iPhone X and iPhone 8/Plus: Tests suggest wireless charging will wear out the battery faster than cable charging

“As much as I love the convenience of wireless charging, I’m switching back to a cable,” Adrian Kingsley-Hughes reports for ZDNet. “Back in January, I became suspicious that regularly using wireless charging wouldn’t be good for the long-term health of my iPhone’s battery.”

“According to Apple, the battery ‘is designed to retain up to 80 percent of its original capacity at 500 complete charge cycles,’ and beyond that, the battery is considered worn and heading toward end-of-life,” Kingsley-Hughes reports. “Realistically I’m expecting to hit the 500 mark in less than 18 months if I don’t change my habits. Previously I would have expected an iPhone to make it closer to the 36-month/three-year mark before hitting the 500 recharge cycle (working out as a full recharge every couple of days or so).”

“The issue is that when the iPhone is being charged using a cable, the phone is being powered by the cord (there is some load on the battery, but it’s minimal), but when using wireless charging, the battery is what’s powering the iPhone, with the wireless charger only being used to top up the battery,” Kingsley-Hughes reports. “This means that by switching from a cable to a wireless charger, my battery isn’t getting a break, and in turn, this is making me go through recharge cycles at an even faster rate.”

Read more in the full article here.

MacDailyNews Take: We all have iPhone X units here and we charge them with cables, not wireless chargers – mainly because we’re waiting for Apple’s AirPower, but also because after a decade+ of iPhones, we have our routines and they don’t involve charging pads (that are, by the way, cabled themselves anyway).

27 Comments

  1. I tend to disagree.

    While I don’t dispute (or necessarily agree with) the logic of the article, I’d make another point which I believe reverses the conclusion when all things are considered

    I’m currently using wireless charging most of the time, which means that every time I put my phone down on my desk or table, I actually pop it onto a wireless charging cradle. That’s because it takes zero extra effort to do that, as opposed to laying on that table.

    Before wireless charging, I ONLY charged the device when the battery got low, because plugging it into the cable or cradle required just enough effort that I never ever felt like bothering

    Every serious, reliable, in depth source says that your battery will have much longer life if you always recharge before it begins to get low, and that you’ll absolutely maximize its health over time if you constantly top it off.

    Now people who will always use their phone with it plugged into a cable, might benefit from wired charging vs wireless (assuming the article is right about their primary point of the phone being able to run off the cord primarily, which may not be right). But for people like myself, cordless charging will greatly extend your battery’s long term life

    1. Similarly I was told that you should charge before it get’s too low, but was also told never to charge it completely to 100% to extend the life of the battery.

      1. That point about never fully charging is true in theory, but from what I’ve heard, is not applicable to apple devices, which always go into into a cycle of mild discharging and recharging as they approach max charge. This final process of apple’s is said to keep the batteries very finely tuned.

        1. I would think even that mild charge/discharge adds up over time. I guess in the end it’s up to the individual’s convenience as to what best suits them. 😀

          Personally I near top off my charge once before going to bed and once after lunch when restarting work.

          1. What I meant about keeping the batteries very finely tuned is this:

            I’ve heard that Apple’s discharge and charge cycling actually improves long time battery life and helps to condition the batteries.

            Apple has stated that its fine to keep its devices sitting in chargers full time, which seems to support this claim.

      2. Apple’s battery charging system manages the charging quite well and maximizes the charging cycles without the USER ever having to worry about such picayune stuff as watching the percentage of charge to manage it himself.

        Do you really think Apple would ignore such a thing to put the onus on the user?

        Apple handles such charging inside the iPhone. 100% charging will not damage your iPhone’s battery. Charging stops when the battery has reached the optimum charge. The software will not allow it to overcharge.

    2. I think you are absolutely correct. There is no logic in his statement that wireless charger forces the phone to run on battery. There is no reason for the internal charging circuitry to know how the charging power is being supplied (via induction, or via Lightning connector). If there is enough current to charge the battery as well as power the phone (whether by induction or via cable), the phone will get whatever power is needed and the rest will charge the battery.

