The iPad 3's battery algorithm is busted, here's why

The iPad 3's battery algorithm is busted, here's why

Summary: If you unplug your iPad 3 as soon as the battery indicator says "100%" you're missing out on as much as 1.2 hours (10 percent) of additional run time. When's Apple going to fix this?

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TOPICS: Hardware, iPad, Mobility
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The iPad 3's battery algorithm is busted, here's why - Jason O'GradyOn Friday I noted that the iPad 3 battery continues charging even after the menu bar icon reports that it’s “100%” full. In fact, the iPad 3 isn’t fully charged until 2 hours and 10 minutes after it says so.

Ray Soneira, President of DisplayMate Technologies Corporation discovered that the iPad 3's running time based on a fully charged battery is 11.6 hours but that its running time based on the 100% battery indicator is only 10.4 hours - or a net loss of 1.2 hours, or around 10 percent, if you unplug it when the battery gauge in the upper right claims that it's reached "100%."

So why does Apple's battery algorithm do this?

ZDNET's own Adrian Kingsley-Hughes claims that iPad 3 battery meter is behaving just as it should and that Apple displays the 100 percent charge indicator at a lower capacity, (around 97 percent) to keep the battery "safe and healthy." He claims that Apple has always done this but that it's more noticeable in the iPad 3 because its battery is 70 percent larger:

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.

In his iPad Display Technology Shootout Soneira notes that it takes over 5.5 hours to charge the iPad 3 when it is fully discharged (when off or in sleep mode.) If you try recharging while using the iPad 3 it can take up to 20 hours to charge with the display is set to maximum brightness.

The wrinkle is that when the iPad 3 battery indicator first says "100%," the battery is actually only 90% charged and you get 1.2 hours less running time. However if you recharge your iPad 3 unattended (and off or in sleep mode), especially overnight, you will get the necessary extra charging time to achieve its maximum running time.

Oddly according to Jon Fortt of CNBC (video) "Apple is saying... if you charge it more than [when the battery indicator reads 100%], you could actually harm the longevity of the battery."

Personally, I think that the iPad 3 battery indicator should accurately display how much charge it has, so that people don't unplug it prematurely and miss out on 10 percent more potential run time. I bet that it gets fixed in a software update.

Topics: Hardware, iPad, Mobility

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43 comments
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  • Or

    Well, if Apple says it should be unplugged when the indicator reads 100% THEN (and only then) there is a bigger problem. First the battery life indication is wrong, at should be measured from 100% indicated, AND it should stop charging at that point.

    Can you get an answer from Apple? I think most people will charge the iPad and pay no attention to this indicator (probably overnight).
    jeremychappell
    • Battery indication is wrong; and ever-long charging does not hurt ...

      ... contemporary batteries (Apple did not say opposite, contrary to what unsourced CNBC information).

      iPad also displays Wi-Fi strength wrongly: at times it shows zero bars, and connection should not work, while it is quite alive and well.

      So these two bugs has to be fixed.
      DDERSSS
    • I agree

      "I think most people will charge the iPad and pay no attention to this indicator (probably overnight)."

      That is how I charge both my iDevices. If it turns out that I should be waiting up all night in order to unplug them the instant they say 100% then I really wish Apple had said that up front. Now I find out that I've been damaging the batteries in my iPhone and iPad?
      toddbottom3
      • Not at all worried

        I agree. I have never worried about the 100%. It's the 0% that I worry about.
        spikedstrider
      • I agree

        I have always left my iPad 1 plugged overnight and it has no battery problems. I do the same for my iPhone and now the new iPad.

        Batteries these days stop charging once they are fully charged. Otherwise my iPhone and iPad 1 batteries would be dead now since I plug them in when I go to bed each night.
        Apchouston
  • Worth it?

    Is the new screen really worth all this battery hoopla? I have not seen the new display with my own eyes yet but am satified with my iPad 2 display.

    If you could have an iPad 2 with the new battery and get all that extra usage would you take it over the iPad 3's retina display?
    clcrockett
    • It is to me. I bought the new iPad specifically for the Retina display

      and don't regret it.
      baggins_z
    • Your last question is a good one.

      Your premise implies an iPad 2 with the weight and physical form factor of an iPad 3 having the electronics of an iPad 2 but using the iPad 3 battery design. This hypothetical tablet would yield a device with over 20 hours of battery charge duration. For most enterprise markets such a tablet design would be ideal.

      However, that retina display is a game changer, as they say. Plus, the iPad 3 has additional electronic improvements such as 4G and a better camera.

      It's a tough, interesting choice but I would choose the iPad 3 over this hypothetical tablet design for my personal use.
      kenosha77a
    • Here's the thing

      When you first see it alone, you are like, wow! That is a really nice display...

      When you see it beside an iPad 2 or a Transformer Prime, The difference isn't as glaring unless you are pixel peeping.

      For me, I can say, with Movies running HD next to the Sony Tablet S, the difference wasn't hugely evident as the screen size minimizes the impact. Of course, reading books I could see the difference in the text but, I have been reading books at 720P for some time now so, it is not a deal breaker.

