What a great season it has been in the flagship phone race. It starts in early fall with releases like the iPhone 15 Pro Max and Pixel 8 Pro and then continues in the new year with the Galaxy S24 Ultra and OnePlus 12. Now that all the major phone manufacturers have released their flagship models, we can properly test them to find out which model can top our list of the best cell phone battery lives.
To earn a spot, these flagships must exceed the 10-hour average battery life that most phones achieve in our custom battery benchmark test. How do we test smartphone battery life? This involves using a light meter to calibrate the displays to 150 nits and then running a script that simulates web browsing over a 5G cellular connection. This continues until the batteries are empty.
The improvement in battery life tended to be gradual, typically beating previous models by an hour. However, this graduating class took bigger steps to go beyond the one-hour improvement in battery life. In this Galaxy S24 Ultra vs. iPhone 15 Pro Max vs. OnePlus 12 vs. Pixel 8 Pro battery life showdown, we’ll go over how long they last to ultimately crown a winner – and how quickly they charge.
Flagship phone battery life tested
| phone | Battery size | Battery test result (hrs mins) |
| OnePlus 12 | 5,400mAh | 5:41 p.m |
| Galaxy S24 Ultra | 5,000mAh | 4:45 p.m |
| iPhone 15 Pro Max | 4,422mAh | 2:02 p.m |
| Pixel 8 Pro | 5,050mAh | 10:03 |
Starting with the shortest battery life, the Pixel 8 Pro comes in last with a time of 10 hours and 3 minutes. Technically, it has the third largest battery capacity, but it appears that the Tensor G3 is the least power efficient of them all. Although it offers the shortest battery life of this flagship group, it’s an improvement over its predecessor’s subpar 7 hours and 55 minutes. From that perspective, it’s still a significant improvement for Google.
Third place goes to the iPhone 15 Pro Max, which achieved 14 hours and 2 minutes in our benchmark test. Apple’s latest silicon, the A17 Pro, makes significant progress in processing, which also contributes to the phone’s improved battery life. The previous iPhone 14 Pro Max achieved a time of 13 hours and 39 minutes before failing.
Our runner-up in this battery life showdown goes to the Galaxy S24 Ultra and its beefy 5,000mAh battery. What’s impressive here is that the battery capacity isn’t as large as the Pixel 8 Pro, meaning its endurance is the result of the excellent power efficiency of its chipset – the Snapdragon 8 Gen 3 – resulting in a time of 16 hours and 45 hours Protocol. Samsung’s latest flagship easily beats the iPhone 15 Pro Max by almost three full hours and its predecessor by over 3.5 hours.
Qualcomm deserves due recognition as its Snapdragon 8 Gen 3 catapults our top pick to new heights. The OnePlus 12 is the unanimous winner in this battery endurance test with its incredible time of 17 hours and 41 minutes.
Of course, we can thank the 5,400mAh battery for its extra long runtime, but it has a lot more to offer as the Snapdragon 8 Gen 3 is much more energy efficient compared to the other chipsets. What’s even more notable is that the OnePlus 12 beats its predecessor, the OnePlus 11, by around 4.5 hours, which says a lot about the jump in battery life we’re seeing this time around.
If things stay on track, we could very well see the next batch of top phones get closer to the 20-hour mark on our battery benchmark test. While there haven’t been any major changes in the battery technology of today’s phones, many of the improvements we’re seeing here come from the optimizations of these chips.
Tested charging the flagship phone battery
| phone | Recharge percentage (15 min) | Recharge percentage (30 min.) |
| OnePlus 12 | 60% | 100% |
| Galaxy S24 Ultra | 39% | 71% |
| iPhone 15 Pro Max | 20% | 41% |
| Pixel 8 Pro | 29% | 59% |
It certainly helps to have more gas in the tank, but also a phone that charges quickly. Fortunately, many flagships use their own fast charging technology to bring their battery capacities to a decent level with a short charge.
Even though many were happy about Apple’s introduction of USB-C, the iPhone 15 Pro Max still takes a long time to charge. In fact, it manages to reach 41% after 30 minutes of charging. This is due to the slower 20W wired charging speed, which is a record in the world of flagships.
Next on the charging list is the Google Pixel 8 Pro, which achieves a better capacity of 59% in 30 minutes of charging. That’s not too bad considering it benefits from a slightly faster 30W wired charging speed.
The Galaxy S24 Ultra still takes second place in our battery charging test, achieving a commendable 71% in 30 minutes. This is possible thanks to the faster wired charging speed of 45W, even though the device remains unchanged from its predecessor. If you’re short on time, we also think the 39% charge level with 15 minutes of charge time is respectable if you need to top up.
Finally, there’s the OnePlus 12 with its obscene 80W wired charging that charges the phone to 100% in 30 minutes. It outperforms all other flagships here, but the charge level of 60% with 15 minutes of charging time is equally impressive. OnePlus puts a lot of emphasis on the battery and charging, as other newer versions like the OnePlus Open and the 12R also achieve impressive results.
OnePlus also deserves credit for being one of the few phone makers to include a charging adapter with its phones. The OnePlus 12, for example, comes with an 80W charging adapter – while the other phones require a separate purchase.
