I tested the OnePlus 15, and its battery life blew me away

Single-day battery life has been the norm for far too long. The OnePlus 15 proves we can do better.

Almost every aspect of Android phones today is superior to phones from just a few years ago. Such is the nature of a highly competitive industry like smartphones. Thanks to technological advancements, smartphones today have better displays, faster processors, more intelligent software, and even larger batteries than before. Yet, despite these continued improvements, one aspect has remained frustratingly stagnant: battery life. Most smartphones still last only a single day on a full charge — if even that.

In recent years, we’ve seen battery technology improve and capacities increase, but these advancements were always offset by manufacturers coupling them with bigger, brighter, faster-refreshing displays and increasingly power-hungry system-on-chips. The rise of computationally intensive generative AI features has only exacerbated the issue. Many people accept this trade-off so long as their phones simply survive a heavy day of use, as if it’s a given that we simply have to charge our smartphones every night.

But something significant has happened in the latter half of 2025. A new crop of Android phones, utilizing ultra high-density silicon-carbon batteries, is challenging this norm. We’re seeing a new wave of smartphones with batteries that exceed 7,000mAh, and the new OnePlus 15 is one of the few bringing this breakthrough to North America.

I’ve been using the OnePlus 15 for the past two weeks, and I believe it’s a sign that we’re entering a new era in smartphone battery life: the two-day phone.

OnePlus 15 and the rise of the two-day smartphone

Before the OnePlus 15, I settled on expecting my smartphones to only last me one full day. While I didn’t exactly have day-to-day battery anxiety with my previous phones, the Xiaomi 15 Ultra, the Samsung Galaxy Z Fold 7, and the Samsung Galaxy S25 Ultra, I knew that if I ever needed to push any of these devices to their limits throughout the day, I would likely be reaching for a charger before the day’s end. Only the OnePlus 15’s predecessor, the OnePlus 13, was reliable enough to get me through a heavy day of use no matter what, but even that device couldn’t carry me through a second day without a quick top-up.

In terms of raw numbers, the 7,300 mAh battery in the OnePlus 15 might not seem like a dramatic leap over the 6,000 mAh battery in the OnePlus 13. However, you have to consider that the OnePlus 13 already boasts one of the largest batteries in the North American flagship market — besting the Google Pixel 10 Pro XL with its 5,200mAh battery, the Samsung Galaxy S25 Ultra with its 5,000mAh battery, and the iPhone 17 Pro Max with its 5,088mAh battery. In that context, the OnePlus 15’s battery becomes all the more impressive.

It pushes the device past the threshold of “great single-day battery” into “multi-day battery.” Other recent flagships I’ve used comfortably lasted me a full day but couldn’t reliably get me through an entire second day. Even the OnePlus 13 could only last me well into a second day, but the OnePlus 15 gives enough breathing room to last through it.

You can push the OnePlus 15 to its limits on day one and still have enough juice for a light day two. Alternatively, you can put it through moderate use for two full days before needing to find an outlet. During my time with the device, I found myself only charging it every other day. I no longer worry about charging my phone every night just to ensure I can use it the following day.

A weekend without battery anxiety

This enhanced capacity generally makes you think less about when you need to top up. I really noticed this during a recent weekend trip to Austin, Texas.

On the drive there, I plugged my phone into my car in order to use wired Android Auto, but the moment I arrived, I unplugged it. And for the next 48 hours, I didn’t charge my phone at all.

During that time, I used my phone to browse the web, scroll through Reddit, watch shorts on YouTube, listen to music, respond to emails, and check messages on Discord, Telegram, Slack, and X. All typical things I do during the day. By the time we departed Austin, I had logged approximately 12 hours of screen-on time, and my phone still had about 15% battery life remaining.

Due to the fact that OxygenOS 16 does not track battery usage since the last full charge, but rather per full day, I wasn’t able to get statistics for the first 6 hours of battery use (the evening I arrived in Austin).

In contrast, my brother, who has an iPhone 14 Pro Max, was repeatedly topping up his device during our stay. He charged his phone overnight, and whenever we returned to our friend’s apartment, he constantly had to manage his phone’s battery level to ensure he had enough power for the next outing. Meanwhile, I was comfortable just leaving my phone out. Its battery was reliable enough for me not to even consider charging it.

