After five years of powering the action cameras on our Tour Easy recumbents, the pair of Anker A1215 PowerCore 13000 USB power banks have about 8 A·hr of capacity with a 2 A load after a full charge:
It seems I did not test them on arrival, so I have no idea what their original capacity might have been, but I’m certain it wasn’t the 13 A·hr implied by their name.
The sawtooth voltage output looks like the internal controller picks a constant boost (or buck) ratio based on the battery voltage, then adjusts it when the output voltage falls below the lower limit. You can imagine it desperately boosting the ratio as the battery voltage falls off a cliff near the end of the curve.
I have no idea why the two packs behave so differently, although the voltages are certainly within ordinary USB limits.
They’ll continue powering the camera on my bike for a while, after which I’m sure they’ll come in handy for something …
The Smell of Molten Projects in the Morning 