And in addition to what Marcus has said about Euler power, another thing to remember (I have to repeat this again as I can't be certain from your post that you'd done it) is that if you do NOT connect the middle/temperature sense of the battery via a 10k resistor to GND (or via a 10K thermistor), the pine64 will NOT charge the battery. And even when it does charge, it seems to charge very slowly - my board always charges at around 400ma (unless I am a bit sneaky about starting it with no SD card to make it just charge using defaults)... so a completely flat 2000 mah battery probably take over 5 hours to charge...
What happens if you download and run this script? What does it report about your battery?
What happens if you download and run this script? What does it report about your battery?