With optimized battery charging, the phone uses machine learning to understand when you most often wake up in the morning. When it is working, it will do a normal charge to 80%, hold it until an hour or two before it thinks you normally wake, and then complete the rest of the charge. If you look at the battery graph when you wake you will see this.
The last 10 to 20 percent of a charge are what stresses a battery most, and holding at 80 with a trickle charge rather than trickling at a a full charge should stress the battery less long-term.
I should also note that fast charging with faster than a 1 or 2 watt charger will fast charge only to a certain percentage (I’m not sure what the real amount is, but it could be 80%, it could be lower) and then the phone slows the charge to a lower wattage - again, to put less stress on the battery. This is one of the reasons why I think that using fast chargers really doesn’t have a major effect on long-term battery health compared with slower charging.
Basically, anything you can do to reduce heat will help your battery’s longevity, so slow charging using a lightning cable will be much better than fast charging or inductive charging.
Also, I’ve heard that - depending on your daily power needs - it’s better to charge up to about 80% and not drain your battery all the way down. Reducing the “pressure” in the battery keeps it much healthier.
My iPhone 11 Pro Max’s battery health is hovering around 99% after almost a year of use, and though I don’t strictly follow the guidelines I’ve given I do try to follow them when it’s convenient.
Is it better to charge to 80% and drain to 50% repeatedly than it is to charge to 100% and drain to 70% repeatedly? Certainly it’s much easier to charge to 100% than to 80%; would it be worth the effort to avoid charging to 100%?
Is that another way of asking if charging from 70% to 100% generates more heat than charging from 50% to 80%?
As I understand it, Li-ion battery packs are stressed more at close to full charge than they are at less than full charge, so experts suggest that charging up to 80% and small discharges and charge cycles should be better for long-term battery health than charging fully and discharging to and charging from 70. I’m not sure that anybody has quantified what the difference is for iPhones; whether the long-term battery health would be worth the hassle of paying such close attention.
Then again, I’ve heard of people who almost always use their phones when they are plugged in and after a couple of years of this they still had full battery health.
My feeling is that I’m just going to use my phone and charge it when it’s convenient to me. I have a 31 month old iPhone X at 91% health so I feel that I’ve done alright.
Yeah, two big factors are lifestyle and battery capacity of your device.
I’m retired now, and my iPhone 11 Pro Max has scads of battery life so I charge the device when it gets below 50% (and I notice), and don’t need 100% charge to get through my day.
I’m pretty much always near a desktop, and when I’m out it’s just to shop and I don’t spend lots of time in stores so I do plug in to the car for navigation and CarPlay so it gets charged there too.
If you have a device with less capacity and are away from chargers for long periods of time, you may have less choice in the matter.
I’m most disappointed to learn that the “Optimized” charging I had heard about first a few weeks ago is actually not optimized. I turned it on assuming (never assume!) that it would optimize the life of my battery by stopping the charge at 80%.
Perhaps I can train myself to, before stumbling toward the bathroom in the morning, first unplug the charger, to stop the so-called “optimized” from pushing on to 100%.
That’s not what optimized battery charging does. It is not supposed to stop charging at 80% or at any other percentage.
The purpose is to use some machine learning to determine when it can reasonably expect to be connected to a charger for an extended amount of time (e.g. at night at home, or in your office), disabling the “fast charge” mode in those situations:
The idea is that in these situations, there is enough time for a slow charge to fully charge the device, so there is no need for fast charging. But that’s all it does.
True, but there are some windows laptops that allow the battery to stop charging at 80% for people who mostly plug in and only occasionally use the device off power, in order to increase the longevity of the battery pack. I can see why Apple doesn’t want this setting on the iPhone - the idea is to allow people to have a full battery when they do a long term charge - but there may be some people who would benefit from this behavior. Still, there is such a thing as too many options, and the people who would want and benefit from this probably aren’t worth adding the option to settings.
Optimized charging does not change the rate of charging, it simply holds the battery at 80% until it’s necessary to finish charging to 100% by the usual time you remove it from the charger.
Tesla allows drivers of their electric cars to specify the max charge and they recommend 80%-90% for daily use. On those days when a full charge is desired, bump it up to 100% and plug it in. After a day or two, if you forget to set it back to the “daily max” setting, the car will remind you to lower it.
Seems like an easy thing for Apple to do if they wanted to. If you don’t burn up your battery each day, why not reduce the stress on the batteries by allowing you to specify a lower daily charge?
For quite a while now I’ve been reading that Apple and Tesla have each been on track to begin making their own batteries in the not distant future. Elon Musk has been very vocal about it:
Apple isn’t as far along in the game, but they usually keep their mouths shut until the end result is ready for debut:
Well, when a replacement battery for your “mobile device” costs $30,000 then you really, really want it to last 10-15 years at least. I limit my charge to 70% most days and charge with a slow (7,000 watt) charger at home. I only charge above 90% with fast (150,000 watt) chargers when I’m traveling.
