Is it Bad to let your battery die before charging???

Discussion in 'iPhone' started by VideoNewbie, Jun 21, 2009.

  1. VideoNewbie macrumors 6502

    Feb 6, 2009
    i was always told you should use your battery all the way down to 0% before you charge it and that this is better for the battery than using it up until say 20% and then re-charging it.... is this correct with the iphone?

    also no matter how long i charge the phone the battery will only go as far as 99%...what gives?
  2. Rat-Boy macrumors 65816


    Jul 28, 2008
    I plug my phone in every night.

    Whether it is on 20% or 80%.

    Only once a month do I make sure to drain it till it cuts off and then charge it.

    I have been doing that for a year and I haven't noticed any real battery performance drop so far.
  3. Mpalmieri1203 macrumors member

    Jul 4, 2007
    I've used all 3. The battery functions real well in all of them. Even the 2g. I wouldn't obses about battery health too much.
  4. labman macrumors 604


    Jun 9, 2009
    Mich near Detroit
    actully good for the device

    to go completely out at least sometimes while lithium no longer have the memory problem of nickle batteries it helps build battery life. :D
  5. zacheryjensen macrumors 6502a


    May 11, 2009
    This is very wrong, you should never ever let a lithium ion battery become 100% discharged, it will significantly reduce the total lifetime of the battery (as in, how many times you can recharge it fully.)

    Lithium Ion batteries are popular in consumer devices for the simple reason that they do not take much damage from charging from the middle of usage, they do not have a "chemical memory" in the same way a NiMH or NiCD battery have. However, that said, you should occasionally give it a good stretch, down to about 10-15% and then charge to 100% all at once to ensure it maintains full battery life capabilities.

    As for the 99%, I wouldn't worry about that, battery remaining indicators are only estimates anyway. These estimates are based on variations of voltage discharged from the battery at any given time and various situational factors can alter this and it doesn't indicate the true battery life.

    *THAT* said, if you are using a case and the iPhone is getting hot in that case, you will destroy your battery far more quickly. Heat is another primary enemy of lithium ion batteries (which is why the case design allows for heat to flow out easily through the connected plastic hence making the phone warm to the touch during heavy use.) If you prevent heat dissipation with a case or similar covering you'll reduce the total life span of your battery.

    Apple has their own tips that are similar to mine at
  6. JaySC macrumors member

    Jun 16, 2009
    E TN
    I always knew most of this to be the case, but was also always told to let it run down ALL THE WAY to keep ALL OF THE CELLS working and healthy. I'm not saying that you are wrong, as you seem to know what you're talking about, but would you mind explaining the science behind this?

    I'll do my own research here, but as someone responsible for selling items with lithium ion batteries, it would be nice to know what the real truth is. By your explanation, I've been lying to customers.
  7. TLewis macrumors 65816

    Sep 19, 2007
    left coast, US
    It won't hurt, but it really won't do anything either (except to recalibrate the "battery capacity" circuitry, and that supposedly only needs to be done every 30 charges or so). Unlike older battery technologies, lithium-ion batteries don't suffer from any "memory effect".


    I just charge my phone every night.
  8. cobalt135 macrumors regular

    Dec 28, 2008
    I would not worry too much about fully discharging you iPhone battery causing damage. I am sure that the power management shuts the phone down before a deep discharge happens.

    In any event charge the phone whenever you see fit as a lithium ion lifespan is mostly cycle dependent. Full cycle would be when the phone is fully charged to where the phone would shutdown from low batt. If you started fully charged and ran the phone down to 50% and recharged. That would be 1/2 a cycle for instance.
  9. SephirothXR macrumors 6502

    Nov 27, 2008
    Do INCASE Slider cases cause excess heating? That's the whole reason why I kept taking it out everytime I charged it, and because of that, it put 2 scratches on my iPhone :mad: Now I just keep it on all the time, but do they hurt the battery?
  10. scaredpoet macrumors 604


    Apr 6, 2007
    As long as you regularly use the battery, you should be fine and there is little you can do in terms of charging habits that will make the battery life any worse or better.

    Probably the only bad thing that you shouldn't do is keep the phone in a constantly charged or discharged state for days and days. If you regularly use the battery during the day and top it off at night, you're fine.

    Depends on just how hot the phone gets. I suspect though, that the iPhone will not charge if it's too hot.
  11. VideoNewbie thread starter macrumors 6502

    Feb 6, 2009
    how long should we leave the battery charging for a full charge?
  12. Knowlege Bomb macrumors 603

    Knowlege Bomb

    Feb 14, 2008
    Madison, WI

    The iPhone shuts itself down and maintains enough power to keep it "alive" for a good amount of time. I can't and won't spout numbers due to lack of specific knowledge but when you attempt to power on after the phone has shut down you'll see it still has enough power to display the battery image with the flashing red sliver until it is completely dead.
  13. doobi18 macrumors 6502

    Dec 31, 2006
    Sydney, Australia
    Regardless of exactly how you treat your battery, it will still generally outlive the rest of the phone in decent shape... so it's actually kinda irrelevant. :D

