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



## HKJ (Jul 8, 2014)

[size=+3]Keeppower IMR26650 4200mAh (Black) 2014[/size]







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.








[size=+3]Conclusion[/size]

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.



[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 LiIon batteries


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## THE_dAY (Jul 8, 2014)

Great testing as always, thank you.

Why did the cell heat up enough to have melted shrink wrap, as I assume it was under normal testing just like you do to all other IMR cells?


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## Teobaldo (Jul 8, 2014)

Thanks for the review, HKJ, very complete as ever. I haven’t flashlights that use these batteries, however, when I buy some I will consider this model.


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## THE_dAY (Jul 8, 2014)

Teobaldo said:


> Thanks for the review, HKJ, very complete as ever. I haven’t flashlights that use these batteries, however, when I buy some I will consider this model.



There is also the Keeppower 5200mAh IMR 26650 which should be even better.


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## StorminMatt (Jul 8, 2014)

THE_dAY said:


> There is also the Keeppower 5200mAh IMR 26650 which should be even better.



It probably won't be better than this one at high current. But if you are just looking to run something like a simple XM-L2 light at 3A, it's quite a good battery. In a Foursevens Maelstrom MMU-X, you get over two hours of runtime on high - not bad for a hiking light.


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## HKJ (Jul 8, 2014)

THE_dAY said:


> Why did the cell heat up enough to have melted shrink wrap, as I assume it was under normal testing just like you do to all other IMR cells?




Yes, it was during normal testing. High current drain will always heat the batteries, but this time a bit more than expected.
According to the datasheet the Sony VTC5 can have a 55C temperature raise at 20A load.


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## THE_dAY (Jul 9, 2014)

StorminMatt said:


> It probably won't be better than this one at high current. But if you are just looking to run something like a simple XM-L2 light at 3A, it's quite a good battery. In a Foursevens Maelstrom MMU-X, you get over two hours of runtime on high - not bad for a hiking light.


Maybe you are thinking of the ICR 5200mAh from Keeppower recently reviewed by HKJ here:
http://www.candlepowerforums.com/vb...eview-of-Keeppower-26650-5200mAh-(Black)-2014

There is also the IMR 5200 mAh version from Keeppower not tested yet by HKJ but it is rated up to 20A. 


HKJ said:


> Yes, it was during normal testing. High current drain will always heat the batteries, but this time a bit more than expected.
> According to the datasheet the Sony VTC5 can have a 55C temperature raise at 20A load.


Ouch, I didn't realize they can get that hot under use, appreciate the data.


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## candle lamp (Jul 9, 2014)

Excellent review. HKJ! Thanks a lot. :thumbsup:


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## Overclocker (Jul 9, 2014)

thanks for the review henrik!

if you were to choose between:

a) KP ICR26650 5200mah
b) KP IMR26650 5200mah
c) KP IMR26650 4200mah

for a Maelstrom MMU-X3, which one would be the best for this flashlight?


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## HKJ (Jul 9, 2014)

Overclocker said:


> if you were to choose between:
> 
> a) KP ICR26650 5200mah
> b) KP IMR26650 5200mah
> ...



Depends on how much current it uses. If possible I would use the protected 5200mAh battery, next up is probably the unprotected 5200mAh. The last option would be the 4200mAh.


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## Overclocker (Jul 9, 2014)

HKJ said:


> Depends on how much current it uses. If possible I would use the protected 5200mAh battery, next up is probably the unprotected 5200mAh. The last option would be the 4200mAh.




MMU-X3 draws 5.0A


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## HKJ (Jul 9, 2014)

Overclocker said:


> MMU-X3 draws 5.0A



With 5A draw it might be necessary to use the 4200mAh, that depends on the driver in the light.

Try comparing them here: http://lygte-info.dk/review/batteries2012/Common26650comparator.php
The 4200mAh has about 0.2V advantage for a lot of the runtime.

I expect the unprotected 5200mAh cell will be somewhere in between.


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## StorminMatt (Jul 9, 2014)

Overclocker said:


> for a Maelstrom MMU-X3, which one would be the best for this flashlight?