When it comes to phones, though, I really think most people would be better served by just plugging it in when they can and not stressing about it. I’ve been working with batteries since the 1970s and obsess a bit about longevity (I have an iPhone 6s Plus in daily heavy use that still has 88% maximum capacity) but, seriously, I’d be happier if I just let it go and replaced the battery or the phone every couple of years.
That’s my understanding … though I’ve never measured anything.
My practice is to charge it when it’s below 50% and disconnect it when it reaches at least 80%.
My wife will be replacing her iPhone 7 which has something like 80% battery health with my 11 Pro Max, but she’s always running around with the 7 connected to a battery brick - I gave my daughter and wife battery bricks last Christmas.
My daughter’s getting a 12 128GB, and I’m ordering a 12 Pro Max when they become available.
I want some carrier flexibility, and I’m frankly a bit sick of 7 generation phones and their flakey batteries. If I’m reading it right, I should save about $45/month switching to T-Mobile from AT&T.
Of course, even if that’s true there is no payback from the cost savings - it would probably take 56 months to make up the cost of the new phones from cheaper plans even if we ignore the present value of the 11 Pro Max - but there should be a definite quality-of-life improvement over those rickety old phones.
Hopefully now that we know a bit more about battery health we can preserve it more effectively.
Certainly, iPhone batteries are much cheaper than Tesla batteries but there’s no reason Apple couldn’t take some stress off the battery by allowing users to set a lower charge limit, if they want. I never use more than about 60% to 70% of my phone’s battery in a day, so there’s no reason to charge it to 100% each night if the lower limit would extend its life.
Apple was never too big on giving users a ton of options. I bet they figure at $69 for a new battery on a device that costs on the order of ~$1k they don’t need to offer settings for exactly how and when to charge.
Just use it till the battery’s toast and then get it replaced. I doubt they’d put it exactly that way though, doesn’t sound terribly green to me. Still, I’m pretty sure that’s essentially how they see it.
Personally, I’m OK with that. The problem I have with swapping a battery after 2 years of use or so is not the $69, it’s that I have to get one of these super rare appointments in the middle of my work day, and then it’s not at all clear that they’ll just quickly do the swap in the back and return my phone 20 min later so I can get back to work. There are these great stories of people being told they need to leave it over night and stuff.
They bricked my phone last year replacing the battery. That took hours to get the new phone going and a second trip to the store to try and wipe the original phone (it was completely dead). And getting appointments is not as easy as it was a few years ago (probably worse now due to covid)
The 11 Pros came with an 18w power adaptor - to fast charge using MagSafe you’re supposed to use a 20w PD 3.0 charger. As an ode to the iPhone 12, they’ve reduced the 20w Apple charger from $29 to $19 - a steal at Apple prices.
Fast charging on the iPhone 12 requires a 9v 2.22a power profile, something (according to AppleInsider) all 20w PD 3.0 chargers have but higher wattage PD 3.0 chargers may not.
I avoid fast and inductive charging because they heat the battery, so I use a lower powered charger - in my office I’m currently using a 10 port USB powered hub which delivers 5v 2.1a per port and a lightning cable.
Technically that’s a low end fast charger - isn’t the old Apple power adaptor 5w? - but I don’t want to sacrifice a precious AC plug for a little one-use charging brick.
On my nightstand I do do Qi charging my my phone’s low, but that charger is just so convenient that I’ll use it when either my phone or watch or AirPod’s charge is low. It’s a $29 charger I found on Amazon and unlike Apple’s product it’s actually something that exists.
I bought a $9 Aukey 18w USB-C tiny charger on Amazon and have been using it with Magsafe and iPhone 12 Pro. I suppose it’s not charging at the very max, but I don’t care. It’s really fast. I use it to top off my iphone during the day, so sometimes if it’s 50% by evening I might put it on the puck to charge it so I don’t run out later that night (depending on what I’ll be doing). I put it on there for 30 minutes and it’s up over 80%.
By comparison, my old iPhone 11 Pro on a Qi charger would take two+ hours to go from 50-90%. I put it on the charger multiple times a day to keep it charged. It was also really finicky and wouldn’t charge two out of ten times, requiring I fiddle with it until I got the green charging icon.
With Magsafe, I am only topping off the phone only occasionally (not every day) and for as little as 15 minutes. It works great.
I have the same one for my old iPad and it’s great. I plan to use it for my new 12 mini too. But straight Lightning, no MagSafe here.
My wife preferred getting a 30W RAVPower so she can use the same charger to power her new MBA (fingers crossed for AS release in two weeks) and her new 12 mini. She has no desire for a MagSafe either.
In the car we definitely plan on installing a mount with MagSafe. There’s a nice Anker ual USB-C 36W adapter that should work just fine there. https://www.amazon.com/gp/product/B07RL2N8YY
