I’ve had this power bank for a few years - it was given to me as a freebie at an event. I’ve no idea what the manufacturer is, or the capacity of the power bank. The review isn’t good, but it was a good test.
The first failure
11 minutes in to the capacity test the power bank started jumping between 5V and 3V:
As I’m not sure what the expected current from this is, I reduced the load to 0.5V, but this means that it’s not suited to charging a modern smartphone.
This powerbank does not neatly cut the power off as the cell empties, but the voltage gently reduces. The boost converter makes an annoying high pitched whine at this point…
It’s not a good power bank, but it was free. The cable that comes with it is useless, and will lose ~15% of the power being transferred. Expected capacity unknown, but it measured at 1162 mAh at 5V, which translates 1570 mAh at 3.7 as the manufacturers usually claim.