VapCell LG 20650 HG6 Batteries

High-current batteries in the rather unusual 20650 form factor caught my eye mainly because of their size, and partly because they can discharge at up to 30 A.
Tests, comparisons, the usual stuff.


I've had batteries in all sorts of sizes, including unusual ones like 10370, 26350 and 17670, and here's another "original": the 20650. Sanyo also makes batteries in this size, at least, under the name NCR20650A, but they're still quite uncommon.

A quick note on the price: when I wrote this review, they cost $16.99 for 2. The seller has since raised prices on many items considerably, so buying them makes a lot less sense now—unless you specifically need this size.

The packaging is the same thin cardboard boxes as before. Nothing fancy.


Key specs from the datasheet.


They're a deep blue, with a flat positive terminal that protrudes slightly beyond the casing. The date code indicates they were made in early March 2016, so they're pretty old. Interestingly, the datasheet dates back to early 2015, which means the HG6 cells themselves aren't all that outdated.


They're as long as the familiar 18650 cells, but their diameter is even a little over 20 mm. They weigh almost 60 g, noticeably more than the usual 45–48 g for an 18650.


The datasheet also lists the diameter as 20.5 mm, so that's fine. But according to the datasheet illustration, the positive terminal has four spokes, while mine have only three. I doubt anyone would bother counterfeiting cells like these; perhaps the illustration is schematic, or the design was changed later.


The preliminary test showed a capacity well below the claimed figure, especially for the first cell.


Two charging modes are supported: "standard," at 1.5 A (0.5C) with a 50 mA cutoff, and "fast," at 4 A with a 100 mA cutoff.

At a charging current of 1.5 A, the first cell took less than two hours to charge, which also points to a lower-than-claimed capacity. On the other hand, the CV phase wasn't very long, which is good.


At 4 A, charging took just under an hour, but the CV phase got considerably longer, which is definitely not a good thing.


According to the datasheet, the minimum discharge voltage is 2 V at currents up to 20 A. Since it doesn't specify a separate voltage for 30 A, I discharged the cells to 2 V at that current as well.
In total, I ran 9 tests at 0.2C, 0.5C, 1C, 2C, 10 A, 15 A, 20 A, 25 A and 30 A.

Unfortunately, the final capacity was 2746 mAh. The discharge curve also gets very steep toward the end, so there's no point in discharging down to 2 V. Even stopping at 2.5 V wouldn't make much difference, since the sharp drop starts at around 2.8 V.


The temperature performance was a pleasant surprise: even at 30 A, the temperature only reached 93.5 °C. Of course, calling a temperature just shy of 100 °C "only" sounds a bit odd, but I'm comparing how different batteries behave under roughly the same conditions. In this case, the lower capacity may also be a factor.

Here are the results at 20 A, 25 A and 30 A.


The second cell did better, but still fell short of the 2900 mAh minimum specified in the datasheet.


The temperature was about the same as for the first cell.


After discharging at 30 A and letting the cell cool down, its remaining capacity at 0.2C was 64 mAh, which is a very good result.


Comparison of how closely the test results match at 1C, 10 A, 20 A and 30 A.
The first cell is shown in blue. The curves look similar, but it's clear that it still lags behind the second cell.


The cells' impedance when they arrived, after "conditioning," and at the end. Around 9 mΩ is quite good, and partly explains their decent performance at high currents.


I spent a long time deciding what to compare these cells with, and Samsung 25S and Vapcell S30 seemed like the most useful choices. Both competitors are rated for a maximum current of 30 A, but are a little smaller. The S30 is rated not only for 30 A, but also for a capacity of 3000 mAh.

In short:
Blue — the cells reviewed here
Green — Samsung INR18650-25S
Red — Vapcell S30.

It may look surprising, but the S30 beat both of them in all three comparisons—at 1C, 20 A and 30 A—not just in capacity (mAh), but also in energy delivered (Wh). At 30 A, the results are almost identical. But the S30 is an 18650, not a 20650, and it’s anyone’s guess which one will last longer.



Conclusions.
In my opinion, these batteries would be pretty good, especially given their high current output. But they spent a long time in storage, which clearly didn’t do them any favors. I’d guess that because they’re already 5 years old, they couldn’t deliver the rated 2900–3000 mAh. The most I got was 2746–2812 mAh.

Would I recommend them? It’s not a clear-cut answer. If they’re new and the price is right, why not? But in the condition shown in this review, and at this price, definitely not—especially if you’re planning to use them in a battery pack. Besides, you can already find alternatives at this price, such as the VTC5D, which would even cost less.

That’s all for today. I hope this information was useful. Maybe someone knows of some interesting battery models I haven’t tested yet.