OnePlus 15T vs Xiaomi 13 Ultra

OnePlus 15T

Snapdragon 8 Elite Gen 5 paired with 12-16GB LPDDR5X Ultra Pro RAM delivers flagship synthetic scores — Notebookcheck recorded Geekbench multi-core 10,976 and 3DMark Wild Life Unlimited 29,901, on par with the larger Xiaomi 17 and Honor Magic8 Pro Air. The problem is sustained: in the 3DMark Wild Life stress test the GPU drops over 50% and the back of the phone hits 50 °C, which both Notebookcheck and SuperSaf flag as a deal-breaker for long gaming sessions.

• Geekbench 6 multi-core hits 10,976 — flagship-tier and within 1% of the average 8 Elite Gen 5 result, so there is no compromise on the chipset versus larger phones.
• 3DMark Wild Life Unlimited hits 29,901 — 5% above the 8 Elite Gen 5 average and ahead of the Xiaomi 17 with the same chip.
• In the 3DMark stress tests the OnePlus 15T shows a sharp drop in performance of over 50%, which significantly lowers our rating.
• Wildlife Extreme stress test scores swung from 6,990 best loop to 3,743 worst loop in a single run — the chart is 'quite a bit of a bumpy ride' and performance mode did nothing to stabilize it.
• Surface temperatures hit 48.3 °C on the back during stress testing and continued climbing to 50 °C near the camera bump — about 45 °C internal — which seems to be the phone's thermal limit.
• Genshin Impact averaged 60.3 fps over 30 minutes at just 3.2 W power draw, with the phone staying cool to the touch — and Peacekeeper Elite pushed 164.5 fps thanks to native 165 Hz support.
• r/Android's reviewer thread flags the same thermal issue directly: 'Gets kinda hot, over 50 degrees in the corner. This is with its very heavy throttling.'

Xiaomi 13 Ultra

Snapdragon 8 Gen 2 + 16GB RAM delivers flagship-class performance with strong thermal headroom — Xiaomi's tune is among the best of 2023 SD 8 Gen 2 phones for sustained tasks.

• Snapdragon 8 Gen 2 + 16GB RAM + 512GB UFS 4.0 storage — top-tier 2023 silicon and the most RAM of any flagship phone.
• Wired: 'a smooth operator' with Snapdragon 8 Gen 2 + 12GB RAM (global variant) — no real-world performance complaints.

OnePlus 15T

This is the section the OnePlus 15T was built to win. The 7,500 mAh silicon-carbon 'Glacier' cell is the largest ever fitted to a true compact phone — 50% bigger than the iPhone 17's pack in a similar footprint. Notebookcheck measured roughly 1.5 days of real-world endurance at 150 cd/m². Wired charging tops out at 100 W, wireless at 50 W. The only friction points are the missing built-in magnets for MagSafe-style alignment and the still-USB-2.0 port.

• OnePlus relies on a silicon-carbon-based battery with a large capacity of 7,500 mAh for its mini flagship — in our practical battery test at 150 cd/m² brightness, the 15T achieved an excellent battery life of nearly 1.5 days.
• 9to5Google's preview confirms the 7,500 mAh cell carries the same 'Glacier' moniker as the OnePlus 15's battery, so the silicon-carbon structure is here too — 200 mAh more than the larger sibling.
• Even though the phone keeps the same compact size, it now packs a massive 7,500 mAh battery — to put that into perspective, the iPhone 17 Pro Max only has around 5,000 mAh, and this is a 6.32-inch phone.
• Battery life is wild for a phone this size and is actually a hair bigger than the one in the OnePlus 15, which has a noticeably larger footprint.
• 100W SuperVOOC wired charging and 50W wireless mean even the huge cell refills fast — getting through two full days on a single charge feels totally realistic.
• There is no native magnetic Qi alignment — wireless charging works, but accessories require a separate magnetic case for MagSafe-style snap-on functionality.
• r/Android's reaction to the battery is unambiguous — 'Incredible battery life makes the compact smartphone competition pale in comparison' is the actual review-thread headline.

Xiaomi 13 Ultra

5,000mAh battery + class-leading 90W wired and 50W wireless charging — Reddit's drain shootout placed it ahead of S22 Ultra, OnePlus 11, and Pixel 7 Pro at 10h 26min total SOT.

• 5,000mAh battery + 90W wired (full in ~35 min per Xiaomi) + 50W wireless (full in ~49 min) + 10W reverse wireless.
• Wired charge test: 34% to 63% in just 10 minutes — fantastic real-world charging speed.
• GSMArena endurance: 15h 29min web browsing, 19h 13min video looping — par with Find X6 Pro, ahead of Vivo X90 Pro.
• Reddit drain shootout: 10h 26min total SOT — beat S22 Ultra (9h 43m) and OnePlus 11 (10h 16m); narrowly beaten by S23 Ultra (11h 15m) and iPhone 14 Pro Max (11h 25m).
• Camera-heavy use drains battery noticeably faster per r/Android — the photography workflow is the biggest endurance hit.