All iOS Devices Lie When They Say Their Battery Is 100%


Although it takes forever to fully charge, the new iPad costs less than $2 a year to run.
Unplug your iPad just after it reaches 100% and you'll lose up to 1.2 hours of battery life.

Shortly after the new iPad made its debut earlier this month, it was discovered that the way in which the device calculates its battery life is flawed. Despite telling you its charge is at 100%, your device hasn’t actually finished charging.

New data proves that in fact, your device isn’t finished charging until more than two hours after it reaches “100%,” and if you unplug it before then, you could lose around 1.2 hours of battery life. What’s more, it seems all iOS devices misreport their battery life.

The reason for this — as you may have guessed — is that the new iPads battery algorithm is “busted,” as ZDNet puts it. Ray Soneira, President of DisplayMate Technologies, did a little investigating and discovered that the new iPad will run for around 11.6 hours on a full battery. But its running time based on the 100% indicator is just 10.4 hours.

That’s a loss of 1.2 hours, or nearly 10%, if you unplug your device just after it reaches 100%.

According to ZDNet, Apple’s algorithm has always reported 100% battery life at a slightly lower capacity — normally around 97% — to keep the battery “safe and healthy.” It’s the same story for all of its mobile devices. The reason it’s more noticeable with the new iPad is that it features a much bigger battery:

The battery on the new iPad is huge, with a total charge capacity of a massive 42Wh or measured another way a monstrous 11,666 mAh. A 3 percent safety margin for the iPad 2 battery would be equal to around 210 mAh, while the same safety margin for the new iPad would be equal to 350 mAh.

When the new iPad first displays a 100% charge, it’s actually only holding around 90%, according to the report, and you’re getting 1.2 hours less runtime. It’s best to leave it charging overnight to get the maximum runtime the next day.

Soneira also found during testing that it takes around 5.5 hours to charge the new iPad when its battery is completely run down. That sounds like a lot, but try using the device at the same time and you’ll increase that charge time to a whopping 20 hours.

Because the new iPad’s battery is so big and it suffers from this issue, ZDNet expects to see Apple’s algorithm changed in a future software update, so that the device does show 100% until it actually reaches 100%.

  • Andrew Shipman

     Another reason to Hate Apple!

  • David Gallacher

    /\ You’re a retard.

  • Rmlgtp

    seriously who cares? and what’s the big deal it’s not so much lying as it is putting a perspective on the amount of battery people have left and if you’re that concerned about 99% or 100% and are ready to jump onto a charger when it says 99 the you have issues. obviously the only true 100% charge would be the second  you take it off the charger after it’s reached full capacity, from that moment on it’s decreasing from 100% instantly. Just because your cars gas gauge says “F” full doesn’t mean there isn’t room for another 1/32 of a tank. Get over it people. I’ve never assumed that 100% means 100% considering it can stay there for 10-20 minutes of use, meaning someone my phone or ipad or whatever it may be is using absolutely zero batter for those 20 minutes? obviously not, it’s just saying, “oh, your phone is damn near charged, no worries”. CHILL.

  • jordan pauly

    boo hoo… charge your iPad when you go to bed… wake up… good to go.

  • Kenton Presbrey

    Why because they decided to look out for the customers and keep the battery “Safe and Healthy” rather than just advertising 11.5 hours and letting people ruin their batteries? Yeah, what a bunch of jerks…


    If this article was never posted, 100% of folks would never have realized that 100% of your iPad’s battery life was being reported 100% of the time.

  • Terry Ng

    Then, use for 10.4 hrs

  • cyberb0b

    And Trolls..!

  • Mastawee

    Nearly all technology products using lithium ion batteries do a rapid charge, then a slower trickle charge to not over load the battery. For those committing negatively, if your holding a mobile device to type your comment, it does the same thing. So in essence your a hypocrite. Hypocrites that buy Sony or Dells that have exploding lithium batteries! This was noticeable do the the large capacity and ratio used in their algorithm.

  • Bob Whipple

    I agree that this is a tempest in a teapot. But where exactly does Apple say that overnight charging (leaving your charger on all night and not unplugging it as soon as the device reads 100% charge) will “ruin your battery”? This is not the first time I have heard someone say this, just wondering where it comes from.

