Why reviewers can't drain the OnePlus 15's 7,300mAh battery in a day

Marques Brownlee, reviewing as MKBHD, described a night most flagship owners would not risk. He finished a day around 50 percent, left the OnePlus 15 off the charger, and woke up looking at 49 percent, "ready for a whole another day." That is not a slogan. It is a 7,300mAh silicon-carbon pack doing the thing US Galaxy, Pixel and iPhone buyers still do not get: making the bedtime plug feel optional.

OnePlus sold the phone as a 165Hz gaming flagship. 91mobiles, in a November 2025 piece built around living with it, argued the cell was the part that actually changed the week. Typical mixed usage — messaging, video streaming, browsing, location services, light gaming, photography — ended the day at 40 to 50 percent. The 165fps pitch looks loud on a thumbnail. The leftover battery is what people notice after they stop trying to kill it.

Tom's Guide's continuous 5G web-surfing test, the same one the site uses to rank every phone it reviews, lasted "an absolutely insane 25 hours and 13 minutes." The presenter crowned it the best phone for battery life the lab had ranked, and said he was averaging two days and 11 hours of ordinary use on a full charge. The iPhone 17 Pro Max managed 17 hours 54 minutes in the same routine. The Galaxy S25 Ultra lasted 14 hours 27 minutes.

Linus Tech Tips' ShortCircuit desk ran its own drain test twice to check for a fluke. "The OnePlus 15 gets 29 hours in our battery test. Compare that to the 20 hours of our OnePlus 13." GSMArena's Active Use Score hit 23 hours 7 minutes, the top of that chart at review time. The one bench that keeps the phone honest is PCMark: 91mobiles clocked 17.1 hours against 16.0 for the Oppo Find X9 Pro and 11.4 for the OnePlus 13. mAh is not a religion. A 7,500mAh rival lands within an hour of it on the right workload. The gap that keeps repeating is the one against what Americans can actually buy.

The Verge's Allison Johnson treated the capacity as a dare. She maxed the display settings and still finished two days with no overnight charge, nearly nine hours of screen time, and 32 percent left. WIRED's Julian Chokkattu left it on the nightstand unplugged and logged 10.5 hours of screen-on time across two days. These are not identical methods. They describe the same habit: you stop hunting for a socket.

The US product page is blunt about the ceiling. OnePlus lists 80W SUPERVOOC in the box, 50W AIRVOOC wireless, and "up to 100W" only with the optional dual-port GaN adapter. ShortCircuit's unboxing put a voltage asterisk on the bigger number: the same SuperVOOC brick "charges 120 watts on 240 volt and 80 watts on 120 volt." GSMArena's global sample, running the 120W charger, still peaked around 77W at the phone, reached 78 percent in 30 minutes, and filled in 41 minutes. On a 55W USB Power Delivery PPS adapter the same lab recorded 68 percent in half an hour and a 50-minute full charge.

US testers land in a similar neighborhood with the included 80W pack. WIRED went from 15 to 80 percent in 30 minutes, with 50 percent in 15. Johnson plugged in at 17 percent and hit 60 percent in 20 minutes, which she called easily a day's worth of power; on a standard USB-PD charger she measured a less blistering 36W. The brick still ships in the box, with the red USB-A SuperVOOC cable MKBHD called "sadly also not normal." Third-party USB-C PD works. It is just slower.

Wireless is the real US compromise. The phone does 50W only on OnePlus's AirVOOC pad, a separate purchase. It is ordinary Qi without built-in magnets — not Qi2, and, as WIRED put it, not even Qi2 Ready. OnePlus sells magnetic cases as a salve; The Verge measured up to 11W on a Qi2 charger with one fitted. ShortCircuit's charging test skipped the proprietary brick entirely and used a generic 45W USB-C charger: about 1 hour 20 minutes empty to full, roughly 20 minutes better than the Galaxy S25 Edge on the same protocol. If you live on MagSafe pucks, this is the wrong phone. If you keep the red cable in a bag, the refill is the point of the hardware.

OnePlus calls the pack Silicon NanoStack and markets it as the biggest battery in a consumer smartphone in North America, with what it says is the market's highest silicon percentage — 15 percent silicon inside the silicon-carbon. ShortCircuit noted it is a dual-cell design. The company claims the phone maintains 80 percent capacity after four years. MKBHD's practical translation: limit it to 85 percent charge and "it would still have more battery than the Galaxy S25 Ultra." OxygenOS backs that with Smart Charging, a charge limit adjustable in 5 percent steps between 80 and 100 percent, and bypass charging, which feeds a plugged-in game from the wall instead of the cell. GSMArena files those under battery health. ShortCircuit liked bypass for the same reason: less heat while the battery sits still.

The Verge's caution is the one US buyers should actually read. Johnson noted that silicon-carbon cells "tend to degrade faster than their lithium-ion counterparts," which she gave as the reason US manufacturers have been hesitant to adopt them. OnePlus's four-year, 80 percent claim is the company's answer, not an independent aging study — and The Verge found no specific battery-replacement option in OnePlus's US repair service, with a 12-to-15-workday turnaround. 91mobiles, after living with the phone, still put the camera behind the endurance: if photography is the job, buy something else. If the job is not opening the charger drawer, this is the flagship that keeps winning that argument.