LiitoKala 21700 4000mAh Lii-40A (Yellow)
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Official specifications:
- Model: Lii-40A
- Size: 21700
- Chemistry: IMR
- Nominal Capacity: 4000mAh
- Nominal Voltage: 3.6V
- Discharge: 40A Max Continuous
- Positive: Flat
- Rechargeable: Yes
- Dimensions: 21.2mm x 70.4mm
- Weight: 61.2g
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High current 21700 cells from LiitoKala and also with good capacity.
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The two cell matches discharge curves fairly well and capacity is nearly constant at any load.
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The cells get warm at high current.
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I do not know exactly what happend with the B cell, but my battery holder was melted, i.e. the strange curve is probably due to a damaged battery holder and not the cell.
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Conclusion
The cells has the rated capacity and capacity is fairly constant with load, but they do get rather hot at high current. This means they may handle high pulse current, but 20A or more in constant current is not a good idea.
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