OnePlus 15 vs Galaxy S26 Ultra vs Galaxy S25 Ultra: Best for Battery?
OnePlus 15
6.78-inch phone with a 7,300mAh battery, 80W wired and 50W wireless charging, and security updates to November 2031.
Best for battery and fast charging
Galaxy S26 Ultra
6.9-inch QHD+ Ultra with a 5,000mAh battery, 60W wired charging, the S Pen, and security updates to February 2033.
Best for the longest update window and the S Pen
Galaxy S25 Ultra
6.9-inch Ultra with a 5,000mAh battery, the S Pen, and security updates to January 2032.
Best for One UI and the S Pen at an older-model price
Quick Answer
If battery life comes first, the OnePlus 15 has the biggest battery of the three: OnePlus lists 7,300mAh with 80W SUPERVOOC wired and 50W AIRVOOC wireless charging, against 5,000mAh on both Galaxy Ultras. If you want the longest update window, the S Pen, or to stay on One UI, pick a Galaxy Ultra. Samsung lists seven OS upgrades for both, with security updates to February 2033 on the S26 Ultra and January 2032 on the S25 Ultra. OnePlus lists security updates for the OnePlus 15 to November 13, 2031. Neither is better for everyone; it depends on whether battery or software and the S Pen matter more.
Compare next
Galaxy S26 vs Galaxy S26 Ultra
Full Comparison
| Attribute | OnePlus 15 |  Galaxy S26 Ultra |  Galaxy S25 Ultra |
|---|---|---|---|
| Battery | 7,300mAh(winner) | 5,000mAh | 5,000mAh |
| S Pen | No | Built in | Built in |
| Charging | 80W wired, 50W wireless(winner) | Up to 60W wired, 25W wireless | — |
| Display | 6.78-inch LTPO 1.5K, up to 165Hz | 6.9-inch QHD+ | 6.9-inch |
| Chip | Snapdragon 8 Elite Gen 5 | — | Snapdragon 8 Elite for Galaxy |
| Rear cameras | 50MP main, 50MP ultra wide, 50MP 3.5x periscope | 200MP wide, 50MP ultra wide, 10MP 3x, 50MP tele | 200MP wide |
| Software support | Security updates to 2031-11-13 | 7 OS upgrades, security to 2033-02(winner) | 7 OS upgrades, security to 2032-01 |
Battery
OnePlus 15
7,300mAh(winner)
Galaxy S26 Ultra
5,000mAh
Galaxy S25 Ultra
5,000mAh
S Pen
OnePlus 15
No
Galaxy S26 Ultra
Built in
Galaxy S25 Ultra
Built in
Charging
OnePlus 15
80W wired, 50W wireless(winner)
Galaxy S26 Ultra
Up to 60W wired, 25W wireless
Galaxy S25 Ultra
—
Display
OnePlus 15
6.78-inch LTPO 1.5K, up to 165Hz
Galaxy S26 Ultra
6.9-inch QHD+
Galaxy S25 Ultra
6.9-inch
Chip
OnePlus 15
Snapdragon 8 Elite Gen 5
Galaxy S26 Ultra
—
Galaxy S25 Ultra
Snapdragon 8 Elite for Galaxy
Rear cameras
OnePlus 15
50MP main, 50MP ultra wide, 50MP 3.5x periscope
Galaxy S26 Ultra
200MP wide, 50MP ultra wide, 10MP 3x, 50MP tele
Galaxy S25 Ultra
200MP wide
Software support
OnePlus 15
Security updates to 2031-11-13
Galaxy S26 Ultra
7 OS upgrades, security to 2033-02(winner)
Galaxy S25 Ultra
7 OS upgrades, security to 2032-01
Pros & Cons
12 pros·7 cons across both
OnePlus 15
Pros
Cons
Galaxy S26 Ultra
Pros
Cons
Galaxy S25 Ultra
Pros
Cons
Verdict
Best for battery and charging speed: OnePlus 15. 7,300mAh, 80W wired and 50W wireless, security updates to November 2031. Best for the longest update window and the S Pen: Galaxy S26 Ultra. Seven OS upgrades and security updates to February 2033, 60W wired. Best for Samsung software and the S Pen at an older-model price: Galaxy S25 Ultra. Seven OS upgrades and security updates to January 2032. Neither is better for everyone; it depends on whether battery or software and the S Pen matter more.
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Frequently Asked Questions
6 questions
On capacity, the OnePlus 15. OnePlus lists a 7,300mAh battery and up to 31 hours of video playback. Samsung lists 5,000mAh for both the Galaxy S26 Ultra and the Galaxy S25 Ultra, and up to 31 hours of video playback on the S25 Ultra. OnePlus also says the battery keeps 80 percent capacity after 4 years. That is OnePlus's own claim.
OnePlus lists security updates for the OnePlus 15 until November 13, 2031. That is about six years from launch, not two or three. OnePlus's general policy promises a minimum of three years of security updates for phones, and the OnePlus 15 date runs well past that.
Samsung lists seven major OS upgrades for both. The S26 Ultra launched on Android 16 and is listed up to Android 23, with security updates until February 2033. The S25 Ultra launched on Android 15 and is listed up to Android 22, with security updates until January 2032.
