Test/Review of Keeppower IMR26650 4200mAh (Black) 2014

Keeppower IMR26650 4200mAh (Black) 2014

Official specifications:

  • KeepPower IMR 26650 3.6V/3.7V 4200mAh High Drain Li-ion Rechargeable Battery
  • Type: Li-Mn
  • Min Capacity: 4100mAh
  • Typical Capacity: 4200mAh
  • Normal Voltage: 3.7V
  • Quality Lithium Ion rechargeable cell
  • Maximum Capacity and Reliability
  • Ultra Discharge Current: 50A
  • 4.2 volts max voltage and 3.6-3.7 volts nominal voltage
  • Flat top: Yes
  • Dimension: (D)26.50mm*(H)67.000mm
  • Weight: Max. 95.0g

This is a high current 26650 battery, but as the test shows, the current rating is too optimistic.

One of the batteries got rather hot during my test and melted the shrink-wrap

Looking at these curves the cells does track nicely in capacity and can handle 20A, but 30A is too much.
The 50A may be meant as a pulse rating, but the specification does not say it, a pulse rating must also include a pulse time and preferable a repetition rate.

This test "only" goes to 15A and the battery handles it fine.


The battery has good high current performance for a 26650 battery, but not as good as the specifications promises.
The cell looks like good quality and as usual my rating will be acceptable, but do not run it at 50A.

It is also interesting to compare it to some of the best high current 18650, the large size has advantages at 20A.

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
Compare to 26650 and other larger LiIon batteries

I just did a product request for KP IMR3500, and now this already beats it in both capacity and with slightly less voltage sag under load.

This cell is a winner! Nice to see that 26650 cells now are catching up to their true potential.

Is it wrong to assume these are just a KK inside?

Or is it obvious from the readings it is not?

Thanks as always HKJ for another helpful review.

Great job HKJ. Considering the price compared to my EnerPower 26650’s, I think I may give some of these a try in my high power lights. From the sizing chart, they should fit perfectly in any of my 26650 lights just as well as the EnerPower’s or MNKE’s.

These have slightly lower capacity, but are considerably better at higher amps.

Cant be compared to KK.

You can compare cells here:


The available 26650 4200mAh seem to have a different wrapper?
Is this a new cell or just anew wrap?

I ordered one from GB in their latest coupon promotions:
Coupon: Keeppower
Comes to 12.74$ total with shipping.