The OnePlus 15 ships with a 7,500 mAh silicon-carbon cell — one of the largest batteries we've put through our standardized smartphone test rig. Over 30 days of mixed use we measured screen-on time, idle drain, charge-cycle behavior, and thermal throttling on 120 W SuperVOOC.
Methodology
Each day followed a fixed pattern:
- Morning (9:00–12:00): 90 minutes Wi-Fi browsing + 30 minutes 5G video playback at 50% brightness
- Midday (12:00–14:00): Idle, screen off, push notifications active
- Afternoon (14:00–18:00): 60 minutes navigation (GPS + 5G) + 60 minutes light gaming (Genshin Impact, 60 fps cap)
- Evening (18:00–23:00): Mixed social + camera + reading
- Night: Charge from whatever level the phone hit by 23:00
Charging was always 120 W SuperVOOC unless noted. Ambient: 22–24 °C.
Screen-on time
| Week | Average SoT | Peak SoT | Days off charger > 24h |
|---|---|---|---|
| 1 | 9.1 h | 11.4 h | 3 |
| 2 | 9.4 h | 12.0 h | 4 |
| 3 | 8.9 h | 11.1 h | 2 |
| 4 | 9.2 h | 11.7 h | 3 |
Average across the month: 9.15 hours of screen-on time per charge cycle, with peaks above 12 hours on light-use days. For context, this is the highest SoT figure we've seen on any 2026 flagship to date.
Charging behavior
120 W SuperVOOC charges the OnePlus 15 from 5% to 100% in 31 minutes 18 seconds on average. The included charger throttled twice during the test (both times at ambient ~26 °C) — final 10% slowed to ~25 W and added roughly 6 minutes to the total.
Wireless charging on a 50 W AirVOOC pad reached 100% in 67 minutes from 5%.
Cycle health
After 30 days and an average of one full cycle per day, the reported battery health was 100% in OnePlus's own diagnostic tool. We'll re-test at 6 months and 12 months and update this report.
Verdict
The 7,500 mAh cell delivers on its promise. If you're comparing the OnePlus 15 against an iPhone 17 or a Galaxy S26 Ultra, battery is the spec where it most decisively leads — see the full OnePlus 15 vs iPhone 17 and OnePlus 15 vs Galaxy S26 Ultra breakdowns for everything else.