The VOOC 4.0 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- activity when USB VBUS voltage changes.
During the first 2 minutes of charging, we see that VBUS power peaks briefly at 21W (below the 30W claimed by the technology). Subsequently, VBUS power drops to 8-9W for about 1 hour, which is low for fast charging.
The initial fast charging period lasts for about 1 hour, reaching 50% battery. Afterwards, charging power drops to about 5W to complete charging to 100%. Overall, it takes about 3 hours to completely charge the battery from 0% to 100%. Due to this lower power and slower charging behavior, the max temperature of the phone only reaches about 30 deg C.
While the phone's display is on and under max brightness settings, we can see that it takes about 5.3 hours to fully discharge the battery but takes about 3 hours to fully charge the battery. This charging performance is superior to the charging behavior seen with SuperVOOC 2.0 (click here for more info).