  • Rob Music Love

    Simple Guidelines for Charging Lithium-based BatteriesA portable device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered and reflects the correct saturation current responsible to terminate the charge. A parasitic load confuses the charger.
     Charge at a moderate temperature. Do not charge below freezing.
     Lithium-ion does not need to be fully charged; a partial charge is better.
     Chargers use different methods for “ready” indication. The light signal may not always indicate a full charge.
     Discontinue using charger and/or battery if the battery gets excessively warm.
     Before prolonged storage, apply some charge to bring the pack to about half charge.
     This reference is from I think Apple is right in doing this,  as few people are aware of the dangers of Lithium Ion. Note LIne 2 of “the guidelines”  the ion in all lithium batteries does not “create energy” in the traditional sense but rather the ion molecules move in channels between diode and cathode. Overcharging overheats the lithium which causes it to expel gasses and thus lose its ability for the ion to travel correctly back and forth(charge/discharge). I have seen motorola cellphone batteries so swollen from overcharging that they would pop the back off the cellphone. A cool lithium battery is a happy lithium battery.

  • Mister Hedge

    They do this so that the lithium ion battery doesn’t overload and become potentially dangerous. It charges very rapidly until that last little bit, then it slows down. If we had to wait until that final trickle was over to unplug it, people would surely complain.

    The resulting battery loss is minimal.

    Without that slow down at the end, I’m sure that the battery would become unstable. We’ve all heard the horror stories of exploding MP3 players and laptops.

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  • Rafael Gamboa

    I can’t believe this is an article. For you idiots: ALL LITHIUM ION BATTERIES LIE TO YOU. It’s not like Apple’s the only one doing this, you morons.

  • Sky Gray

    I think those fools don’t realize you have to calibrate it by doing a full charge then emptying it to zero, then recharging to full.  This is the case for macbooks, macbook pros, ipod, iphones, ipads, etc.   Calibrate it and i bet it won’t have this “flawed algorithm” issue.


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  • David Zimmerman

    Let’s just go back to the days where we didn’t have a percentage indicator on our device’s battery, and the only notice we got that the batter was low was when the symbol had 1 battery bar instead of 3.

  • jmvane15

    I find that my ios 5 ipod never reveals it’s true battery life.  When it gets low, it goes from under 20% to like halfway a minute later.  But oh well, what can I do.  

  • Cold_dead_fingers

    When the iPad reaches 100% battery, the device stop charging and sheds some battery. You used to have to unplug cellphones once they reached their capacity because continuous charging will degrade the battery life. Apple really has little to do with the statement; just look at the science of battery technology.

  • Cold_dead_fingers

    There’s a setting for that :D

  • FrankTanghare

    Aw, you guys are so cute catching up.  But like someone earlier said, this isn’t and Apple problem, but a chatactaritic of working with LI-ION batteries. All of them.

    ” It’s best to leave it charging overnight to get the maximum runtime the next day.”

    Last year, ASUS Transformer burnt out it’s charger doing this.  At first I was trying to buy a replacement charger and none were good enough.  Eventually I learned that normal USB cords are good to 5 volts.  My ASUS required 15.  So it needs a bigger pack and cord to handle the charge.  I had to buy an OEM charger, but since I did I haven’t had any problems.  I remember one post saying something to the effect of if the cord were any thinner it would just be a heating coil.  lol.

    I DO leave it plugged in overnight sometime, but not longer than 8 hours.  I’ll unplug it first thing in the am.

  • lotherius

    Not defending the broken battery meter here, but there is a logic behind what they do other than “battery safety”, though it does stem from that.

    When a battery reaches (true) 100%, the charging circuit has to turn off to avoid damaging the battery. However, as soon as the charging turns off, the battery will begin to drain. If the charger kicks back in the second it drops back down to (true) 99% repeatedly, if the device is left plugged in for an extended time, then over the life of the device, the battery will wear out much more quickly as “topping off” like this actually causes more battery wear.

    The solution is to allow the battery to drain several percent in the ‘off charger’ mode, before the circuit kicks back in and starts charging again. Any decent phone/tablet does this today.

    Unfortunately, if battery meters report a TRUE percentage, this causes a less than optimal user experience in some eyes… Wouldn’t you be upset if your device had been on the charger ALL NIGHT, and you happened to unplug it during an ‘off charger cycle’, and it only had 97% or battery? Some phones actually do that.. Some report 100% (lie) while on-charger and immediately drop to 95% to 97% (true) when unplugged. What happens is users get frustrated that they can’t get a “full charge” and start “topping up” by unplugging/replugging their device to force the charge on mode (which wears the battery faster) or they complain to the manufactur/carrier about a faulty battery (which is not the case).

    Apple’s solution is the ‘best’ for ‘user experience’ in the sense that, they hide the off-on charging cycle from the user. It provides the peace of mind that you got a “full charge” while at the same time, protecting the battery. Power users would prefer the more accurate information, that is, the true charge level. However, when has Apple catered to power users, especially in a case like this where doing so could create confusion?