In-Depth iPhone Battery Experiment Pits Slow Charging Against Fast Charging - MacRumorsOpen MenuShow RoundupsShow Forums menuVisit ForumsOpen Sidebar
Skip to Content

In-Depth iPhone Battery Experiment Pits Slow Charging Against Fast Charging

HTX Studio this week shared the results from a six-month battery test that compared how fast charging and slow charging can affect battery life over time.


Using six iPhone 12 models, the channel set up a system to drain the batteries from five percent and charge them to 100 percent over and over again. Three were fast charged, and three were slow charged.

Another set of iPhones underwent the same test, but with charging initiated at 30 percent and stopped at 80 percent, so the iPhones were always in that range.

Prior to the experiment, the capacity for each phone was tested, and after 500 cycles, the capacity was tested again. The results suggest there is minimal additional battery drain from fast charging, but keeping an iPhone between 30 and 80 percent charge could be minimally beneficial.

HTX Studio concluded that the best way to charge an iPhone is "however you like," without overthinking it and trading mental energy for a tiny bit of battery life. The same video also includes Android tests, and is well worth watching in full for those curious about the effects of fast charging.

Popular Stories

iOS 27 Next to iPhone

Here's When iOS 27 Rolls Out Today in Every Time Zone [Update: It's Out]

Sunday September 13, 2026 3:00 am PDT by
Update 10:04 a.m.: iOS 27 is rolling out now, though it may take a bit for all users to see it, so keep checking! Apple is about to release iOS 27, which will finally deliver more advanced Siri AI capabilities as well as a variety of other refinements, improvements, and new features to iPhones. It's Apple's biggest software update of the year, and Apple announced at Wednesday's iPhone event...
iOS 27 Icon iPhone

iOS 27 Available Now With These 8 New Features

Monday September 14, 2026 9:00 am PDT by
Update — 10 a.m. Pacific Time: Apple has released iOS 27. During its iPhone 18 Pro and iPhone Duo event last week, Apple announced that iOS 27 will be released widely on Monday, September 14. iOS 27 should be available around 10 a.m. Pacific Time / 1 p.m. Eastern Time today via the Settings app, under General → Software Update. Below, we have highlighted eight new features and...
Apple iCloud Plus expansion hero

iCloud+ Now Includes Apple TV, Apple Arcade, and Curated Apple Music Stations in Over 100 Countries

Tuesday September 15, 2026 1:43 am PDT by
Apple today announced a new subscription initiative that turns paid iCloud+ subscriptions into a broader services bundle in more than 100 countries. In select countries, Apple says every paid iCloud+ plan, including the cheapest 50GB tier, now includes Apple TV and Apple Arcade "at no additional cost," while family sharing extends the storage, TV and Arcade access to up to five people....

Top Rated Comments

cateye Avatar
11 months ago
Telling people to not “overthink” battery life and charging, and backing it up with data, is going to absolutely rock the world of a great number of posters in the iPhone forum. Thoughts and prayers.
Score: 123 Votes (Like | Disagree)
dustin_ Avatar
11 months ago
wow, just like every other battery test. replace your battery if/when it falls under 80%. otherwise, use your phone as you see fit, folks.
Score: 43 Votes (Like | Disagree)
11 months ago
This comes up a lot and every test is more or less the same.

Marginal benefits if you make some pretty significant compromises every day for forever.

If you only charge to 80%, your capacity will hold slightly longer. Capacity that... you're not using.

If you fast charge every day for years all the way to 100%; you'll still have 80% capacity at the end of several years. Capacity that you would've been artificially limiting yourself to the entire time.

Feels very "cover the couch in plastic" to me. Sure I guess it improves it somewhat; but is it worth not getting to actually use the "thing"?

And ultimately, battery replacements from Apple are both reasonably priced and available for a very long time, with third party options virtually indefinitely.

I keep my phones for a really long time so, in theory, I'm the one this information most benefits. The only thing I actually do is make sure to use a slow charger on my nightstand. When I plug it in at night, it's going to be plugged in for the next several hours so there's no benefit to fast charging. Beyond that, it gets hit with a fast charger if I ever need to charge in the middle of the day. Always to 100%. And after 3-4 years the battery capacity starts to get noticeably poorer. A hundred bucks (give or take) at the Apple Store (free with AppleCare+) and I walk away with a brand new battery. And most people will have replaced their phone long before then.
Score: 42 Votes (Like | Disagree)
11 months ago

It just doesn’t make sense to limit yourself to stay within a range now to possibly save a few percentages later.
The 80% crowd isn’t going to like that lol.
Score: 35 Votes (Like | Disagree)
11 months ago
I've always been a fan of the idea that your phone (or any device) should work for you, not the other way around. If it is easy for you to manage your battery, great. But don't work so hard for it. You are unlikely to significantly change the usable life of a modern battery and compared to the effort some people put into it, it is not a smart trade.

I've always felt the same way about OSes. You shouldn't have to work so hard to keep your OS organized, secure, updated, etc., again, you got a computer/device to improve your life, not complicate it.
Score: 34 Votes (Like | Disagree)
11 months ago

It just doesn’t make sense to limit yourself to stay within a range now to possibly save a few percentage points later.
For sure.

If you limit yourself to 80% then after 4 or 5 years you can avoid a battery that only... has 80% of it's capacity left?

What exactly have you accomplished?

Let's imagine a phone owned for 6 years. One person limits it to 80% and has 80% capacity for 6 years. The other person doesn't limit it at all and ends up with 80% capacity and maybe a smidge under for a year or two?

...I really don't get it. Like genuinely. How is the first scenario not the obviously, clearly, no brainer, no question worse scenario? How is a capacity life of 100, 96, 92, 88, 82, 80 better than a capacity lifetime by year of 80, 80, 80, 80, 80, 80?
Score: 28 Votes (Like | Disagree)