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In a previous review, we saw how Xiaomi has achieved best in class charging performance with the Mi 9 Pro 5G using USB Power Delivery (PD) technology (albeit through an unconventional USB Type-A based Xiaomi 45W QC3 charger that supports USB PD 3.0 based PPS). Let's see how the Mi 9 Pro 5G brings Qi wireless charging performance to a range previously only addressable through USB PD.

As in the case with the Xiaomi 45W QC3 charger, faster Qi charging on the Mi 9 Pro 5G is only possible with Xiaomi's own 30W Qi Wireless Charging Stand.

Again, we use the GRL-C2 USB PD Tester and GRL-PSP Power Analyzer software from Granite River Labs to analyze the details on how the Mi 9 Pro 5G works with the Qi chargers and the USB chargers powering them.

When the Mi 9 Pro 5G is fully drained and kept off, we connect the phone to the Xiaomi 30W Qi Wireless Charging Stand which is connected to the Xiaomi 45W QC3 charger sold with the Qi stand. Note the Xiaomi 30W Qi Wireless Charging Stand only uses Qualcomm Quick Charge technology to communicate with the Xiaomi 45W QC3 charger even though USB PD communication is possible using Xiaomi's special 5A USB Type-A to Type-C cable, and the Xiaomi 45W QC3 charger supports USB PD 3.0 PPS.

During the “Fast Charge” mode, the Qi stand consumes around 33W while during the “Cool Down” mode, the Qi stand consumes either at around 23W or 15W levels with the phone's external temperature (which is recorded using a FLIR camera) increasing by 17° C. Finally, in “Saturation” mode the Qi stand gradually pulls less power until the phone’s battery reaches 100%. Note that after 100% battery, the Qi stand still continues to pull 2.5W from the charger.

We now repeat the same testing and analysis, but this time with the Mi 9 Pro 5G drained to 1% and with the display and WI-FI kept active. Here, we see that during the “Fast Charge” mode, the Qi stand consumes around 33W before going into a “Cool Down” mode where power stays at either around 23W or 15W levels, with max temperature increase of 17° C. In "Saturation" mode, the Qi stand steadily reduces the power drawn but even after the battery has reached 100% charge, with the display and WI-FI kept active, the stand is consuming about 10W dropping down to 7W.

Comparing how the Mi 9 Pro 5G charges when the phone is off versus when the display and WI-FI are kept active, we can see that the phone charges slightly faster and warmer as it pulls overall similar levels of power when off. When off, the Mi 9 Pro 5G charges in about 78 minutes versus 85 minutes when the phone's display and WI-FI are kept active.

If we compare the Mi 9 Pro 5G's charging performance between using the Xiaomi 30W Qi Wireless Charging Stand versus the previous generation Xiaomi 20W Qi Wireless Charger, we can see that the 30W Qi version charges over 30% faster (measured when the phone's display is at full brightness).

Comparing the Mi 9 Pro 5G while off charging using the Xiaomi 45W QC3 charger versus the Xiaomi 30W Qi Wireless Charging Stand, we can see that the phone charges in 62 minutes versus 78 minutes respectively.

Comparing the Mi 9 Pro 5G while the phone's display and WI-FI are kept active, charging using the Xiaomi 45W QC3 charger versus the Xiaomi 30W Qi Wireless Charging Stand, we can see that the phone charges in 72 minutes versus 77 minutes respectively. We also observe very reasonable temperature increases with Qi which are not too far off from the temperature increases seen using USB PD.  

Usually we observe much slower charging times for Qi in general compared to USB PD, especially when the phones are kept active, but the Mi 9 Pro 5G has broken this rule by achieving much closer parity between both charging technologies. Although the Mi 9 Pro 5G only achieves this performance with the Xiaomi 30W Qi Wireless Charging Stand right now, we get a peep into the future where users achieve the same fast charging rates with either wired USB PD or Qi wireless charging technologies.