What really happens to your iPhone's battery health when you charge to 80% instead of 100%
If you have ever wondered what happens to your iPhone’s battery health if you never charge it to 100% then look no further.
This is because one woman has conducted an experiment where she only charged her device to 80% for an entire year.
She shared her finding in a post on MacRumors, where she explained that the test was done in order to test the ‘limits on battery longevity’.
In the piece, she wrote: “Since September 2024, my iPhone 16 Pro Max has been limited to an 80 percent charge, with no cheating. As of today, my battery's maximum capacity is at 94 percent with 299 charge cycles.
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“With last year's test, I spent a lot of time with my battery below 20 percent. I saw some comments suggesting that draining it so low could also affect battery capacity over time, so this year, I tried hard to keep my battery between 20 and 80 percent. I wasn't always successful, but my iPhone 16 Pro Max was in that middle charge area most of the time.”
The woman went on to say that she believes her battery capacity is ‘about average’, having found that her previous experiment with her iPhone 15 Pro Max also left the device at 94% battery capacity after a year.
She continued: “I did a mix of charging via MagSafe and charging with USB-C, and my iPhone 16 Pro Max can get hot when charging over MagSafe, especially with MagSafe battery packs. Since I was trying to keep above a 20 percent charge, I did more wireless charging when I was out. I can't help but wonder if heat was an issue this year.
“It continued to be inconvenient limiting my iPhone battery to an 80 percent charge. It was fine when home, but if I was out and wanted to use the camera or needed GPS, it often wasn't enough battery. When you set an 80 percent charge limit, the iPhone will charge to full every so often to calibrate, and I appreciated surprise days with 20 percent extra battery.”
So, was it worth it? Apparently not, as the woman detailed the effort taken to keep her phone at a maximum of 80% charge, admitting that she had found the results to be ‘disappointing’.
She added: “I have upgraded to the iPhone 17 Pro Max and did already limit it to an 80 percent charge for another 12-month test. I'm interested to see how the larger battery changes things, and whether the switch to aluminum will make a difference.”