The OnePlus 15. OnePlus lists 80W SUPERVOOC wired charging, up to 100W with its 100W adapter, and 50W AIRVOOC wireless charging. Samsung lists up to 60W wired and up to 25W wireless for the Galaxy S26 Ultra.
No. The S Pen is built into the Galaxy S26 Ultra and the Galaxy S25 Ultra. If you will not use it, it should not decide the purchase.
Both have a 5,000mAh battery, a 6.9-inch screen, a 200MP main camera, and the S Pen. The S26 Ultra adds about a year of extra security support, to February 2033 against January 2032, and Samsung lists up to 60W wired charging for it. If the S25 Ultra is clearly cheaper and January 2032 covers your keep, it is the better value.
Analysis: OnePlus 15 vs Galaxy S26 Ultra vs Galaxy S25 Ultra
If you charge twice a day now, the OnePlus 15 has the most battery on paper. If you want the longest update window, the S Pen, or One UI with Galaxy Buds, pick a Galaxy Ultra. Neither is better for everyone; it depends on whether battery or software and the S Pen matter more.
Battery and charging
OnePlus lists a 7,300mAh battery for the OnePlus 15 and up to 31 hours of video playback. It charges at 80W SUPERVOOC wired, up to 100W with OnePlus's 100W adapter, and 50W AIRVOOC wireless. OnePlus also says the battery keeps 80 percent of its capacity after 4 years. Treat that as OnePlus's claim.
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Samsung lists 5,000mAh for both Galaxy Ultras. The S26 Ultra has Super Fast Charging 3.0 up to 60W wired and up to 25W wireless. Samsung lists up to 31 hours of video playback for the S25 Ultra. On capacity and charging speed, the OnePlus 15 leads.
Software support for a 4 to 5 year keep
Samsung's update policy lists seven major OS upgrades for both Ultras. The Galaxy S26 Ultra launched in February 2026 on Android 16 and is listed up to Android 23, with security updates until February 2033. The Galaxy S25 Ultra launched in January 2025 on Android 15 and is listed up to Android 22, with security updates until January 2032.
OnePlus lists security updates for the OnePlus 15 until November 13, 2031. It launched on OxygenOS 16, based on Android 16. That date is well past a 4 to 5 year keep, so any of the three covers it. OnePlus has not published a number of major OS upgrades for the OnePlus 15.
Display
The OnePlus 15 has a 6.78-inch LTPO 1.5K display with refresh up to 165Hz. Both Galaxy Ultras have a 6.9-inch screen, and the S26 Ultra is QHD+. If 120Hz is smooth enough for you, the display should not decide it.
Chip
OnePlus lists the Snapdragon 8 Elite Gen 5 for the OnePlus 15. Samsung lists the Snapdragon 8 Elite for Galaxy for the S25 Ultra. Chip names alone are not a speed ranking.
Cameras
The OnePlus 15 has three 50MP rear cameras: a main camera, an ultra wide with a 112-degree field of view, and a periscope telephoto with 3.5x optical zoom. The Galaxy S26 Ultra has a 200MP wide, a 50MP ultra wide, a 10MP 3x telephoto, and a 50MP telephoto with up to 100x Space Zoom, plus a 12MP selfie camera. The S25 Ultra also has a 200MP wide camera and a 12MP front camera.
S Pen and ecosystem
The S Pen is built into both Galaxy Ultras. The OnePlus 15 has no stylus. If you already use One UI and Galaxy Buds, staying on Samsung keeps that setup the same.
S25 Ultra or S26 Ultra
Both have a 5,000mAh battery, a 6.9-inch screen, a 200MP main camera, and the S Pen. The S26 Ultra adds about a year of security support and Samsung's listed 60W wired charging. If the S25 Ultra is clearly cheaper and January 2032 is long enough, it is the value pick.
Who should buy which
Choose the OnePlus 15 if battery and fast charging are the reason you are upgrading, and you are open to OxygenOS.
Choose the Galaxy S26 Ultra if you want the longest update window, the S Pen, and the newest Samsung cameras.
Choose the Galaxy S25 Ultra if you want One UI and the S Pen for less, and security updates to January 2032 are enough.
Resources & Learn More
Curated sources to dive deeper
Where to Buy
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Wikipedia
- W
OnePlus 15 on Wikipedia (opens in new tab)
6.78-inch phone with a 7,300mAh battery, 80W wired and 50W wireless charging, and security updates to November 2031.
- W
Galaxy S26 Ultra on Wikipedia (opens in new tab)
6.9-inch QHD+ Ultra with a 5,000mAh battery, 60W wired charging, the S Pen, and security updates to February 2033.
External Resources
OnePlus 15 (opens in new tab)
7,300mAh, 80W wired, 50W wireless, 165Hz, Snapdragon 8 Elite Gen 5.
OnePlus security update period (opens in new tab)
OnePlus 15 security updates until 2031-11-13.
Samsung Galaxy S26 series compare (opens in new tab)
S26 Ultra 5,000mAh, 60W wired, 6.9-inch QHD+, cameras, S Pen.
Samsung Galaxy S25 Ultra (opens in new tab)
5,000mAh, up to 31 hours video, Snapdragon 8 Elite for Galaxy.
Samsung update policy (opens in new tab)
Seven OS upgrades; security to 2032-01 (S25 Ultra) and 2033-02 (S26 Ultra).
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