Battery charging is one of the few remaining segments in the smartphone world where proprietary technologies can thrive. Most companies use chipsets from the same vendors, they also buy the same monitors and camera sensors. But the batteries and included hardware are sometimes completely customizable and have been a field of rapid innovation for the past few years.
Okay, USB Power Delivery exists, some might say it’s the best option because of its wide support. The same argument can be made for Qi on the wireless charging front. But right now, proprietary systems allow for higher speeds and are used on some unique devices.
A simplified chart of how fast charging systems do what they do
This week we wanted to look at how battery and charging technology has evolved over the last decade and we will focus on Xiaomi. We will mostly look at averages, but we have also included maximum values as they also tell an interesting story.
We often hear people say “give me a big battery even though the phone is thick”. For better or worse, neither Xiaomi nor other smartphone manufacturers seem to agree with that sentiment. As you can see, the average thickness of Xiaomi phones dropped steadily for a while and then stabilized around 9mm. However, the average battery capacity still increased over time thanks to technology improvements.
These ever-larger batteries would require more and more time to charge at the 10W USB baseline, so something had to be changed. The first fast charger phone from Xiaomi was the Mi 3 (2013), which utilized Qualcomm’s Quick Charge 2.0 to handle 18W. In fact, Xiaomi used QC for many of its phones. For example, the Mi 9 Pro (2019) included QC 4+ and did 40W wired and 30W wireless charging.
But Quick Charge could not keep up, and the Xiaomi phones with the highest charging ratings have switched over to a proprietary solution. As we mentioned in the opening, it is one of the areas where companies can stand out with in-house technology, e.g. Surge P1 charging ships.
Battery capacity did not grow indefinitely. A few years ago, Xiaomi had a Mi Max series that had large screens and large batteries. The other model had a 6.44 ”screen and a 5,300 mAh battery. The third went up to 6.9 ”and 5,500 mAh. But those were not the biggest batteries from the company, no. Instead, phones like the affordable and not-too-large Poco M3 pack 6,000 mAh batteries (M3 measures 162.3×77.3×9.6 mm and weighs 198g). 6,000 mAh is as high as Xiaomi has ever received.
A few interesting things we noticed as we dug through the data. Mi Mix 2S from 2018 was the first Xiaomi to support wireless charging, it was rated at 7.5W. The company also released its first official Qi charger with the phone. Mi Mix 3 from the same year went a little faster with 10W support.
And it took off from there – 30W in 2019, then 50W, then 67W, so … nothing. At least not yet. But we’m halfway through the year, and Xiaomi has yet to release a new phone that supports wireless charging.
What happened? Mi 11 Ultra brought parity between cable and wireless charging – both rated at 67W. Of course, the cable charging is more efficient, but not as much as you might think. If you compare the cable vs. wireless, 0-100% charging time is 36 minutes and 39 minutes.
Still, the company’s focus seems to have shifted toward wired charging. Phones like the Xiaomi 11i HyperCharge 5G only exist to allow users super-fast 120W charging – a full 0-100% charge was completed in 16 minutes in our test. 22 minutes if you turned off Boost mode to drain the battery easily. Meanwhile, only a handful of models released in the last few years support 50W wireless charging or higher.
How fast can charging technology go? As for the USB-C cable, there is a lot of ground clearance. The latest USB Power Delivery specification offers a full 240W. Xiaomi even introduced a 200W charger a year ago. And it has an 80W wireless charger. We expect to see tax rates continue to rise for at least a few more years, especially the average tax rate.