USB-C fast charging is still a nightmare, but this phone finally gets it right

My thoughts on the state of USB-C and gadget fast charging are well documented by now; an interoperability nightmare that causes not just a headache for users but has also spun a web for manufacturers that few have successfully untangled. The problem is multifaceted: the overabundance of charging protocols (both proprietary and standardized universal) and battery health considerations make fast charging incredibly difficult to implement properly.

After years of trying to match chargers and cables with gadgets, I’d given up on anyone building a project that can work with all this legacy mess. At least that’s what I thought until I spent a couple of weeks getting to know the new Xiaomi 17 Ultra.

In fairness, Xiaomi has done fast charging reasonably well for some time already. Its proprietary HyperCharge plugs are blazingly fast and temperature-aware, which is a good thing. However, they still ship with an outdated USB-A cable for some reason. Still, its high-end phones support universal standards, including China’s Unified Fast Charging Standard (UFCS) and the broader USB Power Delivery (USB PD) specifications, with support for up to 90W on last year’s Ultra flagship and up to 100W on the latest flagship model I’ve tested.

The fact that you can fast-charge the Xiaomi 17 Ultra as quickly as possible with a wide array of plugs is gold-star-worthy. Given that major Western brands often barely sustain moderate power levels with a single fast-charging protocol, Xiaomi’s fast-charging capabilities truly put Apple, Google, Samsung (the new Galaxy S26 Ultra only just introduced support for 60W), and a few others to shame, especially given its now charging a huge 6,000mAh Si-C battery.

But that’s not what’s really impressed me about the Xiaomi 17 Ultra; this sort of stuff should be the bare minimum by now, and the phone’s unbelievably speedy top-ups are impressive but hardly new. Instead, the way Xiaomi presents options and interacts with us users has shown me exactly how the entire ecosystem should handle fast wired and wireless charging.

For instance, plug your phone in when it’s below 20% battery, and Xiaomi’s HyperOS asks if you’d like to enable boost mode to top up to 30% faster. HONOR debuted a similar feature last year, and I really liked it then, too. This enables the phone’s Top Speed wired charging option, which you can also manually enable in the settings menu whenever you like. All this really does is throw caution to the wind when it comes to temperature management, allowing the phone to charge a bit quicker than with the Standard option. Handy when you’re short on top-up time, as I often am.

Likewise, the phone prompts you with a notification to quickly disable Boost/Top Speed when you’re charging with a fuller battery. This encourages us to revert to a healthier charging power level when the battery already has plenty of juice, ensuring that your top-ups don’t unnecessarily shorten the battery’s lifespan.

There’s also a Smart charging option tucked in the settings menu. This claims to dynamically adjust the power level to keep the device cooler and therefore more responsive while you’re fast charging the phone. I noticed a pop-up appear when charging shortly after a gaming session, suggesting it was doing its job and trying to keep temperatures lower. Most phones perform similar throttling, but it’s nice to see a notification prompt that lets me pick. I can’t really think of many instances when you’d want to turn it off, aside from perhaps one final quick top-up before leaving the house.

Another, more subtle feature is that, regardless of which charging mode you’ve picked, the Xiaomi 17 Ultra reaches its maximum power levels only when the phone is at rest and the screen is off. It’ll still charge your phone while you use it, just not at super high power levels, which again assists with temperature control with the added comfort of ensuring your phone doesn’t warm up while it’s in your hands.

The exact power level depends on the battery’s charge, whether you’re in Top Speed mode, and how much you’re using the phone. I saw power levels ranging from 15W to 50W with the screen on. When actively using the phone, the power level can quickly drop to 20W or lower, though Top Speed mode tries to keep it a little higher. In any case, only when turning the screen off did the phone reach its maximum 70W of power draw from a 100W-capable plug.

While it might seem counterintuitive to reduce power while using the phone, this is good for battery health. Fast charging generates heat, but so does just using your phone, especially for intensive tasks like gaming or capturing 4K60 video. If you want your battery to last a long time, you need to keep it at a reasonable temperature, so Xiaomi makes sure to charge your phone a bit more conservatively when you’re using it.

As someone who often finds myself in situations where I need to top up as quickly as possible but certainly doesn’t want to fork out a small fortune on battery replacements in a couple of years’ time, Xiaomi’s approach strikes the perfect balance of options and safety. Especially when paired with more common features, such as an 80% battery charging limit, which the Xiaomi 17 series thankfully supports by default.

All that said, I don’t think Xiaomi’s fast-charging software implementation is quite perfect. For starters, the phone displays a nice “90W Quick Charging” prompt when plugged into one of its own chargers, but doesn’t for equivalently fast USB PD sources.

Not that this is a huge deal, and perhaps there’s something in Xiaomi’s proprietary protocol that makes this easier to implement. Still, it would be a very nice touch that would really help remove the opacity of fast-charging protocols and let users know for sure that their plug is optimally fast-charging their handset. Sadly, the lockscreen displays a rather misleading “Mi Turbo Charge” graphic when I power the phone via a 100W USB PD PPS charger, which makes no sense whatsoever.

Xiaomi is also missing a key feature that I really like on other phones: bypass charging. This is a very handy feature to keep temperatures under control during gaming sessions, for example. While Xiaomi’s temperature- and use-aware approach will help, bypassing the battery entirely is simply better in some situations.

Overall, the Xiaomi 17 Ultra supports top-tier fast charging protocols, offers a wealth of battery health features, and provides ample customization options to tailor the setup to your liking. While it’s not perfect, this is undoubtedly as close as anyone has come to making it effortless for users to achieve the fastest charging speeds while supporting long-term battery health.

Finally, someone has cracked the USB-C fast charging formula. Now we’ll just have to wait another decade for everyone else to catch up. I’m looking at you, Apple and Google.