The Anker PowerCore+ 26800mAh PD with 27W PD Portable Charger Bundle has both a USB Power Delivery based portable battery as well as a USB Power Delivery charger to supply power to other USB Type-C based phones, tablets, and notebook PC's. Let's see how well the 30 watts based portable battery portion charges the Samsung Galaxy A5 phone which supports fast charging using Samsung's proprietary quick charging scheme as well as USB Power Delivery over the USB Type-C interface.
From the USB Power Delivery negotiations, we can see how charging happens between the Anker battery charger and the Samsung Galaxy A5 on a 46% full battery. When directly connected with a USB Type-C to Type-C cable, the charger can be seen to offer an initial 15 watts (5 volts @ 3 amps) and 30 watts (15 volts @ 2 amps) charging power to the Samsung phone.
Later we can also see that the Anker battery charger displays the following power profiles: 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), 30 watts (12 volts @ 2.5 amps), 30 watts (15 volts @ 2 amps), and 25 watts (20 volts @ 1.25 amps). Oddly Anker did not mention 30 watts (12 volts @ 2.5 amps) on its casing.
Starting at a 46% battery, the Samsung Galaxy A5 actually pulls around 6.5 watts (5.2 volts @ 1.25 amps) while the phone is being used. The current then starts to get inconsistent between 1 to 1.25 amps @ 5.2 volts which at one time even peaks to near 2 amps for only a couple seconds. While we didn't manage to see the current reaching close to 3 amps, the Samsung Galaxy A5 can still charge with the Anker PowerCore+ 26800mAh PD at a similar power to the Samsung's Adaptive Fast Charging Charger while the phone is being used.