Observing How OPPO's VOOC Charger Supports VOOC Flash Charging
Many smartphone companies go the extra mile to develop their own brand of fast charging technology for their phones as a marketing strategy, and OPPO is no exception. OPPO introduced the VOOC flash charging system through its VOOC Ultra Fast Charger that is supported by some of its newer phones like the OPPO R9s.
OPPO's VOOC (Voltage Open Loop Multi-step Constant-Current Charging) flash charging system claims to be able to charge up to 75% in just 30 minutes. The OPPO VOOC Ultra Fast Charger uses this technology to offer 20 watts (5 volts @ 4 amps) of rapid charging for supported OPPO phones.
The VOOC circuit technology reportedly increases charging speed and provides safer charging by lowering the temperature of the charging adapter and creating an interface from the adapter to the phone.
The charger cable has 6 pins in its micro-USB connector, with two pins allocated for V-Bus and another two for Ground to carry a current of 4 amps. The common D+ and D- pins are similar to the standard USB.
On the adapter portion, both the cable connection plug and adapter receptacle have 5 pins on each. Using a standard USB cable in general will not establish any fast charging communication between the OPPO R9s and OPPO VOOC Ultra Fast Charger, and the current will not go over 1.5 amps. The OPPO charger can only initiate D+ and D- communication with the phone when connected with its own charger cable due to an additional pin on the circuit.
Using an oscilloscope, we observed the maximum current drawn by the OPPO R9s from the OPPO VOOC Ultra Fast Charger is 3.6 amps while the phone was being charged on a fully drained battery.
The current can be seen to steadily drop as the phone's battery gets closer to being full. Note the phone's temperature remained below 34 degree Celsius during charging.
From the screens below, the OPPO charger is observed to charge the OPPO R9s to 40% in 20 minutes.
The OPPO charger managed to charge up to 97% in about an hour.
After 97% of charging, the OPPO VOOC Ultra Fast Charger took another 20 minutes to fully charge the OPPO R9s.