Keeppower 18650 3200mAh (Black) 2014
- Min Capacity: 3100mAh
- Typical Capacity: 3200mAh
- Normal Voltage: 3.7V
- Quality Lithium Ion rechargeable cell made in Korea
- Maximum capacity and reliability
- Size: L:69.00mm*D:18.50mm
- Cell made in Korea
- High Discharge Rate (Max 2C)
- Protection Circuit (Against overcharge, over discharge, over current and short-circuit.)
- 4.2 volts max voltage and 3.6-3.7 volts nominal voltage
- Over 500 times of charge and discharge cycle life.
This is the highest capacity cell with 4.35 volt at the current time, but due to the protection the mAh is to low.
The discharge curves does not looke very nice, but that is not due to any problem with the cell, it is because the protection has intefered with the charging.
It can also be seen that the protection trips after some time at 7A.
Here it is obvious that one cell stops charging, before the other and probably neither of them is fully charged (The voltage drop when the charge current stops looks to large).
Test with 4.3 volt charging
Reducing the charge voltage slightly gets around the problem with the proction.
The difference between 4.3 and 4.35 volt charging is minimal. This time the curves look fine.
Both cells is fully charged here.
Test with 4.2 volt charging
Using a normal 4.2 volt LiIon charger does cost capacity, about 250mAh compared to 4.3 volt.
Being based on LG cells, it is good batteries, but with the slightly low protection voltage they do not give the full benefit of the higher voltage.
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