ASUS ROG Phone 3 battery tested: Is it the new battery life champion?

The ASUS ROG Phone 3 houses a gargantuan 6,000mAh battery which is one of the largest on the market to date, and with good reason. The handset packs in a powerhouse Snapdragon 865 Plus processor, a zippy 144Hz AMOLED display, and is tasked with keeping gamers juiced up for those long play sessions.

The ROG Phone 3 is purpose-built to offer high performance and still last a full day of heavy use. However, keen-eyed observers will have spotted the ROG Phone 3 offers the same battery capacity as its predecessor, the ROG Phone 2. So just how far can you push the more powerful ROG Phone 3’s battery life? That’s what we’re here to find out.

Our verdict: ASUS ROG Phone 3 review: A gaming powerhouse for everyone

Before we get into the numbers, here’s a quick rundown of how the ROG Phone 3’s competitors stack up for battery capacity. Note that there are phones out there like the Oukitel K13 Pro, which offers a colossal 11,000mAh battery. But we don’t consider it a competitor because these super-sized battery phones typically target a very low performance point. The Pixel 3a XL is also a really long-lasting phone but again, it doesn’t meet our gaming phone criteria.

While smartphone battery capacity continues a generally upward trajectory, 6,000mAh batteries remain rare. The phone’s closest 2020 competitors tend to land on and around the 5,000mAh mark.

On paper, this gives the ROG Phone 3 a healthy advantage and we would expect the phone to offer competitive — if not better — battery life than its rivals. Of course, there’s much more to long battery life than just cell capacity, so let’s dive into some benchmarks.

Benchmarking a battery

To obtain consistent battery-life results across devices, we turn to our in-house Speed Test G benchmark, which loops through a series of benchmark tests to stress the CPU, GPU, and memory until the battery gives out. We treat it as a pretty much worst-case scenario for screen-on time, as few people — if any — will run games on their phone for a full battery cycle.

The result provides us with a very good estimate of how long a phone lasts given a continuous heavy workload.

The ASUS ROG Phone 3 doesn’t quite top our benchmark charts, but it puts in an excellent performance. At five hours and 48 minutes, ASUS’ latest gaming smartphone can handle exceedingly long gaming sessions with battery life to spare.

Impressively, the ROG Phone 3 outlasts its predecessor despite packing in more powerful hardware. Even with gaming sessions thrown in, you’d really be hard-pressed to run this phone down in a single day. For more typical day-to-day usage, this handset offers some seriously incredible battery life and peak performance.

Overall, the phone clocks in third place out of comparable devices. It’s behind the HUAWEI P40 Pro Plus and Xiaomi Mi 10 Pro, but is right in the mix with the LG V60 and POCO F2 Pro.

HUAWEI and Xiaomi’s phones have smaller batteries, but are known for heavy-handed optimizations that throttle back performance in exchange for longer battery life. HUAWEI’s Kirin 990 (found in the aforementioned P40 Pro Plus) doesn’t reach the lofty performance heights of the ROG Phone 3’s Snapdragon 865 Plus either. With that in mind, we should have a quick look at the performance results from this benchmark to see if that also plays a part in the story.

Here’s where things become very interesting. The ASUS ROG Phone 3 offers up faster and more consistent performance than all of the phones that scored higher or similar in our battery benchmark. Under stress, the phone has equivalent battery life to the LG V60, HUAWEI P40 Pro Plus, and POCO F2 Pro, but provides faster and more sustainable performance.

The ROG Phone 3 only marginally loses out to the OnePlus 8 Pro, realme X50 Pro 5G, and Samsung Galaxy S20 Ultra in terms of sustained performance, but the latter manages five hours of life under our stress test compared to the ROG’s five hours and 48 minutes. Meanwhile, the realme X50 Pro survived just over four hours while the OnePlus 8 Pro clocks in just three hours and 30 minutes. The takeaway is that ASUS doesn’t have to sacrifice performance or battery life, enjoying the best of both. All thanks to its 6,000mAh cell.

Finally, it’s worth noting that switching on X Mode — a high performance mode that can dynamically overclock the CPU to an intimidating 3.1GHz — sees the ASUS ROG Phone 3 surpass its rivals in terms of performance and consistency. However, this mode drains the phone’s battery substantially faster, resulting in just over three hours and 20 minutes of heavy use time. The Qualcomm Snapdragon 865 Plus looks like a power-hungry beast when running flat out.

ASUS ROG Phone 3 battery: The verdict

The ASUS ROG Phone 3’s 6,000mAh battery doesn’t disappoint. Although the phone doesn’t run away with our battery benchmark crown — as some may have expected — it hands in a very impressive almost six-hour result. Remember that the phone is powering a 144Hz display and a more powerful Snapdragon 865 Plus processor than the current competition too. Our benchmark is also an example of the harsher use cases for screen-on time.

The ROG Phone 3 will last notably longer when browsing the web, checking email, and all that other less demanding humdrum stuff we use our phones for. If you do somehow manage to run down the 6,000mAh battery, the handset’s 30W quick charging solution fully powers the battery back up in 107 minutes or about 87% in just one hour.

One final point on the handset’s battery, we did notice some variation in screen-on time during our review. ROG Phone 3 lasts as long as nine hours and 21 minutes with 5% battery left during more typical day-to-day use, but other days only managed seven hours. We believe this wide margin is due to the variable 144Hz refresh rate and just how many demanding applications you can run in a day.

The inconsistent battery life is becoming quite a bit more common as the industry embraces more power-hungry variable refresh rate displays. The bottom line is that anywhere from six to over nine hours of screen-on time is simply fantastic for such a high-performance smartphone.

Read next: The Best of Android: Mid-2020 — Which phone has the best battery life?