Vapcell K29 18650 2900mAh 20A batteries

It's been quite a while since I last reviewed any batteries, so Vapcell sent me a few new test subjects. Today, we're looking at the first pair.
I can't really say anything bad or good about them. They're perfectly decent batteries, but nothing particularly special.

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I actually received two pairs of batteries, one 18650 pair and one 21700 pair, as well as a compact charger. It's still being tested, though, so I'll tell you about it later.

The title lists a price of $14.08 per pair. As I understand it, that includes the case, but they also have another listing at $17.99 per pair, also with a case. Shipping is free in both cases, so I don't understand the point of offering this option.



Specifications from the Vapcell website.
Model: K29
Size: 18.3*65.2mm
Typical Capacity: 2900mAh (0.2C discharge)
Min capacity: 2800mAh (0.2C discharge)
Nominal voltage: 3.60V
Max Continuous Discharge Current: 20A
Max Discharge Current: 35A
End-of-charge voltage: 4.20V
End-of-discharge Voltage: 2.5V
Weight: 48g ( Appr)
Internal resistance: 14mΩ ( Appr) （AC 1kHz）
Standard Charge: 1500mA ,CCCV 100mA cut-off
Quick Charge Current: 4000mA


You can already see that these are very ordinary mid-range batteries. Even their capacity is a little lower than that of other well-known types, such as the 30Q and VTC6.

The exterior is typical Vapcell: neat, with brief specifications and an authenticity code for verification.


Dimensions, weight—pretty much all as usual.


The batteries arrived at about 50% charge. In the initial “conditioning” cycle, they delivered slightly less capacity than specified.


As usual, the first test is a look at the charging profile, which can sometimes tell you what a battery is like right from the start.

Two charging modes are specified: standard at 1.5A and fast at 4A. Interestingly, the charging current isn't tied to capacity. It seems to me the manufacturer is just pulling these figures out of thin air.

At 1.5A, charging took about two hours, which is perfectly normal.


The batteries also handled charging at 4A reasonably well, though I wouldn't recommend charging them this way—or at least not very often.


Vapcell's website has its own capacity test graph, showing the battery tested at currents of 2, 10, 15, 10, and 25A.


I usually test at more appropriate rates—or, more precisely, rates based on capacity. Some are therefore expressed using the letter C, where C is the rated capacity, and the discharge rates are directly tied to it: 0.2C, 0.5C, 1C, and so on.

In this case, I tested the batteries at 0.2, 0.5, 1, 2C and 10, 15, 25A.

Well, that's pretty good. They fell a little short of the 2900mAh listed in the specifications, but that's not critical since the minimum rated capacity is 2800mAh, and the measured result is clearly closer to 2900.


In my view, the case temperature at discharge currents of 10, 15, and 20A is also perfectly reasonable—at least comparable to that of their closest competitors.


The second test battery performed about the same.


The temperature wasn't much different either.


Naturally, I also ran a comparison test on the two cells. Most “no-name” cells fail it. But the consistency here is simply excellent, which suggests these are probably from a reputable manufacturer.


The manufacturer describes these batteries as “similar to the HG2” and also suggests some typical applications.


The manufacturer also has a comparison chart on its website, comparing the K29 with the HG2 at a discharge current of 20 A.
Credit where it’s due: Vapcell’s engineers didn’t try to make the K29 look better. If anything, the message is that their batteries may not be quite as good, but the difference is small, and they can certainly replace the HG2.


But I’m a simple guy, so I’ll compare the K29 with cells from other manufacturers—namely, the HG2, VTC6, and 30Q. The comparison is at 1C and 20 A.

Well, Vapcell’s comparison results were pretty much confirmed. The K29 has a slight edge over the HG2 at the beginning and in the middle of the discharge, but gives out a little earlier because of its lower capacity.
The K29 also falls behind the popular VTC6 and the less common 30Q, though I wouldn’t say the difference is large.


Battery impedance after delivery, after “conditioning,” and at the end of the tests. The results are also good and fully in line with the specifications.


While preparing this review, I found an interesting image on Vapcell’s website claiming that the batteries comply with the UN38.3 standard.
In short, this certification is issued for products (including batteries) that can withstand the harsh conditions they may encounter during transport, won’t catch fire in the event of a short circuit, and so on.

But after looking around Vapcell’s website, I couldn’t find the actual certificate—the proper document showing who issued it, to whom, which products it covers, and how long it’s valid.


That’s about it. Now for a few conclusions.
I’ll keep them brief today: these are perfectly decent batteries, and in my opinion they’re clearly from a reputable manufacturer. I just haven’t figured out which company supplied the original cells.
I was very impressed by how consistent their characteristics were—practically identical, which is rare. The batteries also performed well across the entire range of their specified continuous discharge currents.

It’s hard for me to say much about the price, especially with the constant price fluctuations for name-brand cells, unfortunately.

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