Test/Review of Keeppower IMR26650 4200mAh (Black) 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

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?

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.

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.

Click to expand...

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

THE_dAY said:

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

Click to expand...

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.

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?

Click to expand...

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.

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.

Click to expand...

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.

Click to expand...

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

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

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?

Overclocker said:

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?

Click to expand...

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.

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.

Click to expand...

MMU-X3 draws 5.0A

Overclocker said:

MMU-X3 draws 5.0A

Click to expand...

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.

Overclocker said:

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

Click to expand...

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.

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.

Click to expand...

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.

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.

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

Click to expand...

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?

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?

Click to expand...

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

HKJ said:

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

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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?

On a regulated LED light, no, not likely.

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

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?

Click to expand...

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.

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?