  14. iphones4evry1 macrumors 65816


    Nov 26, 2008
    California, USA
    Yep, that's right. When I first bought my iPhone, I read on Apple's website their recommendations. It said to let the iPhone run all the way down at least once per month.
    (the iPhone auto-shut off shuts off before the battery is all the way discharged to protect it).
    But if you discharge it every time, you are actually decreasing the long term life of the battery (it says something like "1000 full charge cycles" or something like that). You also inconvenience yourself if you discharge all the way every time. Since I bought my iPhone, I have been just charging it from half way (or wherever it is at) every time, but once a month I discharge it all the way and charge it all the way back up. Something that is good for a Li-ion battery is to let it charge all the way up every time. When it is at 50% and you decide to plug it in, don't unplug it at 95% unless you have to (it's not going to destroy it - it only effects it very slightly, but rather let it charge to 100% first.
  15. KidFresh macrumors regular

    May 11, 2009
    So am I or am I NOT suppose to keep the phone plugged into a charger for the most part of the day to prolong the battery's life.
  16. jmpage2 macrumors 68040


    Sep 14, 2007
    This is an old myth that is only true for old school nickel cadmium batteries, please do a google search. You will actually harm a lithium ion battery more by power cycling it than by topping it off every night.

    Periodically you need to run the battery all the way down so that the sensor in the phone and the battery get re calibrated to each other to show correct battery life.
  17. jmpage2 macrumors 68040


    Sep 14, 2007
    The battery needs to be exercised for optimum function, which means running it down a bit every day, but this does NOT mean;

    1. Leaving it plugged in all the time (will ruin the battery).

    2. Draining it 100% and then charging it all the time (will ruin the battery).
  18. KidFresh macrumors regular

    May 11, 2009
  19. jcdDigix macrumors member


    Jun 9, 2008
    I was always confused on that subject. Now I kind of get an idea on what whole battery life thing. Thanx guys. :cool:
  20. brtbendele macrumors newbie

    Feb 14, 2008
    If you're selling items with lithium ion batteries, you might be leaving them on the shelf for long periods of time in a powered down state. If this is the case, you ought to keep the phones near a 50% charge. It is not healthy to leave lithium ion batteries without cycling them for long periods of time (i.e. weeks at a time). It is worse for the battery health to store it in a fully charged state or fully drained state for long periods of time. They "like" to sit at around 50% charge when idle.
  21. PNutts macrumors 601


    Jul 24, 2008
    Pacific Northwest, US
    <sigh> This debate happens on every battery thread. Until very recently Apple's website recommended that you let the battery run down until the device shut off once a month. (This doesn't mean the battery was completely discharged for all the battery theorists out there.) Apple changed their battery pages and removed the reference to a monthly complete discharge.

    So here's what Apple recommends now. Once a month go through at least one charge cycle. A charge cycle is using and recharging 100% of battery capacity. So you can use 100% in one day or 10% daily for 10 days or 5% daily for 20 days.. It doesn't matter how much you charge it or when you charge it in between or how long it's plugged into the charger. Just make sure your monthly usage adds up to 100%. For example, you don't want to only use 1% of the battery per day, that adds up to 30% and that's not enough.

    Feel free to jump on me, but this is simply the Vendor's recommendation.


    Not true. This was Apple's recommendation until very recently (month or two). There is no harm letting your device run until it shuts itself off.
  22. KaijuRed macrumors regular

    Jul 16, 2013
    This thread is 4 years old...
  23. PNutts macrumors 601


    Jul 24, 2008
    Pacific Northwest, US
    And? It's full of bad information that's now on page one.
  24. Carlanga macrumors 604


    Nov 5, 2009
    Welcome to 2009, hope you enjoyed your stay. :)
  25. xraytech macrumors 68030

    Mar 24, 2010
    That is the WORST thing you can do with you iPhone's battery.

    Keep it simple, plug your iPhone in to charge before you go to sleep. That's it, nothing more to do.


    A little long winded but here you go...

    And here's the Money Shot

    Over-discharging Lithium-ion

    Li-ion should never be discharged too low, and there are several safeguards to prevent this from happening. The equipment cuts off when the battery discharges to about 3.0V/cell, stopping the current flow. If the discharge continues to about 2.70V/cell or lower, the battery’s protection circuit puts the battery into a sleep mode. This renders the pack unserviceable and a recharge with most chargers is not possible. To prevent a battery from falling asleep, apply a partial charge before a long storage period.
    Battery manufacturers ship batteries with a 40 percent charge. The low charge state reduces aging-related stress while allowing some self-discharge during storage. To minimize the current flow for the protection circuit before the battery is sold, advanced Li-ion packs feature a sleep mode that disables the protection circuit until activated by a brief charge or discharge. Once engaged, the battery remains operational and the on state can no longer be switched back to the standby mode.
    Do not recharge lithium-ion if a cell has stayed at or below 1.5V for more than a week. Copper shunts may have formed inside the cells that can lead to a partial or total electrical short. If recharged, the cells might become unstable, causing excessive heat or showing other anomalies. Li-ion packs that have been under stress are more sensitive to mechanical abuse, such as vibration, dropping and exposure to heat.

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