iPhone 18 Pro: How to Really Get 50% in 15 Minutes
In my first test I missed Apple’s promise. Instead of 50%, my iPhone 18 Pro Max only reached 47% after 15 minutes. That video sparked one of the best comment discussions I’ve ever had, with lots of you trying to work out why. I checked the theories and ran the test again. This time it worked: 51% in 15 minutes. But only under very specific conditions.
The Theories from the Comments
The 60 watts. Apple’s charger is rated for up to 60W peak. One viewer did the math and concluded that the iPhone can’t actually reach that. That matches my measurements, since I never saw more than about 53W.
The cable. Some suspected the cable was too weak. It isn’t. The 3-amp USB-C cable from the iPhone box is enough.
The SIM slot. An interesting theory: European models have a SIM card slot that takes up battery space, while US models don’t have one. That could mean the battery is built differently here. I can’t rule it out, and I haven’t tested it.
My Guess: Two Factors
I had two other suspects. The first was my USB meter, which sat between the cable and the iPhone in the first test and draws a bit of power itself. The second was room temperature. According to Apple, the iPhone charges best at 16 to 22°C, and in my first test it was at least 22°C. The warmer the iPhone gets, the sooner it throttles charging to protect the battery.
The Second Test: Down to the Basement
So I took the iPhone down to the basement, where it’s about 18 to 19°C, and laid it directly on the tiles for extra cooling. I left the meter out. I charged with Apple’s 40W Dynamic Power Adapter and the original cable again, starting from a completely empty battery.
It got tense along the way. After 10 minutes I took a quick look, and the display showed only 46%. I thought it was going to be even worse than the first time. Then the iPhone picked up speed again in the last few minutes. After 15 minutes it showed 51%, beating Apple’s promise by 1%.
You could see the difference in temperature too. This time the back only reached about 36°C, compared with 38°C at the same spot in the first test.
Where the Mistake Was
The meter was probably responsible for about 1%, maybe even less. The main reason was temperature. The cool room and the tile kept the iPhone slightly chilled the whole time, so it could sustain high charging power for longer.
What This Means for Everyday Use
- The 40W Dynamic Power Adapter with 60W Max is uniquely designed to dynamically deliver up to 60W of output, providing a powerful boost in charging speeds.
- With Dynamic Power, you get many of the same benefits of higher-wattage chargers in a compact, pocket-size form factor to make charging at home, in the office, or on the go faster and more convenient than ever.
- For fast charging, pair the Dynamic Power Adapter with iPhone 17 models (50 percent battery in around 20 minutes) or iPhone Air (50 percent battery in around 30 minutes).
- Compatible with USB-C–enabled devices. Charging cable sold separately.
Apple’s 50% in 15 minutes is a best-case figure, and Apple says as much in the fine print. You can hit it when these things come together:
✓ Battery starts at 0%
✓ Apple’s 40W Dynamic Power Adapter, or a charger where the iPhone actually uses AVS
✓ A cool environment, ideally below 20°C
✓ The iPhone lies uncovered, not on a blanket or in direct sunlight
✓ No adapters or meters in between
If you charge overnight in a normal 22°C bedroom, at your desk during the day, or in summer, you probably won’t quite hit 50% in 15 minutes. That’s not a problem, though, because 47% is still fast.
To find out whether your own charger is fast enough for the iPhone 18 Pro, try my free Charge Check.
What’s Next?
I’ve picked up two more chargers. One costs about $16 and is supposed to do everything Apple’s charger does. The other is a new Ugreen charger with AVS and USB PD 3.2. With the first Ugreen, the iPhone wouldn’t accept AVS. I’ll show you in the next test whether it works this time.
More iPhone 18 Pro Tests
To keep your new iPhone in good shape, you’ll find my test winners among the iPhone 18 Pro cases and iPhone 18 Pro screen protectors. If you’re waiting for the foldable iPhone, check out my tests of iPhone Duo cases and iPhone Duo screen protectors.