Vapcell K54 batteries rated at 5400 mAh and up to 15 A

Another battery from the 26650 size format, which is on its way out. Of course, this format will stick around for a while, since plenty of devices still need it. Even so, the 21700 size, with comparable capacity and performance, has been replacing it for some time now.
Inspection, testing, and a comparison with the Vapcell G53.


Batteries like these are often used in certain flashlights when you need a decent current and relatively long runtime. That’s why some readers asked me to test them. So I ordered a pair to see what they’re like and how they compare with their closest competitor from Vapcell, the G53.

They came in a simple plastic case, although reviews at the link in the title say they arrive in a branded case with a clasp.


Specifications:
Model: K54
Size: 26.4*65.1mm
Typical Capacity: 5400mAh (0.2C discharge)
Min capacity: 5250mAh (0.2C discharge)
Nominal voltage: 3.60V
Max Continuous Discharge Current: 15A
End-of-charge voltage: 4.20V
End-of-discharge Voltage: 2.5V
Weight: 98g ( Appr)
Internal resistance: 19mΩ ( Appr)（AC 1kHz）
Standard Charge: 2000mA,CCCV 100mA cut-off
Quick Charge Current: 4000mA

The heat-shrink wrap is red, and the positive terminal is flat, flush with the end of the cell.
The cells also have a few key specs printed on them: capacity, size, and maximum continuous discharge current.


The dimensions and weight are all as expected.


The batteries arrived at around 70–75% charge.
During the “normalization” cycle with the Vapcell S4 Plus charger, the batteries showed noticeably lower capacities than expected: 5123 and 5221mAh. The charger is generally quite accurate when measuring capacity, so I’m not sure why.


According to the specs, the batteries can be charged at 2A in standard mode and 4A in fast mode.
Charging at 2A took 3 hours.


At 4A, charging took 1 hour 50 minutes. The CV phase was noticeably prolonged, which is a little odd for a charge current that doesn’t even reach 1C.


Vapcell’s website has a graph of measurements they conducted themselves. According to the graph, the batteries have a capacity of 5469mAh at 2A.
There was also a capacity measurement in the reviews using a LiitoKala charger, with comparable results.


I tested them in six modes: 0.2C, 0.5C, 1C, 2C, 15A, and 20A. The 20A test was something of a “bonus,” since the batteries performed reasonably well at 15A.
In fact, the first battery didn’t even reach 5200mAh of capacity.


Temperatures at discharge currents of 10.8A, 15A, and 20A. Critical heating occurred only at the maximum current of 20A. Keep in mind that the rated maximum for these batteries is 15A.


The results at 0.2C were similar for the second cell, with capacity just over 5200mAh.


The temperature was slightly higher, but probably within the measurement error.


Comparison of the two cells at 0.2C, 2C, and 15A. For some reason, there was a noticeable difference at 2C; the results were very similar in the other modes.


The batteries’ impedance when they arrived, after “normalization,” and at the end of testing. Interestingly, the first cell showed a higher result in the final measurement, even though I always try to measure the batteries at the same temperature and in one session.


And, of course, a comparison with the G53 at 0.2C, 1C, 15A, and 20A.
The results surprised me a little. The G53 is rated for a higher discharge current and has slightly lower capacity, yet it performed noticeably better, beating the K54 in every test.



Conclusions.
Well, these batteries could have been very interesting if their capacity had matched what the listing claimed. For some reason, though, it was 200mAh lower, as shown both by my main electronic load and by the control cycle with the S4 Plus.
I liked that they handle currents up to 20A reasonably well and can genuinely run at 15A continuously. But they fell noticeably short of the G53 in both discharge performance and capacity.


That’s all for today. I hope you found this useful.