      I did some googling and some research, and it is clear to me that regardless of how phone is charged, the current first goes to power the phone, and whatever is left is then used to charge the battery. This is why you could always take out your battery (on a non-iPhone device) and still use the phone normally (as long as the charge provides enough power). There may be situations where the phone may try to pull more power than what the charger can provide (if you’re playing a demanding, CPU- and GPU-intensive game), and if there isn’t enough power, and battery is out, the phone will shut off (or throttle down the CPU/GPU, if the OS is smart enough).

      So, no, the article is not right. Wireless charging does not force the phone to run on battery; it continues to run on whatever current the charger is providing.

    3. Adrian Kingsley-Hughes’ research turns out to be comparing his charging cycles on an App he has installed on both of his two iPhones, an X and an SE and seeing that one has used more charge cycles in six months than the other.

      That is NOT research. I suggest that the old adage that “the plural of anecdote is not data” holds true here. What I see is that it is much easier to place his wireless charging iPhone X into it’s wireless cradle than it is to find a charging cable and plug in his iPhone SE when either one is idle.

      The fact is that if one were to charge each iPhone nightly, one would expect to see approximately 182 charge cycles in six months. Kingsley-Hughes saw less than that for each iPhone. he worried he’d go through the 80%/500 design parameter battery life before 18 months had passed for his iPhone X. . . but the fact is that with a nightly charge routine, something each of us with phones routinely do, 18 months represents about 548 expected charge cycles.

      If one wants to extend the battery, one should discipline oneself to only charge one’s iPhone every other night.

      The fact is this is NOT what it seems at all. ALL lithium-Ion batteries do exactly the same thing. It’s the nature of the technology. Also, the claim that Kingsley-Hughes made that by using a wired charger the iPhone was somehow using the AC current to operate and “give the battery a rest” is bogus. There is no switch inside the iPhone that switches out the battery during charging which puts the iPhone onto AC current. You can see this for yourself by observing that it takes longer to reach a full charge while watching a movie while charging than if you just let it charge. The battery is still discharging while charging to power the iPhone to display the movie.

      Adrian Kingsley-Hughes is a writer, not a researcher. . . and does not understand at all what he was seeing.

  2. If I still own an iPhone after two years I expect to have to replace the battery, no matter how its charged.

    Smart phones have become integral with our way of life. Expecting a battery that is used as much as a smart phone does today, and still have a viable battery two years after purchase (new) is not realistic.

  3. I have had little interest in wireless charging as I (like MDN) have a “ritual” where I plug everything in before I got to bed. As long as my phone makes it all day, which has not been a problem since the 6s+, it works great. However I recently got upgraded to a Cadillac Escalade while traveling and it had built in wireless charging on the “console”. I put my phone down and was surprised when it just started charging. I HATE fumbling for my cord in the car. My next car purchase WILL have wireless as an option.

  4. I suspect that if the phone were being used *on* the charger, it wouldn’t make a difference at all. However, if you remove the phone from the charger, use it (off battery power), then put it back on the charger, that *might* make a small difference.

    OTOH, if you’re using your phone so much that this will really make a difference in battery lifetime, perhaps you might want to consider some of your life choices. Hell, I can’t remember the last time I had to charge my phone during the day because I was using my phone so much. Granted, I’m an old fogey and I don’t live on my phone 24/7, but if you’re wearing out your battery faster than two years (expected lifetime of a li-ion battery), there’s something wrong with your life.

  5. I have a wireless charger on my dresser. I put my phone there at night and pick it up in the morning. Couldn’t be more convenient and can’t imagine going back to a cable. I don’t need to charge any other time.

  6. Something doesn’t make sense here. Exactly why would a phone run off the charger when charging with a cable, and not when charging with an induction charger? In both cases, a steady current is being supplied to the charging circuitry, which sends the appropriate amount of it to the battery, and the rest is available to the phone. How that current made its way to the charging circuitry cannot be relevant; voltage is voltage, amperes are amperes.

    I think the only reason the writer of the original article is worried is the high number of charging cycles that is showing up on that CoconutBattery app that measures battery health.

