# Test/Review of Keeppower IMR26650 5200mAh (Black) 2014



## HKJ (Jul 12, 2014)

[SIZE=+3]Keeppower IMR26650 5200mAh (Black) 2014[/SIZE]







Official specifications:

Min Capacity: 5100mAh 
Typical Capacity: 5200mAh 
Type: Li-Mn 
Normal Voltage: 3.7V 
Quality Lithium Ion rechargeable cell 
Maximum Capacity and Reliability 
Ultra Discharge Current: 30A 
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 capacity unprotected 26650, that is supposed to deliver 30A. It does not do that.




























There is a fairly good tracking between the cell, but they do not deliver 30A, they are more in the 10A to 15A range.

































[SIZE=+3]Conclusion[/SIZE]

The cells works fine as unprotected high capacity cell, but they are not really super high current cells.



[SIZE=+3]Notes and links[/SIZE]

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 batteries


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## THE_dAY (Jul 12, 2014)

Thanks HKJ! You are really cranking out these reviews one after another non stop!

It's surprising to me that Keepower's IMR 4200mAh has better performance than their IMR 5200mAh.


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## HKJ (Jul 12, 2014)

THE_dAY said:


> Thanks HKJ! You are really cranking out these reviews one after another non stop!



On average I get a bit above two tests each week, when I have batteries in queue.
And my queue is rather long at the moment.




THE_dAY said:


> It's surprising to me that Keepower's IMR 4200mAh has better performance than their IMR 5200mAh.



Better performance depends on what you look at, the 5200mAh has more capacity and energy, but the 4200mAh keeps a higher voltage.


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## Gauss163 (Jul 12, 2014)

@HKJ Looks like you have a typo in the specs (20A vs. 30A). Is that supposed to be burst, or continuous? Probably burst, given the test results.


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## HKJ (Jul 13, 2014)

Gauss163 said:


> @HKJ Looks like you have a typo in the specs (20A vs. 30A). Is that supposed to be burst, or continuous? Probably burst, given the test results.



The specs are copied from Keeppowers website, but I can see they have changed the 20A to 30A now.


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## StorminMatt (Jul 13, 2014)

HKJ said:


> Better performance depends on what you look at, the 5200mAh has more capacity and energy, but the 4200mAh keeps a higher voltage.



Good point. Despite the fact that this is supposedly an 'IMR' cell, it is really more of a higher capacity version of the King Kong. In fact, voltages are VERY comparable at the same current levels.


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## Overclocker (Jul 17, 2014)

hi henrik!

just a question. is this IMR26650-5200mah the same cell as the ICR26650-5200mah, BUT without the protection circuit?

i just looked at your comparator and the curves look almost identical except for the voltage drop caused by the protection circuit


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## HKJ (Jul 17, 2014)

Overclocker said:


> just a question. is this IMR26650-5200mah the same cell as the ICR26650-5200mah, BUT without the protection circuit?
> 
> i just looked at your comparator and the curves look very similar except for the voltage drop caused by the protection circuit



My guess is yes.


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## candle lamp (Jul 17, 2014)

Thank you for your excellent review. HKJ! :thumbsup:

I have a question. At 0.2A discharge current, the relating voltage is about 4.2V. But at 15A current, the voltage is around 3.5V.
Are those voltage initial voltage? And why is this happening? This may be some kind of stupid question. :thinking:


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## HKJ (Jul 17, 2014)

candle lamp said:


> I have a question. At 0.2A discharge current, the relating voltage is about 4.2V. But at 15A current, the voltage is around 3.5V.
> Are those voltage initial voltage? And why is this happening? This may be some kind of stupid question. :thinking:



What is initial voltage? Is it loaded or unloaded.

With a 15A draw I am placing a 0.24 ohm resistor (More or less) across the battery terminals. This makes a voltage divider with the internal resistance.
The math looks like this: 4.2/(0.24+0.07)*0.24 -> 3.25 volt

Because I am using a constant current load not a resistor, the correct math is: 4.2-0.07*15 -> 3.15 volt

The 0.07 ohm internal resistance has a large tolerance, it looks like my value is too high for a full cell.


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## candle lamp (Jul 17, 2014)

Thanks again. HKJ!
It's right answer to the wrong question.


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## SubLGT (Oct 28, 2014)

Overclocker said:


> hi henrik!
> 
> just a question. is this IMR26650-5200mah the same cell as the ICR26650-5200mah, BUT without the protection circuit?
> 
> i just looked at your comparator and the curves look almost identical except for the voltage drop caused by the protection circuit



I am puzzled that HKJ answered your question with a "yes". How can they be the identical cell if one has IMR chemistry and the other has ICR chemistry?


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## HKJ (Oct 29, 2014)

SubLGT said:


> I am puzzled that HKJ answered your question with a "yes". How can they be the identical cell if one has IMR chemistry and the other has ICR chemistry?



The correct usage for IMR is, of course, for a manganese based LiIon battery, but today it is often used for any high current battery.


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## Polargirl (Oct 29, 2014)

I wish the ICR version would fit in an Olight R40 Seeker


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## StandardBattery (Oct 29, 2014)

I'm surprised KeepPower is so far off with this battery spec and naming. They have a good reputation i would hate to see them lose that. I hope their dealers will strongly voice their disappointment. Thanks for the test, I've been waiting for this one. I expexcted better from this company not only is the use of IMR naming low class, the battery does not even meet comparable specs or posted spec. Still an interesting cell for low to moderate drain, it sure shows the value of independent tests. Do they have a published data sheet for this cell?