I have both the MMU-X and MMU-X3. And I use the 5200mAH IMR 26650. Whether you use the IMR or ICR all comes down to what you like. I prefer unprotected cells for a number of reasons (including the fact that these lights already have low voltage protection). But if you prefer protected cells, the ICR is the only way to go.

As for current draw, keep in mind that, unless you are in cold conditions, the MMU-X3 only draws 5A for a short time. After a few minutes, it thermally steps down to closer to 2A.


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## THE_dAY (Jul 12, 2014)

StorminMatt said:


> It probably won't be better than this one at high current. But if you are just looking to run something like a simple XM-L2 light at 3A, it's quite a good battery. In a Foursevens Maelstrom MMU-X, you get over two hours of runtime on high - not bad for a hiking light.


I saw HKJ's new review and you were right, the Keeppower IMR4200 is better at high currents than their IMR5200. 
Even as low as 2A the IMR4200 cell holds higher voltage up to 3.5V.


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## SubLGT (Oct 31, 2014)

HKJ said:


> With 5A draw it might be necessary to use the 4200mAh, that depends on the driver in the light.
> 
> Try comparing them here: http://lygte-info.dk/review/batteries2012/Common26650comparator.php
> The 4200mAh has about 0.2V advantage for a lot of the runtime.
> ...



When I compare the IMR 4200mAh cell to the IMR 5200mAh cell with a 5A load, I see a maximum difference of about 0.15 volts between the two curves on the graph. The 4200mAh cell has less voltage sag. Does a 0.15V difference have a significant effect on the light output of a flashlight?


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## HKJ (Oct 31, 2014)

SubLGT said:


> When I compare the IMR 4200mAh cell to the IMR 5200mAh cell with a 5A load, I see a maximum difference of about 0.15 volts between the two curves on the graph. The 4200mAh cell has less voltage sag. Does a 0.15V difference have a significant effect on the light output of a flashlight?



If it is significant or not can always be discussed, but on single cell lights it will often affect light output.


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## SubLGT (Oct 31, 2014)

HKJ said:


> If it is significant or not can always be discussed……………………..



To be more specific, will a 0.15V difference have an effect on the light output that I can see with my own two eyes?


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## LEDAdd1ct (Oct 31, 2014)

On a regulated LED light, no, not likely.

On an incandescent...maybe, possibly, but certainly not very much.


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## HKJ (Nov 1, 2014)

SubLGT said:


> To be more specific, will a 0.15V difference have an effect on the light output that I can see with my own two eyes?



Depends. It will probably affect light output, also on regulated lights, but seeing a difference in light output is usual very difficult.
I.e. if you swap between two batteries I doubt it will be visible (Because it takes time to swap batteries), but if you have two lights and can swap between them very fast it is probably visible. 

This means that in practical usage it will not be visible.


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## SubLGT (Nov 1, 2014)

HKJ, after using your comparator tool, I am impressed with the KeepPower IMR 4200mAhBattery. When I look at the performance curves at 3A and 7A, _none_ of the other batteries in the 3000-5200mAh range are superior (in voltage sag) to the KP IMR 4200. The KeepPower has less voltage sag than the King Kongs, the Efests, the Xtar, the Enerpower, etc. But, as you say, that superiority in resistance to voltage sag may not actually be visible in routine flashlight use.

Apparently, KeepPower is being secretive about the identity of the manufacturer of their 5200 and 4200 mAh cells. Not even Illumination Supply has been able to get that information.

Do you have more 26650 batteries waiting to be tested?


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## HKJ (Nov 1, 2014)

SubLGT said:


> Do you have more 26650 batteries waiting to be tested?



Yes, two: Efest purple and a UltraFire 7300mAh.


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## SubLGT (Nov 1, 2014)

I predict the UltraFire 7300 will have a true capacity of 4200mAh! :naughty:

I'm looking forward to the test of the Efest IMR purple 3500mAh.

I would also be interested in seeing a test of the Efest IMR green 4200mAh, and how it compares to the KeepPower IMR 4200. But of course I leave that decision up to you.


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## HKJ (Nov 1, 2014)

SubLGT said:


> I predict the UltraFire 7300 will have a true capacity of 4200mAh! :naughty:



You are way to optimistic.