    And the only reason that I can think of why that number would be noticeably higher when charging wirelessly than when charging via cable is if he frequently takes calls while charging the phone. If he leaves it connected to the cable, the charging process isn’t interrupted, but if he picks it up from the charging pad, that ends a charging cycle, and putting it down after the phone call starts a new cycle. Five calls per day equals five more charging cycles, vs. just one (with a cable).

    I can’t imagine this would have any meaningful effect on the actual battery health, and that the 500-cycle “magic number” that Apple cites is an average number based on typical usage patterns (one, perhaps two, maximum three charging cycles per day; one overnight, when phone is plugged in before going to bed, another during the day, in the office, or in the car, if the battery needs it).

    I would say, if you like wireless charging, charge away. And if you work a desk job, having the phone on the wireless charger, rather than disconnected from the charger, will most certainly extent its battery. Rather than running on battery all day, it will be running on that wireless charger, switching to battery only when you pick it up to use it.

    1. I’m hesitant to say that the same charging circuitry is used for both corded and wireless charging. With a cord some of the ‘intelligence’ of providing the charge is in the transformer plugged into the wall. For wireless charging something similar has to be provided to regulate the charge going to the battery or overload the controller (assuming it uses the same controller).

      On a tangent line of thought, if you used a low setting on an IR heater would it charge wireless charged devices?

      1. Actually, the transformer has nothing but the transformer, some PFC circuitry (for input voltage) and a rectifier. There is no “intelligence” in there, because if there were, it would then be problematic when you plug in your lightning cable into that USB charging socket on an airplane, bus, in your laptop, or into any of those 3rd-party chargers of all kinds. Those can’t be expected to have any “intelligence” specifically designed for the iPhone in order to properly charge it.

        The only meaningful difference between various chargers boils down to two things:
        output current (500mA – 2A, or even higher)
        cleanliness of output power (voltage stability)

        Cheap, crappy chargers can output anywhere between 4 – 7V, and such huge variation can damage the phone’s charging circuitry. If the charger output is clean 5V, you can safely plug your phone into it. Probably the cleanest possible charging power can be obtained from those external charging packs, which are essentially DC batteries, which by nature provide cleanest, smoothest 5VDC output.

    2. There’s quite a lot here that doesn’t make sense. The headline refers to tests, but nowhere in the original article can I see any explanation of any actual testing other than counting the number of charge cycles and then making assumptions based on what Apple has previously said about the life of batteries.

      It’s a while since I did any serious research on rechargeable batteries, but it used to be the case that deep discharge followed by full recharging was the way to go and that frequent topping up of a mostly charged battery was not advised. The means by which the recharging is done ( cable / wireless ) shouldn’t make much difference, what makes the difference is using an iPhone until the battery is pretty empty and then fully recharging it.

      Apple usually carefully consider unexpected aspects of any technology which they deploy and if there was any prospect that wireless charging reduced battery life, I would expect them to design their systems to safeguard the battery life.

      This seems to be a scare story based on speculation and there has been no description of any meaningful testing to back up the story.

      1. Hiya. Before lithium batteries it was advised to fully discharge and recharge batteries. Now it is advised to top up frequently to keep it above say 70 percent.

        Also I heard that charging when at 100% actually stops charging until the battery reaches 96% when it will start charging again. This does age the battery a little.

        I find if I am sat down using my phone I will have it charging. I think most people charge it at night, and that is fine too.

        1. Apple’s battery management software handles all of that picayune worry about battery health for the user. You don’t have to worry about watching the percentage meter on charging. It won’t over or undercharge your battery.

          Just charge it when it gets low.

  7. Clickbait. It “may” make a difference depending on how you use it and that difference over the life of the phone “may” be so small that you never notice it.

    Throw in “not” after “may”, one or both, and it’s just as accurate either way.

  8. The question then becomes, “Does wireless charging provide the same watts as a cable with Apple’s brick?”

    I notice if I use a cheap low watt brick on my phone and use it at the same time, the battery will stay the same level and never charge. That tells me the phone is actively using all the watts that the brick can push.
    If the wireless charging is even less watts then I would expect the battery level to slowly drop when in use. I don’t think that’s happening. This story is missing something.

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