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

m1 chip slide

Five Years of Apple Silicon: M1 to M5 Performance Comparison

Monday November 10, 2025 1:08 pm PST by
Today marks the fifth anniversary of the Apple silicon chip that replaced Intel chips in Apple's Mac lineup. The first Apple silicon chip, the M1, was unveiled on November 10, 2020. The M1 debuted in the MacBook Air, Mac mini, and 13-inch MacBook Pro. The M1 chip was impressive when it launched, featuring the "world's fastest CPU core" and industry-leading performance per watt, and it's only ...
iOS 26

iOS 26.2 Available Next Month With These 8 New Features

Tuesday November 11, 2025 9:48 am PST by
Apple released the first iOS 26.2 beta last week. The upcoming update includes a handful of new features and changes on the iPhone, including a new Liquid Glass slider for the Lock Screen's clock, offline lyrics in Apple Music, and more. In a recent press release, Apple confirmed that iOS 26.2 will be released to all users in December, but it did not provide a specific release date....
All Screen iPhone 2027 Feature 1

Apple to Hide Selfie Camera Under Display of 20th Anniversary iPhone

Monday November 10, 2025 1:55 am PST by
Apple will conceal the front-facing camera under the screen of its 2027 iPhone, a Chinese leaker said today, corroborating reports that Apple's 20th anniversary iPhone will have no visible cutouts in the display. Weibo-based account Digital Chat Station said Apple's development of under-screen camera technology was progressing as planned for adoption in 2027, one year after it will...
iphone pocket%402x

Apple Debuts iPhone Pocket, a Limited Edition iPod Sock-Style Accessory

Tuesday November 11, 2025 1:23 am PST by
Apple has teamed up with Japanese fashion house ISSEY MIYAKE to launch iPhone Pocket, a 3D-knitted limited edition accessory designed to carry an iPhone, AirPods, and other everyday items. The accessory is like a stretchy pocket, not unlike an iPod Sock, but elongated to form a strap made of a ribbed, elastic textile that fully encloses an iPhone yet allows you to glimpse the display...
iphone air thinness

iPhone Air Sales Are So Bad That Apple's Delaying the Next-Generation Version

Monday November 10, 2025 11:41 am PST by
The thin, light iPhone Air sold so poorly that Apple has decided to delay the launch of the next-generation iPhone Air that was scheduled to come out alongside the iPhone 18 Pro, reports The Information. Apple initially planned to release a new iPhone Air in fall 2026, but now that's not going to happen. Since the iPhone Air launched in September, there have been reports of poor sales...
Early Black Friday Deals 1

The Best Early Black Friday Apple Deals on AirPods, Apple Watch, iPad, and More

Saturday November 8, 2025 6:16 am PST by
We're officially in the month of Black Friday, which will take place on Friday, November 28 in 2025. As always, this will be the best time of the year to shop for great deals, including popular Apple products like AirPods, iPad, Apple Watch, and more. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When ...
homepod mini colors

New HomePod Mini Coming Soon With These Features

Tuesday November 11, 2025 7:30 am PST by
Apple is expected to announce a new HomePod mini imminently, headlining with new chips. Here are all of the new features we're expecting. The second-generation HomePod mini is highly likely to contain a more up-to-date chip for more advanced computational audio and improved responsiveness. The current HomePod mini is equipped with the Apple Watch Series 5's S5 chip from 2019. Apple is likely ...
Apple fitness plus feature

Future of Apple Fitness+ 'Under Review'

Sunday November 9, 2025 5:30 am PST by
The future of Apple Fitness+ is "under review" amid a reorganization of the service, according to Bloomberg's Mark Gurman. In the latest edition of his "Power On" newsletter, Gurman said that Apple Fitness+ remains one of the company's "weakest digital offerings." The service apparently suffers from high churn and little revenue. Nevertheless, Fitness+ has a small, loyal fanbase that...
iphone black friday gold

The Best Early Black Friday iPhone Deals

Monday November 10, 2025 10:18 am PST by
Cellular carriers have always offered big savings on the newest iPhone models during the holidays, and Black Friday 2025 sales have kicked off at AT&T, Verizon, T-Mobile, and more. Right now we're tracking notable offers on the iPhone 17, iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air. For even more savings, keep an eye on older models during the holiday shopping season. Note: MacRumors is...
2024 iPhone Boxes Feature

Apple Adjusts Trade-In Values for iPhones, iPads, Macs, and More

Thursday November 6, 2025 11:12 am PST by
Apple today updated its trade-in values for select iPhone, iPad, Mac, and Apple Watch models. Trade-ins can be completed on Apple's website, or at an Apple Store. The charts below provide an overview of Apple's current and previous trade-in values in the U.S., according to its website. Maximum values for most devices either decreased or saw no change, but the iPad Air received a slight bump. ...

Top Rated Comments

cateye Avatar
5 days ago at 01:23 pm
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: 122 Votes (Like | Disagree)
dustin_ Avatar
5 days ago at 01:24 pm
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)
el-John-o Avatar
5 days ago at 01:38 pm
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)
ValerieDurden Avatar
5 days ago at 01:38 pm

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)
LowKeyed Avatar
5 days ago at 01:31 pm
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)
0423MAC Avatar
5 days ago at 01:31 pm
It just doesn’t make sense to limit yourself to stay within a range now to possibly save a few percentage points later.
Score: 28 Votes (Like | Disagree)