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Xiaomi's '100W' Quick Charging Goes From 0 To 100 In 17 Minutes (arstechnica.com)
Xiaomi is teasing a new 100W quick-charging solution for mobile phones that can fully charge a large 4,000mAh battery in just 17 minutes. Ars Technica reports: 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.
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.
Indeed! If charging Lipo batteries for RC cars has taught me anything, itâ(TM)s that the quicker to 100% charge, the quicker the battery is permanently toast.
Assuming it is a Li-ion battery- 3.6V nominal and 4Ah there was 14 Wh stored in the battery. The charger used about 80W over the time 17/60th of an hour- about 23 Wh provided- so 9Wh ends up as heat, using a conversion- that means about 32000 J.
To put this in perspective- 12oz of water is about 340g, and the specific heat of water is 4200 Joules per kilogram per degree Celsius (J/kgC) so... 32000 J /(.340 kg * 4200 J/kgC) = 22C (72F) - not an insignificant amount of heat. Not crazy though.