9, 2007
    First university coding class = 47 years ago
    Except that mine has a link, which gives it authority ;)

    A related story:

    We had thousands of a certain handheld in the field. Huge battery; should be good for all day (or two) usage easily. After a half year or so, many units began to die by early afternoon. It was a mystery at first.

    Finally the manufacturer figured out that the batteries were lying to the handheld. They claimed they were down to a certain level, at which the handheld popped up the "I have to shut down soon" warning.

    But the batteries actually were still full of charge. Their internal calibration was simply way off after months of usage. Worse, the batteries had an internal bug that prevented a full charge cycle from recalibrating them as well as it needed to.

    In the end, we had to do a remote software update to the handheld, and lower the "charge level" at which the low-battery warning kicked in. All so that the units could continue to use the lying batteries.
  6. WaltFrench macrumors newbie

    Feb 15, 2007
    Contradictions Removed

    Here's an interpretation that reconciles the two sides:

    Li-ion batteries indeed SHOULD NOT be completely discharged. Well-designed devices will shut down to prevent a total discharge. Some charge will be lost even in no-power-used situations, so you might follow Apple's advice of connecting the phone to a charger, then shutting down the phone (leaving the charger going), if you're going to leave the phone for more than a few days, in which case you could otherwise completely discharge the battery.

    The device software can get confused about how much charge the battery is holding. Batteries are designed to have a constant voltage (1.5V for the AA's in your maglite), but voltage declines slowly when the battery has less oomph left. The charge indicator guesses from the voltage how much capacity is left, but it's a bit of guesswork-- the only way to know for sure it to drain all the capacity. So people often run the battery down so the device can watch the measured capacity versus OK, the phone actually shut down.

    Because the phone protects the battery from total discharge, it does not risk the battery life-- that's down, not out. It DOES count as one of the limited number of battery uses that it'll deliver in its lifetime, so the increased understanding of your battery status had better be worth cutting its life by 0.2%. Once every month or two could fit most people's definition of that, and indeed, Apple has a battery info page with a reminder reminder to re-calibrate their iPod or MacBook batteries once a month.

    Note, the page does NOT specifically mention the phone; perhaps Apple has figured this is too much for your average phone user, perhaps they have some clever alternative so the meter shows more accurately what's going on, or even, perhaps, they haven't bothered to update it since the phone was introduced.

    So no, do NOT completely discharge Lithium Ion batts, but YES, do completely use the available charge from time to time if your device is saying you're down to only, say 15% when you haven't really used it enough to justify that.

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