The VOOC 3.0 charging technology uses the D+/D- pins for the charger to communicate with the phone since USB Power Delivery is not used. We can see that there is increased D+ when VBUS voltage changes.
During the initial charging stage where battery charges from 0% to 85%, we can see that VBUS power peaks at 16.5W (below the 20W claimed by the technology) and gradually declines where VBUS voltage stays within a 4.5-5V range and current declines steadily.
It takes about 1.3 hours to charge the battery from 0% to 85%, where the VBUS power stays in a 10-16 watt range. It then takes another .6 hours to fully change the battery while VBUS power stays in a 5-7W range. The max temperature of the phone only reaches about 38 deg C.
While the phone's display is on, we can see that it only takes 1.9 hours to fully charge the battery from 0%. This charging performance is superior to the charging behavior seen with SuperVOOC 2.0 (click here for more info).
The OPPO Reno2 also supports USB Power Delivery but Oppo has chosen not to take advantage of this technology for fast charging. When we connect a USB PD charger to the OPPO Reno2, the phone only pulls 5W from the charger and takes much longer (~4.7 hours to fully charge to 100%).