SubLGT said:


> I would also be interested in seeing a test of the Efest IMR green 4200mAh, and how it compares to the KeepPower IMR 4200. But of course I leave that decision up to you.



It is also up to Efest, they can sent it to me, but they will probably not do that before I have published tests of the last batch they sent.


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## Mr. Tone (Nov 1, 2014)

HKJ said:


> You are way to optimistic



I will take a guess at 3000 ma


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## HKJ (Nov 2, 2014)

Mr. Tone said:


> I will take a guess at 3000 ma



We are talking about UltraFire, they are often a good bit below rated capacity (The guess is still to high).


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## Mr. Tone (Nov 2, 2014)

HKJ said:


> We are talking about UltraFire, they are often a good bit below rated capacity (The guess is still to high).



Maybe their way of rating is to have the actual capacity be 0.2C of the labeled capacity!


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## SubLGT (Nov 15, 2014)

On Keeppower's website, they show the maximum charge current as being 6A (1.4C). Are such high charge currents typical for IMR cells?

http://www.keeppower.com.cn/products_detail.php?id=486


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## HKJ (Nov 15, 2014)

SubLGT said:


> On Keeppower's website, they show the maximum charge current as being 6A (1.4C). Are such high charge currents typical for IMR cells?
> 
> http://www.keeppower.com.cn/products_detail.php?id=486



Yes. This being a fairly large cell it can only sustain 1.4C, some smaller IMR cells can handle 2C or more.


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## SubLGT (Nov 15, 2014)

If a person wanted to charge their IMR cells at the maximum rate (be it 4A or 6A or 8A) aren't they limited to using a RC hobby charger? I know the Xtar VP2 charger I own is limited to 1A. Are there non-hobby Li-ion chargers from XTar, Nitecore, or other manufacturers that can charge at higher than 2A?


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## Mr. Tone (Nov 15, 2014)

Xtar now has one with a 2 amp charge rate.


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## Tapis (Nov 16, 2014)

Sorry for the noob question, but what is the downside of charging a battery to 2A or 4A comparing to 1A?


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## HKJ (Nov 16, 2014)

Tapis said:


> Sorry for the noob question, but what is the downside of charging a battery to 2A or 4A comparing to 1A?



Higher current will usual reduce the lifetime of the battery and very high current may make the battery explode.
With battery packs designed for fast charging you will often see 3 terminals, the 3 terminal is a temperature sensor. This is used to reduce or stop the charge if the battery gets to warm.


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## StandardBattery (Nov 16, 2014)

Tapis said:


> Sorry for the noob question, but what is the downside of charging a battery to 2A or 4A comparing to 1A?


"... charging a battery *to* 2A or 4A ..."

Probably just a typo you made... but just in case; the batteries are charged to their capacity, but it's how fast they are charged that is being discussed in the last few messages (the charge rate).


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## Vorador77 (Jan 19, 2015)

Anyone knows the difference between the long and the short version of this cell ?


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## HKJ (Jan 19, 2015)

Vorador77 said:


> Anyone knows the difference between the long and the short version of this cell ?



Are you talking about the protected and unprotected version?


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## Vorador77 (Jan 19, 2015)

HKJ said:


> Are you talking about the protected and unprotected version?


Nkon sells 2 versions, one (all black) listed as "short" (67,2mm) and one (black-white label) listed as "Long" (68,5mm). Both are unprotected


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## HKJ (Jan 19, 2015)

Vorador77 said:


> Nkon sells 2 versions, one (all black) listed as "short" (67,2mm) and one (black-white label) listed as "Long" (68,5mm). Both are unprotected



Then it may be a button top.


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## cpe812 (Mar 12, 2015)

HKJ said:


> Yes. This being a fairly large cell it can only sustain 1.4C, some smaller IMR cells can handle 2C or more.



Great Review 
Question: What 26650 battery do you consider to preform the best overall or top five? Now that there are more coming out of recent.


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## SubLGT (Mar 12, 2015)

cpe812 said:


> ………..What 26650 battery do you consider to preform the best overall or top five? …………...



http://lygte-info.dk/review/batteries2012/Common26650comparator.php


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