With the iPhone 15 series, I did an experiment and kept my iPhone's Charge Limit set at 80 percent for an entire year. It provided an interesting look at the impact of charge limits on battery longevity, so I decided to repeat it for the iPhone 16 line.
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.
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.
You can compare your own battery health with mine, but my guess is that my 94 percent battery capacity is about average, regardless of whether charging limits are on or off. In fact, my iPhone 15 Pro Max was also at 94 percent capacity at the 12 month mark when I did this same test last year.
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.
If I had to guess, I probably had a 50/50 split between MagSafe charging and fast charging with USB-C. Most charging was indoors at around 72 degrees, but there were times when I was outdoors with a battery pack in warmer conditions.
I use my older iPhones for software tests, so my iPhone 15 Pro Max is still around. At the two year mark, its capacity is 88 percent, down from 94 percent in September 2024. It has 352 cycles, and I've kept it at the 80 percent limit.
During this year's testing, my iPhone 16 Pro Max battery was still at around 98 percent just a couple of months ago, so I thought the limit was having more of an impact, but I saw a decent drop as we got closer to September. It was even at 95 percent about a week ago, but now I'm down to 94 percent.
I now have two years of data with my iPhone limited to an 80 percent charge, and I don't think it's been worth it. My coworker who also has a 16 Pro Max did not have an 80 percent charge limit set, and his battery capacity is 96 percent with 308 charge cycles.
Maybe setting an 80 percent limit improves battery health over a longer period of time, but over a one-year period, the results have been disappointing. Setting charging to a 90 or 95 percent might make more sense.
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.
What's your iPhone battery capacity and cycle count? Let me know in the comments below, and weigh in on whether you think the 80 percent charge limit is a good idea.