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## SubLGT (Oct 29, 2014)

HKJ said:


> The correct usage for IMR is, of course, for a manganese based LiIon battery, but today it is often used for any high current battery.



So IMR has become a marketing descriptor, instead of a technical descriptor. That is disappointing. What cell is likely to be underneath the KeepPower wrapper? A Panasonic?


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## HKJ (Oct 29, 2014)

SubLGT said:


> So IMR has become a marketing descriptor, instead of a technical descriptor.



Only for battery resellers, not for battery manufacturers.



SubLGT said:


> That is disappointing.



Yes, but not really that surprising.




SubLGT said:


> What cell is likely to be underneath the KeepPower wrapper? A Panasonic?



No, Panasonic does not make 26650. It is probably from a Chinese battery manufacturer.


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## SubLGT (Oct 29, 2014)

HKJ said:


> ……………...No, Panasonic does not make 26650. ………………………….



I did not know that. Is the Panasonic CGR26650B a fake, or genuine?


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## HKJ (Oct 29, 2014)

SubLGT said:


> I did not know that. Is the Panasonic CGR26650B a fake, or genuine?



I do not know that, but I have not seen any data on 26650 from Panasonic.


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## SubLGT (Oct 29, 2014)

I just checked for a 26650 battery on Panasonic's global battery website, and found no 26650 batteries. So the CGR26650B is probably a fake.


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## SubLGT (Oct 29, 2014)

StandardBattery said:


> ………...Still an interesting cell for low to moderate drain, it sure shows the value of independent tests. Do they have a published data sheet for this cell?



Well, I went ahead and ordered one of these KP batteries, for a moderate drain application, in a LumaPower Strive flashlight. 

The only "data sheet" I have seen is what is written on KeepPower's website:

1. Typical Capacity: 5200mAh (0.2C Discharge)
2. Minimum Capacity: 5100mAh (0.2C Discharge)
3. Nominal Voltage: 3.7V
4. Rated Charge: CC/CV,5200mA, 4.20V
5. Rated Charge Time: 2hours
6. Maximum Charge: 6A
7. Full Charged Voltage: 4.20V±0.05V, 50mA end-off current
8. Discharge End-off Voltage: 2.50 V
9. Max. Plus Discharge Current: 30.0A
10. Max. Constant Discharge Current: 20.0A
11. Initial Impedance: Max. 25mΩ
12. Weight: Approx. 92.0±1.0g
13. Dimension(D*H): Max.(D)26.20mm*(H)67.50mm
14. Operating temperature
 Charging: 0℃~45℃
 Discharging: -20℃~60℃
15. Storage temperature
 1 year：-20～25°C
 3 months：-30～45°C
16. Life: Over 2000 times charge & discharge cycle life


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## StandardBattery (Oct 29, 2014)

Polargirl said:


> I wish the ICR version would fit in an Olight R40 Seeker


The ICR version will work, but you'll press in the top of the battery a bit the first time you tighten the tail cap with it. *Now i can't say i'd recommend anyone else do it*, but I didnt have a problem with it but the R40 is just a tester for me and i would have only been mildly upset if i had broken the internal pcb in the process. As it turned out i'm happy to be able to test it with the 5200mAh cell.


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## SubLGT (Nov 2, 2014)

I wonder if KeepPower is using a LiNiMnCoO2 cell (NMC) in this battery and the IMR 4200mAh, instead of a LiMnO2 (LMO, IMR) ?


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## StandardBattery (Nov 2, 2014)

SubLGT said:


> I wonder if KeepPower is using a LiNiMnCoO2 cell (NMC) in this battery and the IMR 4200mAh, instead of a LiMnO2 (LMO, IMR) ?



I think HKJ's test of the KeepPower IMR 4200 mAh cell indicates it's probably a true IMR cell, and certainly a different chemistry from the IMR 5200mAh and ICR 5200mAh cells which appear to be identical to each other.


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## StorminMatt (Nov 2, 2014)

StandardBattery said:


> I think HKJ's test of the KeepPower IMR 4200 mAh cell indicates it's probably a true IMR cell, and certainly a different chemistry from the IMR 5200mAh and ICR 5200mAh cells which appear to be identical to each other.



I'm guessing the Keeppower IMR 5200mAH cell is a 'hybrid IMR' rather than a true IMR (much like the Panasonic NCR18650BD/PD/PF). These cells have somewhat higher (but not greatly higher) current capabilities than ICR, but with similar capacities.


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## SubLGT (Nov 3, 2014)

KeepPower claims a cycle life of 2000 for the IMR 5200mAh and IMR 4200mAh. Isn't that wildly optimistic?


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## StorminMatt (Nov 3, 2014)

SubLGT said:


> KeepPower claims a cycle life of 2000 for the IMR 5200mAh and IMR 4200mAh. Isn't that wildly optimistic?



Yes. LiFePO4 is the only lithium chemistry that can claim that kind of cycle life.


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## jessehere (Feb 25, 2017)

I just bought a set of these they're like $29 on Amazon for a pair kind of pricey


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