Flash appears to have a fast discharge rate. Why is this?
To make the LED indicator more accurate, 0% - 50% is 80% of the battery's capacity (16,000mAh) and the last 20% is 51% - 100% (4,000mAh). This means it's really normal for the battery to appear that it's discharging quickly. The LED indicator is based on charging time and not capacity, which is why its designed this way.