And FWIW, my iPhone 16 Pro is over a year old and is still at 100% battery health. Heck, even my Series 8 Apple Watch is at 86%, and it’s 3 years old.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
In-Depth iPhone Battery Experiment Pits Slow Charging Against Fast Charging
- Thread starter MacRumors
- Start date
- Sort by reaction score
And FWIW, my iPhone 16 Pro is over a year old and is still at 100% battery health. Heck, even my Series 8 Apple Watch is at 86%, and it’s 3 years old.
Overall cell impedance increases as a battery ages, and voltage sag is proportional to applied current. Slowing down the phones prevents huge current spikes that would sag the voltage below levels needed to run the ship, shutting down the phone…
If you typically don't need more than 80%, then it could significantly lengthen the time until you drop below 80% and then replace the battery. The experiment shows that the 30-80% iPhone dropped only 8% in the same time the 5-100% iPhone dropped 12%. Extrapolating, this might mean that if the latter drops below 80% after 3-4 years, the former might take 4-6 years with the same usage to drop below 80%. It might make the difference between having and not having to replace the battery before getting a new phone. In addition, on the occasional days where you know you'll need more than 80%, you'll have opportunity to make use of >80% for longer as well. Of course, if you get a new iPhone every other year, it makes less of a difference.
Apart from that, the 80% limit isn't 80% of the original battery capacity, it's 80% of whatever battery capacity you still have left. When you charge your phone to 100% but the battery capacity is only 90% anymore, the 100% are really only 90% of the original capacity. Similarly for the 80% charging limit.
The latter scenario gives you the option to charge to 100%, though. For example, my iPhone is plugged in probably about 75% of the day. When I am at home, it’s almost always plugged in. When I’m at work, it’s plugged in on my desk. My battery rarely gets below 60%, so I have 80% charging set. But when I am traveling, I want the full battery capacity - and I’ll set the iPhone to charge to 100% and I have nearly that full capacity because I haven’t significantly degraded my battery.
Most of these tests are comparing whether there’s a difference between charging one a day to 100% or 80%, and I agree that the data shows it’s not worth limiting to 80%. But in that scenario, the phone isn’t sitting around 100% all day - people are using it, drawing down the battery and not recharging it, bring the average battery capacity lower. But if a phone is plugged in the vast majority of the time, then it’s sitting at 100% much more than is in these tests, and that difference is going to cause a bigger impact.
I wholeheartedly agree for most people an 80% charge limit doesn’t make sense. But having the option is very nice for scenarios like mine, where the phone is powered most of the time. I’ve have had a few iPhones that by the end of my typical four year lifespan, the battery capacity was in the low 80s - and I didn’t have the option of charging to 100 when I needed to, because that was actual degradation. I wouldn’t recommend others take this approach though unless their phone are plugged in most the time like mine is.
I’ll remember that as I reach 50% charge at the end of nearly every day so I am not artificially limiting myself by just turning on a setting. /s
What is silly is to assume that everyone needs 100% of battery every day.
My XS, which has the cruddiest battery life of all phones since, is at 81% on its second battery. The official replacement was much poorer quality than the original which makes me think there’s a huge element of luck involved.
Thank you for the clarification on that!
From the tests on that channel it seems like not doing deep discharges helps more than anything else. Personally I might raise my max charge to 90% and then just try not to let it get too low
The main reason to use a slower charger for overnight charging is that you likely have many of them lying around and don't need to purchase an expensive fast charger just so that your phone is fully charged an hour after you go to bed.
I had a similar experience with my 6S. I think as our phones age, websites and apps are optimized for newer, faster phones, and it really stresses an older phone to do normal everyday tasks that a newer phone wouldn't break a sweat with, so they spend a lot more time near 100% CPU utilization, draining the battery and generating heat (which also hurts the battery).
Please don’t follow or watch HTXStudio.
This person and their studio have used other people’s open-source code in their demos and falsely claimed to have written it themselves.
They are notorious in China for doing many foolish things and showing a lack of basic technical understanding.
Moreover, they appear to be backed by a mysterious group—no one knows how they managed to gain so many followers in a such short time.
This person and their studio have used other people’s open-source code in their demos and falsely claimed to have written it themselves.
They are notorious in China for doing many foolish things and showing a lack of basic technical understanding.
Moreover, they appear to be backed by a mysterious group—no one knows how they managed to gain so many followers in a such short time.
I didn’t say it doesn’t work. I just said it didn’t work for me.
Meanwhile, with my 13, I have a smart plug set up so it stops charging at 65% (don't need more that that, and I don't really have to "overthink" it, just plug and wait), same age as yours.. with a lower watt charger and through a cable, is at 94% so... well, it works for me.
Also I wonder if replacing a battery in a store is time consuming? Like how long do you have to be without your phone?
Last edited:
You said "Never once worked for me."
You have to give it time to learn your routine. It works in the background, like all algorithm's on Mac. It's not on demand.
My phone is on MagSafe (on a stand) most of the day. I'm not.... not using the capacity. I mean, I don't think I've seen my phone drop below 40% battery ever (with the charge limit turned on), so why not keep it at 80%?
Why is this triggering so many people? (especially on Reddit)
I slow charge my phones unless I need to fast charge. Why bother fast charging if it's not needed? And yeah, I have dozens of slow chargers that I've collected over the years. I use a Kindle charger - 9 Watts.
Nope. I gave it all the time in the world (a year or so) - it's meant for people who just plug in their laptop into power same time each night, not for me. You can easily mess it up by changing your routine for just a few days. Al Dente is so much easier. Also has some nice geeky info about power draw. Great for my needs - most of my days my Mac is plugged in, so I keep it below 70%, and I top it up with one click when I need to.
Also, on my other devices, it also just refuses to work. I always ended the day with more than 50% battery on my Watch so for a while it charged only to 80%.... until it just mysteriously stopped doing that and now it always charges to 100, even though my usage or battery levels haven't changed. Why? Apple only knows. For me, their 'estimates' are simply not reliable.
I’m aware of how it’s designed.
Never once worked for me in the sense that I gave it a try a few times over the years leaving it plugged in for days at a time and it still hasn’t worked.
I’m not sure I can elaborate on this further but I’m glad it’s working for you. And I’m happy with my solution that gives me more granular control.
Thanks for saving me the 7 minutes.
The creator of the video must be celebrating you guys destroying his views Lol
That's what people don't get. Most people charge over night then use their devices on battery. My MacBook Pro is almost always plugged in, so is my iPad Pro, and my iPhone is resting on MagSafe when not in use. If I didn't limit charging, they would be at 100% most of the day, every day.
And limiting them is not a hassle for me. Almost every device has this option, built it. My Steam Deck. My Switch 2. My Apple devices. And yet, people treat it like it's some kind of hoax.