For the first six months of owning an iPhone 15 Pro Max, my battery health never dipped below 100 percent. That might not seem like a big deal, but when you consider my iPhone 14 Pro Max lost about a percentage point each month the previous year, I was extremely impressed by the battery’s ability to retain its full capacity so long after I bought it.
In the past three weeks, it hasn’t been so great. In early April I noticed that my battery health had finally dropped to 99 percent, as expected after six months of use and daily charging. But throughout April and May it’s dropped about one percent each week and now stands at 92 percent. Even if the pace slows some, there are five months until the iPhone 16 arrives, so it’s likely that my battery health will dip to around 85 percent or less.
That might not seem catastrophic, but it’s a steep drop from just a couple of generations ago when battery health would stay in the mid-90s after a year. And that’s when the iPhone battery was only guaranteed for 500 cycles. Now, Apple says batteries of iPhone 15 models are designed to retain 80 percent of their original capacity at 1,000 complete charge cycles under “ideal conditions.” I’m only at 270 cycles, but the recent rate of decline has me concerned about just how long my iPhone 15 Pro Max will last.
Foundry
I don’t think I’m doing anything different than most people do. I generally charge it overnight attached to a magnetic charger on my nightstand and keep 80% Limit on most days. I don’t let my phone get to zero very often, usually charge it when it hits the red, and rarely charge it just because I’m sitting at my desk. But still, my battery health is dropping quite a bit.
As a Macworld reader points out, my reliance on wireless charging could be the culprit. He shared an iFixit article that looks at the efficiency of wireless charging vs wired charging and concludes that a lot of energy is wasted when placing your phone on a wireless charger:
Over two hours and 10 minutes, the phone charged from 0% to 100% and had a peak power draw of 20W at the 30% charge mark. The battery temperature also peaks shortly after at 30°C and begins to decline back down as the battery cell fills and the power draw from the mains also declines. The total energy used to fully charge a 12.7Wh battery was 18.25Wh, which means there was a 5.55Wh or 35.9% loss of energy. That’s a lot of waste, and it’s also our best case scenario.
That wasted energy could easily be causing my battery to degrade quicker than it should and be responsible for the recent degradation. However, I’m willing to bet that more than 90 percent of iPhone users rely on either MagSafe or wireless charging to fill up their iPhones—and probably won’t stop after reading this.
Granted, most people don’t check their battery health weekly and many don’t even know it exists. However, they will notice when their phone starts dying sooner in the day. We expect iPhones to last many years, and with the latest chips and displays, along with 4-5 years of iOS updates, they generally do. But with my iPhone 15 Pro Max, I wonder if the battery will keep up.
For advice on charging your iPhone read: How to charge an iPhone properly.
Author: Michael Simon, Executive Editor, Macworld
Michael Simon has been covering Apple for more than 20 years. He started covering rumors with Spymac when the iPod was the iWalk, and has owned nearly every iPhone Apple has ever made. He lives in Connecticut with his wife, son, and far too many gadgets.