Sanyo UR18650ZY 2600mAh (Red)
Official specifications:
- Rated capacity min.: 2450mAh
- Capacity: Min. 2500mAh, Typ. 2600mAh
- Nominal voltage: 3.7V
- Charging: CC-CV, Std. 1750mA, 4.20V, 3.0 hrs.
- Weight Max.: 48.0g
- Temperature: Charge: 0 to +45°C, Discharge -20 to +60°C, Storage: -20 to +50°C
This cell is some years old (Datasheet from 2012) and capacity and current is not very impressive by todays standard,
The discharge curve looks good, the two cells tracks nicely and capacity is fairly constant with load.
Conclusion
Being old style non-IMR 2600mAh cells they do have a fairly high voltage during discharge, in some applications this is an advantage compared to the newer 2900+mAh cells (This advantage is also shared with the 4.3(5) volt cells).
It is a very good cell.
Notes and links
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
Compare to 18650 and other batteries