IMPORTANT: don't ever discharge your battery completely.

Discussion in 'iPhone Tips, Help and Troubleshooting' started by utneon, Jan 24, 2011.

  1. utneon macrumors regular

    Jan 19, 2011
    ok, this has been bugging me for these last few years and i must tell people what no to do with lithium batteries so here i am to help many of those who don't know this.


    So, as you may notice, it really is as the post says, so i will give an explanation in advance. Back in the days where all the mobile phones started, like nokia, samsung, etc... they used those first batteries Ni based... Same is true for those batteries you find in your apple wireless mouse and toys. These batteries must be discharged completely because they have memory cycles and if you charge them when they're at half they will memorize it and lose capacity.

    However lithium batteries (you use them in your phones and notebooks today) don't use the same techonology. As you may know, they're lithium batteries, and they have a lifetime of "x" cycles.

    Why is that? well, for each cycle the battery loses a bit of it capacity percentagen due to the low voltage resulting in damaging cells in the battery. i think cells is the correct word.

    Q: So, what happens if you discharge it completely?
    A: Your battery will have very low voltage, and that will result in overheating your battery, consequently damaging a lot more cells than it should in normal usage.

    So that's why you should never discharge a battery completely, either it's your phone or notebook or whatever device you have with lithium technology in battery.

    I'm robotics engineering expertise, and work a lot with radio controled devices, so we investigate a lot for battery solutions, that is one of the basics usage for lithium batterys.

    There are some lithium magnesium batterys being developed that will not suffer from this problem, but they are currently very expensive for commercial use in masses.

    Tip: Charge your batteries when they are close to 10% at maximum, and if you will not be using your device for a long time, keep it stored with the battery around 50%. having max charge or low charge is bad for the battery. I Hope this information helps everyone...

    Sorry if my english doens't satisfy you, it's not my native lang.
  2. Intell macrumors P6


    Jan 24, 2010
  3. TEHi macrumors regular

    Jan 6, 2011
    This is true and applies with Lithium Ion and Lithium Polymer batteries, but mostly if the cells are unprotected.

    Unprotected means the battery does not have a internal circuity to prevent it from overcharging 4.2v, and discharging from 3.0v. Cellphones and high-tech equipment, or sometimes the battery itself will contain this protection circuity, it will prevent your battery from being damaged by cutting off the current flow at certain voltage. Once the battery voltage goes near 3.0v the celphone will shutdown, my iphone 4 goes off when hits 2%.

    Many blogs and forums will sugest users to fully discharge their battery at least once per month. This is not really necessary. A Lithium polymer battery will only benefit from this in the first 3-5 cycles as it will "grow" to its optimal capacity.

    Don't worry, you can still "fully" discharge your battery without doing serious damage to the cell, but you must avoid this if possible. :D
  4. utneon thread starter macrumors regular

    Jan 19, 2011
    thank you for adding extra technical information :)
  5. wfriction macrumors newbie

    Jan 24, 2011
    Thanks for that!
    Strange that they say in the iPhone manual to do a complete discharge once a month though.
  6. Bacong macrumors 68020


    Mar 7, 2009
    Westland, Michigan
    Ugh. You CAN'T FULLY discharge the battery. The software does not allow it. When the iPhone dies, it still has a tiny charge. This thread is useless.

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