We all know battery density hasn’t kept pace with the power demands of smartphones, but would you settle for a smartphone that just charged really, really quickly? Xiaomi is teasing a new high mark for speedy phone charging: a “100W” quick-charge solution. Xiaomi Senior Vice President Xiang Wang shared a video on Facebook of the new charging solution in action, saying that “Xiaomi’s engineers have created a 100W fast-charging solution, which can fully charge a large 4000mAh battery in just 17 minutes!”
The video shows a charging race between two phones, Xiaomi’s unnamed “100W” prototype and a phone with “50W” charging from “Brand O”, which looks like it’s an Oppo RX17 Pro. I put both of these wattage ratings in quotations because neither phone actually hits its rated charging speed. Xiaomi’s video shows a live, in-line power reading, and the “100W” charging shows a sustained ~80W (18V / 4.5A) from about 5-30 percent, with a peak of 88W. The competing 50W Oppo quick-charge solution caps out at around 40W.
Branding aside, what matters is the actual charging speed, and Xiaomi’s ability to fully charge a phone battery in 17 minutes is impressive. The test stops when the Xiaomi phone fills up, leaving the Oppo battery stuck at a mere 65 percent. Considering that Xiaomi was charging a 4000mAh battery and that Oppo only had a 3700mAh battery, Xiaomi’s solution is about 1.6 times faster than Oppo’s quick charge, which is currently the fastest charging scheme on the market.
Unfortunately, Xiaomi didn’t offer any specifics on how its charging solution works. Dissipating heat, which slows charging and degrades the life of a battery, is a major concern when charging this quickly. Oppo’s charging solution (branded “Super VOOC” in Oppo phones and “Dash Charging” in OnePlus phones) solves this issue by duplicating the heat-generating power management circuitry inside its proprietary power brick. If you are using a non-Oppo phone charger, the phone’s internal power management circuitry will do its best to do all the usual power conversion, but this heats up the battery. If you’re using a proprietary Oppo charger, the phone circuitry can shut off, and all that heat generation occurs in the power brick, far away from the battery. It would not surprise me to hear Xiaomi is doing something similar.
So far this is only a demo, but Xiaomi is known for aggressively adopting new technology in its devices, so be on the lookout for 100W charging in Xiaomi’s next flagship. Xiaomi’s non-Chinese competition really isn’t keeping pace with a technology like this. The iPhone XS and Pixel 3 can only do 18W quick charging, while the Galaxy S10 tops out at 15W.
