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

Apple Creator Studio iWork suite

Apple Pulls Keynote, Pages and Numbers From App Store [Update: Back]

Thursday October 22, 2026 11:01 am PDT by
Apple has temporarily removed Keynote, Pages, and Numbers from the App Store, just after releasing an update that added iPhone Duo support and a new Intelligent Assistant. It is not clear if the apps were removed intentionally, or if it is a bug. Apple has not said when the apps will be reinstated, but if it was in error, they should return soon. Update: The Mac versions are back without...
iphone duo screen crack in store

Crackgate? iPhone Duo Owners Report Screens Breaking Along the Hinge

Friday October 23, 2026 11:05 am PDT by
Some iPhone Duos are already experiencing hinge issues that cause display cracks, based on photos shared on Reddit and the MacRumors forums. Almost all of the display faults are right along the hinge, and most result in a line of bright pixels across one side of the screen. An iPhone Duo owner in Australia said his device cracked after being opened fewer than 20 times, and there was no...
Apple Music iPod Page Not Found

Apple Music Has a Hidden iPod You Can Play With

Friday October 23, 2026 7:11 am PDT by
Apple Music has a 404 page easter egg on the web: a functional iPod that appears when you load a page that does not exist, such as music.apple.com/macrumors. "Page Not Found," says Apple. "Give this a spin instead." Apple is clever with this. If you navigate to music.apple.com/ipod instead, the page says "Looking for something?" instead of "Page Not Found." The easter egg is only...

Top Rated Comments

cateye Avatar
13 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
13 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)
13 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)
13 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)
13 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)
13 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)
Latest Stories
'Arguably Better Than Face ID': the iPhone Duo Touch ID Tip to Try
'Arguably Better Than Face ID': the iPhone Duo Touch ID Tip to Try
1 hour ago
Verizon Apologizes for iPhone Duo Pre-Order Delays, Giving Customers $100 Gift Card
Verizon Apologizes for iPhone Duo Pre-Order Delays, Giving Customers $100 Gift Card
7 hours ago
Skip the Touch ID Scan: Unlock iPhone Duo With Apple Watch
Skip the Touch ID Scan: Unlock iPhone Duo With Apple Watch
7 hours ago
iPhone Duo Fails JerryRigEverything's Dusty Durability Test
iPhone Duo Fails JerryRigEverything's Dusty Durability Test
7 hours ago
Make iPhone Duo Volume Buttons Follow Screen Rotation
Make iPhone Duo Volume Buttons Follow Screen Rotation
9 hours ago
iPhone Duo Teardowns Reveal Two Batteries and More
iPhone Duo Teardowns Reveal Two Batteries and More
10 hours ago
M5 MacBook Air Returns to Prime Day Low With $200 Amazon Discount
M5 MacBook Air Returns to Prime Day Low With $200 Amazon Discount
11 hours ago
Top Stories: Apple 'Pro and Tell' Debut, iPhone Duo Launch, and More
Top Stories: Apple 'Pro and Tell' Debut, iPhone Duo Launch, and More
12 hours ago
Apple Store Pickup System for iPhone Duo Just Went Live Again in U.S. and Canada
Apple Store Pickup System for iPhone Duo Just Went Live Again in U.S. and Canada
13 hours ago
Apple Closes French Stores Ahead of Further Protests
Apple Closes French Stores Ahead of Further Protests
20 hours ago
Apple Pushes Back on DOJ Request for More Evidence
Apple Pushes Back on DOJ Request for More Evidence
21 hours ago
The iPhone Duo Can Be a Tiny Mac, a Toaster, and a Nintendo DS
The iPhone Duo Can Be a Tiny Mac, a Toaster, and a Nintendo DS
1 day ago
Using an Apple Pencil With the iPhone Duo: What to Know
Using an Apple Pencil With the iPhone Duo: What to Know
1 day ago
Apple Store Pickup for iPhone Duo Starting to Resume But Very Limited
Apple Store Pickup for iPhone Duo Starting to Resume But Very Limited
1 day ago
iPhone Duo Jailbroken on Launch Day
iPhone Duo Jailbroken on Launch Day
1 day ago
Apple Seeds Updated watchOS 27.2 Release Candidate
Apple Seeds Updated watchOS 27.2 Release Candidate
1 day ago
Apple Store in UK Reopens With New Design on iPhone Duo Launch Day
Apple Store in UK Reopens With New Design on iPhone Duo Launch Day
1 day ago
Crackgate? iPhone Duo Owners Report Screens Breaking Along the Hinge
Crackgate? iPhone Duo Owners Report Screens Breaking Along the Hinge
1 day ago
iPhone Duo Brings Back Long Lines at Apple Stores
iPhone Duo Brings Back Long Lines at Apple Stores
1 day ago
The MacRumors Show: iPhone Duo Arrives, Touchscreen MacBooks Next
The MacRumors Show: iPhone Duo Arrives, Touchscreen MacBooks Next
1 day ago
Apple Released iOS 27.1 for iPhone Duo Only
Apple Released iOS 27.1 for iPhone Duo Only
1 day ago
iPhone Duo: Open Two Apps Side by Side and Lock Them As an App Pair
iPhone Duo: Open Two Apps Side by Side and Lock Them As an App Pair
1 day ago
iPhone Duo Launches With Carrier and Accessory Discounts Available
iPhone Duo Launches With Carrier and Accessory Discounts Available
1 day ago
Apple Music Has a Hidden iPod You Can Play With
Apple Music Has a Hidden iPod You Can Play With
1 day ago
iPhone Duo Says 'Hello' to You Personally
iPhone Duo Says 'Hello' to You Personally
2 days ago
iPhone Duo: How to Skip the Swipe Up After Touch ID
iPhone Duo: How to Skip the Swipe Up After Touch ID
2 days ago
Where to Buy iPhone Duo Today: Stores, Pickup, and Wait Times
Where to Buy iPhone Duo Today: Stores, Pickup, and Wait Times
2 days ago
MacBook Neo Helps Apple Outpace Rivals as Market Declines
MacBook Neo Helps Apple Outpace Rivals as Market Declines
2 days ago
Happy 25th Anniversary, iPod
Happy 25th Anniversary, iPod
2 days ago
iPhone Duo Demand Reportedly Exceeds Apple's Expectations
iPhone Duo Demand Reportedly Exceeds Apple's Expectations
2 days ago