It should be intuitively obvious that converting electric power into a magnetic field […] is going to be less efficient
Ignoring sarcasm, it’s not intuitive and talking about eddy currents is probably not helpful to anyone who doesn’t feel that it is. People worked and argued about conservation and transformation of energy for hundreds of years before it was well understood. It’s easy to learn the basics, but at least when I was in school it wasn’t part of the biology course which is the only science course that most people ever take.
For anyone who hasn’t had the pleasure of a good physics course, the 4 Laws of thermodynamics can be easily remembered:
1 You can’t win
2 You can’t even break even
3 Except on a very cold day
4 But it can’t get that cold
(the fourth law is also called the zeroth law because though it was characterized last, it’s logically first. But there was already a First Law…)
Translation:
1 You can’t create energy
2 You can transform it from one form to another, but some will always be lost
3 Except at absolute zero (where all molecular/atomic motion stops completely)
4 While you can approach absolute zero as close as you want (given large enough resources), you can never reach it
And yes, ignoring subtleties of battery charging is the way to go. Life’s too short to worry about it.
That’s what I decided to do. My wireless charging stations are convenient. I have AppleCare+. Let Apple worry about it when it comes time to change the battery.
I wasn’t the one bringing physics into this. But I’m not being sarcastic that it should be obvious that any time you convert any kind of energy to a different kind, there is going to be a loss. That loss may small or large, but it has to exist. So a charging technology that requires two conversions (to and from magnetic) can not possibly be more efficient than one that doesn’t have them and is otherwise identical.
It’s obvious that two conversions cannot be more efficient. It’s not obvious that a lesser efficient charging feature would hurt the battery more because it’s not clear that the battery even knows where it’s getting it’s charge from. It might only have one connection point internally. I don’t know.
The optimized charging feature probably can’t work as well for you doing multiple short charging sessions per day. I never put mine on the wireless charger during the day unless the battery is less than 30% and I still need to use it for awhile. I only charge with a wire in my car when using navigation or on long trips, and only because I don’t have wireless charging there. Otherwise I just put it on my wireless charger at night while I’m asleep. I’m on a 13 pro that I got on day 1 of availability and my battery health is at 92% now.
I was excited to get my first car with wireless charging, but have to say in practice, I haven’t found it very useful on trips such as you describe. Running CarPlay with music and navigation, the phone’s battery will stay about even with where it started if it’s in the wireless charging tray. If I plug it in to the car’s USB-C jack, it will charge over time no matter what’s running.
As I said earlier, I’ve rarely wireless charged my 13 Pro, and at one year it’s still at 100% health. Every data point I see if people who do a lot of wireless charging keeps convincing me that wired charging is the way to go.
However, all that said, and slightly off-topic: for the second time in the last few days, I had my phone plugged in overnight and the battery did not charge. Here is last night’s graph:
I’m not sure if this is a 16.0.2 bug (it’s only happened since I installed that update), or something with my travel charger, but I’ve used the charger and cable many times since I bought the 13 Pro, and 14 times earlier this month with no issue at all. The phone definitely knows that it’s plugged in (as you can see from the circled part of the graph), and I get the haptic feedback and the green icon when I plug in, and the phone even discharges. I did restart the phone after the last time it happened, so restarting didn’t fix the issue. Strange.
Because you probably want 100% battery charge when you start using your phone for the day? Providing the battery with the longest lifespan conflicts with give you a charge that will serve you best for the day.
That’s why Apple’s battery optimization uses machine learning to keep the iPhone at or below 80% until such time as it believes it can charge to 100% right before you take it off the charger.
I suppose that for verification, it would need to have learned your regular sleep schedule (go to bed at 11 PM, get up at 7 AM, for instance) and then you’d have to check it at say 3 AM, when it would have had plenty of time to charge to 100% but in theory should be holding around 80%. In theory, the battery life graph should reveal that too, though I’ll acknowledge that it doesn’t on my iPhone 14 Pro, but it’s perhaps too new (and I just packed up the iPhone 13 Pro to send back).
It’s a machine-learning black box, so there’s no way to know when it has trained sufficiently or if your schedule is regular enough for it to work.
I think as mentioned before, optimized charging is designed for people who have a regular once-a-day, same time every day, in a stable location, charging habit when the phone is well below 80%. Im home last night from travel, but last night I didn’t get optimized charging - based on what I’ve seen in the past, you need to be in the same location for a few days before it kicks in again.
Unlike the Mac, it is not designed to charge and hold to 80% on demand - it’s designed to charge and hold to 80 until a short time before you usually unplug the phone, and then it charges to 100% during that time (e.g., two hours before you usually wake up and unplug if you charge overnight). It’s not designed to work if your charging habit is irregular, or charge all day while the phone sits next to you, etc. For me it works, as I almost always charge overnight while I sleep and rarely at other times during the day - but it will kick in overnight if I do a top-up charge while I am doing a short drive in the car at some point during the day.
Or if it’s actually capable of doing what somebody like @doug2 needs in the first place. Some usage patterns can be very different. As you allude to, depending on the amount of effort hat went into this, unless you have a regular schedule, there might be very little magic here. Apple can certainly do ML right (see their comp imaging), but we have no idea how much depth was put into this system. As somebody who makes a living in ML, let me just say that these days companies are quick to advertise ML/AI as their magical solution. But often what is actually delivered is far less fancy, not seldom, resulting in more emphasis on artificial than actual intelligence.
I think iPhone optimized charging is extremely conservative for the reason that Apple doesn’t want customers who plug in expecting to fully charge their phone from, say, 20% and find that the phone has been sitting at 80% when most people would want it to go to fully charged in that scenario. It’s really designed for users who regularly plug in at bedtime and leave it plugged in until they wake.
Sorry if someone has already addressed this, but my understanding is that whenever the OS is updated, the battery heath is re-evaluated and provides a new estimate at that time. This might explain why the percentage would remain constant for awhile and then suddenly drop.
It’s not usually worth it to be too concerned about the specific battery health number. It can fluctuate up and down, though obviously the trend is downward over time. I’d put the difference between 98% and 92% as pretty close to statistical noise. Multiple factors can impact it, even temperature, if I recall correctly. I’d only get concerned if there is a rapid, sustained decline over 15% or more over a few weeks or a sudden, catastrophic drop.
You might be interested in the paid version of the Mac coconutBattery app, which does a nice job of tracking battery health on Mac and iOS devices over time.
In fact, here’s my battery last night. I circled the time when it was plugged in. Prior to ios16, the time that the phone was being held at 80% had a light green background, so that’s changed with ios16.