This experience reminded me of when I first got the OnePlus Watch 2. That device completely changed how I view smartwatch battery life. Ever since I got it, I no longer bother bringing a watch charger with me on short trips, doubly so since I upgraded to its successor, the OnePlus Watch 3. While the OnePlus 15 doesn’t offer that same level of multi-day freedom, the fact that I don’t have to scramble to charge my phone every night is a relief, especially when traveling.

The power of battery flexibility

The OnePlus 15’s impressive battery endurance is only half the story. The phone also supports blazing-fast 80W charging in the United States through a charger that, by the way, is included with the device (a rarity these days), meaning I can top it up incredibly quickly.

With just a few minutes of charging, I can gain enough battery to last me for an entire day. This is awesome because it means I don’t have to truly worry about my phone ever becoming useless. I just need to reach an outlet, any outlet, spend a couple of minutes there charging, and I have enough battery to keep going.

Based on my testing, it takes approximately 52 minutes to charge the OnePlus 15 to full. Due to the U.S. grid system, the device charges at a maximum 80W, though my measurements show a peak charging speed of 72.6W.

While other smartphones support fast charging, they require you to use it more frequently. By combining fast charging with a gargantuan battery, the OnePlus 15 offers the flexibility to skip charging entirely for a day or two, while still having the safety net of an instant top-up when needed.

A larger battery, but at what cost?

While I wish I could say the OnePlus 15 is simply a better version of the OnePlus 13 — a device that was virtually flawless for its price — it does make a few compromises, mostly due to cost-cutting.

As my colleagues have already noted, the display, vibration motor, and cameras are, on paper, downgrades. The display is lower-resolution but faster, a trade-off that only hardcore gamers playing a handful of titles will appreciate. The haptic motor has also been toned down a bit, providing weaker vibrations. The cameras no longer carry the signature Hasselblad branding and processing, instead using OnePlus’s own DetailMax engine.

Furthermore, the design is less inspired; the hardware looks closer to an iPhone, and OxygenOS 16 resembles the latest iOS release with its Liquid Glass-like UI elements. The operating system also has a few annoying issues that I would like to see OnePlus address.

First, I’m annoyed at its deployment of (thankfully optional) battery-saving features that restrict background apps. I still haven’t figured out how to get timely notifications from ProtonMail when using the OnePlus 15! Second, OxygenOS still shows me app notifications when Do Not Disturb mode is turned on, regardless of my settings! Despite these issues and the obvious iOS design inspiration, I’m still a big fan overall of OxygenOS 16.

And the same goes for the phone as a whole. Despite the on-paper downgrades, the OnePlus 15 is still a wonderful phone overall. The device is as fast and smooth as you’d expect from a phone with the Snapdragon 8 Elite Gen 5. The display remains crisp and bright, the vibration motor is still perfectly acceptable, and the camera quality is solid across all focal lengths, though its telephoto shots fall behind my preferred shooter, the Xiaomi 15 Ultra.

Will anyone else step up to the plate?

It’s difficult to find a flagship phone that’s genuinely bad these days. Almost any top-tier phone you pick up will be fine in most areas, but many have at least one noticeable flaw. What made the OnePlus 13 so exceptional wasn’t that it was merely “fine” overall — it was that it had no real flaws to speak of.

The OnePlus 15 doesn’t achieve excellence in quite the same way the OnePlus 13 did, but its breakthrough battery life is a standout feature strong enough to make it an excellent device. Had OnePlus simply improved on every aspect of the OnePlus 13, the OnePlus 15 might have been a shoo-in for phone of the year. It’s difficult to disregard the hardware downgrades, but thankfully, they don’t detract too much from the overall experience.

And thankfully for OnePlus, it seems no other smartphone company in North America is as interested in advancing battery life as it is, leaving the OnePlus 15 in a unique position. While other companies pursue smartphones that are thinner and lighter at the cost of battery life, OnePlus is betting that people are content with the size of existing smartphones but aren’t happy with how long they last. They’re betting that people don’t actually want to live with phones offering only a single day’s worth of power. They’re proving that smartphone battery life can evolve.

Samsung, Google, and Apple, I hope you’re watching, because the smartphone battery bar has just been raised significantly.