Keeppower 21700 5000mAh P5150TC (White-Blue) 2020
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Official specifications:
- Voltage: 3.60V
- Typical capacity: 5000mAh
- Minimum Capacity: 4900mAh
- Discharge cut-off voltage: 2.50V
- Charge voltage: 4.20V +/- 0.05V
- Standard charge current: 1300mA
- Maximum constant discharge current: 8A
- USB type-C charge socket.
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This is a 21700 cell with build-in USB-C charger, the cell is a protected high capacity cell.
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The two cells match just about perfect and can easily deliver the rated 8A.
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The USB charging uses a switching regulator to keep the heat down, I measured about 10°C temperature increase at the front of the cell during charge.
The USB-C input do not follow any protocols, except signalling it needs power.

Conclusion
It is a good battery and the USB charging means it can share charger with a mobile phone, this is very practical when traveling or when having only a few LiIon batteries. Only caveat is that the battery is considerable longer than a standard 21700 cell.
Notes and links
The batteries was supplied by Keeppower for review.
How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries
Graphical comparison to 18650 and other batteries
Table with all tested LiIon batteries