Juli Clover from MacRumors talks about her one-year long experiment keeping the iPhone 15 Pro Max at an 80% charging limit:

My ‌iPhone 15‌ Pro Max battery level is currently at 94 percent with 299 cycles. For a lot of 2024, my battery level stayed above 97 percent, but it started dropping more rapidly over the last couple of months.

I left my ‌iPhone‌ at that 80 percent limit and at no point turned the setting off or tweaked it. There were some days when I ran out of battery because I was without a charger for most of the day, and there were other times that I had to bring a battery along to make sure I didn't run out of power. It wasn't always convenient to keep it at 80 percent, but there were days when it didn't have too much of an impact.

She used a 70/30 split between wired charging and MagSafe, and I used a 10/90 split between wired charging and MagSafe.

I went all MagSafe once the iPhones 12 were released.

Let’s compare her results to her other colleagues who did not use any charging limit:

1. Juli - Current capacity: 94%. Cycles: 299

2. Person 2 - Current capacity: 87%. Cycles: 329

3. Person 3 - Current capacity: 90%. Cycles: 271

There isn’t a huge difference in battery health, but here’s another crucial point that she brings up…

It's possible that the real gains from an 80 percent limit will come in two or three years rather than a single year, and I'll keep it limited to 80 percent to see the longer term impact.

I think this is where limiting the charging limit will really shine. Most people aren’t serial upgraders like ourselves who get the new phone every year or max every 2 years, but they will use their phone for 4 or 5 years.

These normal people will be able to maximize the performance of their iPhones, and they are the type of people who aren’t power users and won’t mind an 80% charge limit.

More power to them, literally.

As for my battery health? My first use date is October 9, 2023, and so far I have 285 cycles with a drumroll…

99% battery health as of today.

I’m not sure why mine is still at 99% especially when I predominantly use MagSafe charging, but I think Apple’s wireless charging protocols are very sophisticated. I’m sure that if I had just used a regular Qi charger, I would have closer to 90% in battery health due to the extra heat.

One thing to note. Many sites advertise their battery health when reselling iPhones, and many buyers ask about battery health as well. It is something that more people are becoming aware of (as they should because who wants to buy a dud iPhone that shuts off after a few hours?)

Great write-up and explanation of how the battery gets replaced in the new iPhone 16 lineup. Love the microscope images.

I recently replaced the battery in my original iPhone SE, and it was a pain to get those pull tabs out. I had to significantly bend the battery just to dislodge it at one point since the pull tabs were so fragile, and I had to tell my curious kids to back away since I didn’t know if the battery would explode.

The new method on the iPhone 16 lineup would have saved me at least an hour, plus the anxiety of potentially damaging my phone. Be careful though because if you reverse the polarity, then all the residue stays on the phone instead of the battery:

The reverse polarity did have an effect: when we reverse-zapped a new phone, the zap released the battery, but the adhesive residue stuck to the frame instead of the battery. Before that, a positive zap consistently left the residue on the battery. If you’re trying this at home, be sure to get the polarity right so you have less residue to clean up on the frame!