      Overall, yes the screen is very nice and yes the size does limit its effectiveness... I do not believe the screen will make the difference to everyone buy there is no doubting it is an excellent screen.
      slickjim
      • It isn't a game changer and it won't make you more productive

        I remember when I watched my first football game in HD and wow, I was impressed. Compared to SD, there is no doubt that HD is more pleasurable, more entertaining. The question is: was HD a game changer? Did it change the way we watched TV? The answer is a very easy one: no. TiVO was a game changer. That changed the way we watched TV.

        The exact can be said of the new iPad's display. Is it nice? Sure, as nice as HD is compared to SD. The resolution on my iPad 2 is passable. It gets the job done. But would more pixels change the way I used the iPad? No. It would not. This high resolution display is very nice but it isn't a game changer. It isn't revolutionary. It is nice and there is nothing wrong with that so why make it out to be something it simply isn't?
        toddbottom3
      • The difference is big and obvious ...

        ... when you compare an iPad 3 with an iPad 2 side by side. The improved resolution is absolutely "glaring" as you say (which is a weird choice of metaphor to use about a device that actually can suffer from glare).

        There are enough negatives (increased thickness and weight, heat problems, battery problems, etc.) that give me the impression that iPad 3 was not fully ready for launch. Something inside me says Steve Jobs would have sent it back to the designers & engineers over and over and over again until is was the same thickness or less, the same weight or less, etc.
        RationalGuy
    • No I'll take the retina display

      If it's possible to put the 42.5 watt hour battery in the iPad 2, I'll still take the new iPad. My eyesight is to the point where I wear bifocals and I upgraded from the iPad 1 to the new iPad and the difference on just the display is worth it for me. I'm not a big gamer but I do read a lot so the extra resolution is great for my eyes.

      Owners on the iPad 2 might see much of a speed bump on the new iPad and don't necessarily need to upgrade unless you really want the retina display.
      Apchouston
      • RE: nitpicking

        Increased thickness? It fits in every single ipad2 case. That means its a nonissue. Increased weight? Its because it got a bigger battery
        and what heat problem? It's warm, but when the screen is better than your HDTV and desktop monitor you might expect that's hard to avoid.
        yenic
    • Wrong question

      "Is the new screen really worth all this battery hoopla?"
      Everything's worth for an iFan for not having to admit that he paid 2x times more for something that's not only sub par with concurrent rival devices, but also that it has even more bugs and design flaws than the previous iDevice, whose annoyances he hoped to get rid of in the first place when he bought the successor.

      If the iFans were ever to admit to the flaws of their iDevices or that the new iDevice X+1's supposed advantages don't actually outweight the drawbacks and new flaws, that would also mean admitting that once again they were stupid for having been tricked into buying another overpriced, yet seriously flawed device.

      And of course, who would freely admit that he's stupid - even then when he obviously is?
      ff2
  • So Apple can't come up with a way

    that tells the charger to quit charging at a certain point? That would protect the longevity of the battery.

    Instead they want you to keep an eye on the charge time manually, or wake up in the middle of the night to unplug it?

    Sounds like an excuse, as how could it continue to charge past 100% unless there is some issue?
    William Farrel
    • Check your facts you are (unsurprisingly) VERY wrong

      Contrary to what CNBC says, Apple has never stated that you need to watch the charge time manually. The research that first noted the iPad continuing to charge after the meter reaches 100% also notes that the charging rate diminishes and stops as the battery capacity is met.

      http://www.apple.com/batteries/ipad.html
      http://manuals.info.apple.com/en_US/ipad_user_guide.pdf
      use_what_works_4_U
      • Ahh...

        Well, then this behaviour sounds perfectly correct then.

        As long as, Apple are not expecting people to watch the indicator and unplug the device when it reaches 100% - then that's okay. The whole 100% notion is rather muddle-headed anyway. You don't actually charge the battery to 100% - that would damage it.

        My original iPad would often charge to "99%" then never get any further, the next day it would charge to "100%" (I've even seen it "stick" at 98%). Never seemed to make a jot of difference to the performance.
        jeremychappell
  • The story isn't what's comical

    What is comical is the way the Apple fanbois go nuts in their attempts to defend everything Apple does. Apple doesn't need to be defended against this. There is a problem, it will be fixed. Quite frankly, Apple fanbois should do everything they can to bring this to the attention of Apple so they will fix it. Apple has been known to not fix things unless people make a fuss. Apple fanbois are the ones holding back improvements to their iDevices. And mine.
    toddbottom3
    • No, you're what's comical too

      Something a simple software update will fix in the long run.

      Funny how Apple fixes issues in a short matter of time, Microsoft lets holes in software stay open for YEARS.
      http404
    • What's even worse is

      The Microsoft fanboys like you, that Lie about owning Apple products, just to disparage them. Like when you claimed to buy a MacBook Pro, only to wipe the Hard drive and install Windows 7 on it. And how much you felt that Evil Apple was over charging fir an update to Bootcamp, because you only run Windows 7 on your fictitious MacBook Pro
      Jumpin Jack Flash