It's not often that you hear an audible gasp in the PhoneArena office, but that is exactly the reaction when we heard about the brand new Xiaomi Redmi Note 15 Pro.
The phone was just released in China and it's a $200 phone with an insane 7,000 mAh battery. And you would think, it would be a chunky, thick phone, right? But it's not. At just 7.8mm, it's thinner than the iPhone 16 Pro Max and the Galaxy S25 Ultra, both measuring around 8.2mm.
At 210 grams, it also weighs quite a bit less than the Pro Max or Ultra phones of today, and all while sporting a 6.83-inch screen, just as large as those pricier competitors.
Despite the massive battery size, the phone is remarkably thin at just 7.8mm
The interesting part is that Xiaomi does not specify whether it's even using the new silicon-carbon battery technology, or if this is a traditional battery.
But whatever the case, it is really impressive how Xiaomi can fit a 7,000 mAh battery in a slimmer and lighter body than the Galaxy S25 Ultra, which only has a 5,000 mAh battery. This is a massive 40% difference in battery size!
Does your phone double as a power bank with 22W reverse charging? This one does.
Xiaomi's official explanation is that "advanced packaging and stacking technologies have been upgraded to further increase battery capacity." And here are some more numbers that Apple and Samsung should copy:
Battery energy density reaches 835Wh/L on the Redmi Note 15 Pro
It achieves a breakthrough 2-day Days of Use battery life
The battery has a long lifespan of five years
Here is the best part — equipped with 22.5W wired reverse charging, this new Redmi phone doubles as a power bank.
Charging Speeds
Interestingly, the charging speed of the Redmi Note 15 Pro is 45 watts, slower than the 90W speeds supported by the higher-end Redmi Note 15 Pro Plus model (released a bit earlier).
Of course, there are always a few worried people in the comments, mentioning that Xiaomi phones typically also charge faster and how that might be a danger. There is no evidence to suggest that, despite years of super-fast Xiaomi phones being on the market.
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In the past few years, Xiaomi has developed its own battery management chip, the Xiaomi Surge G1, which monitors and manages charging speed, temperature, health, and power output.
This chip allows for optimized overnight charging and limiting the heat generated by fast charging, and consequently this helps slow down battery aging in the long term. In simple terms, this battery technology is safe and tested in time.
Specs
Everything else about the Redmi Note 15 Pro is quite ordinary, this is a fine-looking budget handset.
Here is a quick breakdown of the specs, in case you are interested:
6.8 OLED screen, 120Hz, 1280p
3,200 nits peak brightness
MediaTek Dimensity 7400-Ultra
50 MP main camera (Sony LYT-600)
8 MP ultra-wide
2 MP macro camera
20 MP front-facing cam
Starting from 8/256GB
IP69K water and dust protection
7,000 mAh battery
45W charging
The phone is only available in China right now, but it's still hard to shake off this unsettling feeling that we are missing out on some insane battery life with our current flagships. Here is to hoping we get those battery sizes sooner rather than later.
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Victor, a seasoned mobile technology expert, has spent over a decade at PhoneArena, exploring the depths of mobile photography and reviewing hundreds of smartphones across Android and iOS ecosystems. His passion for technology, coupled with his extensive knowledge of smartphone cameras and battery life, has positioned him as a leading voice in the mobile tech industry.
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