Test/Review of Keeppower 26650 4000mAh (Black) 2014

Batteries and Chargers Rechargeable Batteries
1

Keeppower 26650 4000mAh (Black) 2014



Official specifications:

  • Product Name: Keeppower Protected 26650 3.7V 4000mAh
  • Supplier: Keeppower Technology Co., Limited
  • Cell: China 26650 4000mAh
  • Capacity: Min. 3920mAh; Normal: 4000mAhDischarge:0.2CmA
  • Normal Voltage: 3.70V
  • Stanard Charge voltage: 4.20V
  • Standard Charge current: 2000mA
  • Charge Time(Std.): 3 hours
  • Standard Discharge Cut-off Voltage: 2.750V
  • Standard Discharge current: 800mA
  • Standard Discharge cut off current: 30mA
  • PCB Protection trip current: Above 10A
  • Storage Temperature:-20°C~+60°C Less than 1 month, -20°C~+45°C Less than 3 months
  • WeightMax 95g
  • Size(L)71.10mm*(D)26.50mm




The battery has good performance, but the over current protection does not work as expected.










The battery does easily live up to its rated 4000mAh and the two batteries has good tracking up to 7A.











The protection does not trip, I asked Keeppower about it and they told me the protection was at around 20A. This is way to high for this battery.
The over discharge and over charge protection is still supposed to work correctly.





Conclusion

This battery has good performance up to 7A, but the missing over current protection does reduce the safety some.



Notes and links

The battery 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

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Thanks for the review!

3

Thanks HKJ! This confirms what I've seen - the "2014" is a disappointment compared to their previous version - higher resistance, poorer performance across the board, even a worse higher trip point.

Did you notice they seem to be using cheaper, thinner metal for the cap on the + end?

Overall, it's a drop in quality for this cell, and for me, makes me wonder what they are doing across their product line.

4

Performance is about the same, as can be seen in my comparator.

The old version had slightly lower over current trip point, but it was also too high. Comparing the "Protection test", the new version handles high current better.

Review 2012 version

No, I did not notice that, but then I did not compare them. Looking at them both now, it looks like you are correct, it is thinner on the new version. This is probably part of making the battery shorter.

5

Ohh - I see the internal resistance was 0.08 on the old, 0.10 on the new and I looked at a couple of specific points on the 5A curves and saw a difference - this was before you added the new one to the comparator. I see now though, one of the old cells performed better than the other, and the other poorer performing cell match's the new ones -- hhhmmm.