+500mA at best, so not particularly fast. There’s more to the article about conversion loss, but that’s the gist. Good for headphones, not much else.
Testing with a Samsung Galaxy S10+ and a Samsung Galaxy Note 8, both taken out of cases and placed back to back. Using 3C battery monitor to measure.
Battery on the Note 8 (chargee,) 55% at start, battery on the S10+ (charger,) was at 76%. Started test at 1:05, ended at 1:27. End results battery on the Note 8 (60%, 5%+) battery on the S10+ (65%, -11%)
S10+ battery=4400mAh, Note 8 battery = 3300mAh
So mathing I used 484mAh from the S10+ to give the Note 8 165mAh. 34% efficiency of transfer. That’s pretty low.
We generally figure 80% conversion ratio from S10+ battery to WiFi charging plate, 75 efficiency from charging plate (S10+) to receiver coil (Note 8), 80% efficiency from receiver coil to Note 8 battery taking it up. Should be getting +232mA, so somewhere there’s a missing 67mA in that transfer.
Charging speeds topped out at 500mA, so slow speed charging, and quite often were showing rates of around +222mA during the charge.
With Wireless Power Share you won’t be charging your friend’ phones fast, but it might be useful for the next gen WiFi charging headphones.