Red Sony/Murata US18650VTC6, "Red Hot"

Today I’m reviewing the well-known Murata US18650VTC6 battery, but in a “new wrapper.”
A review, tests, and most importantly—a comparison with the regular “green” VTC6 cells.


Some time ago, I wrote that I’d ordered these batteries, but for some reason the regular ones arrived. I’d really wanted to get my hands on these specifically.
But then a friend ordered regular VTC6 cells and the opposite happened: red ones arrived. More precisely, since the green ones were out of stock, he was offered red ones instead, and he agreed.

These batteries cost more than the regular ones. For example, the “green” ones sell for €3.50 (€2.58 for 11 to 50 pcs), while the “red” ones are €5.25 each (€4.95 for 10 to 300 pcs).

But that’s not all: the store even has a listing where you can choose whichever color you like! They’re called Sony/Murata Konion US18650VTC6 and cost €5.00.


So far, these are the only batteries from Nkon that have arrived in some kind of individual packaging—in ordinary little bags.


Datasheet for the regular VTC6.


They look a little... unusual. They resemble the well-known Sanyo cells, but these are indeed Murata US18650VTC6.
The heat-shrink wrap is tight, but the original markings are faintly visible through it:
US18650VTC6 C6
Murata INR19/66 144

Below that is the standard safety warning, but there’s no matrix code or manufacturing date code. I’d guess these were originally an industrial series that was given a “consumer” look.

The positive terminal is slightly recessed relative to the front edge.


They’re about 0.1 mm larger than the “green” ones, and also weigh 0.1–0.15 g more.


The “conditioning” run yielded a capacity of 3200 mAh; the batteries initially had about 30% charge. The “green” ones gave the same results in this test.


Next, of course, comes the test under a proper load.


As I’ve mentioned several times, the charging algorithm for VTC-series batteries differs from the others. However, my tests showed that the difference from the familiar method, where charging stops when the current drops, is extremely small and can be ignored.


The manufacturer specifies a single charging mode at 1C, so these batteries were a little easier to test than those with a “standard” current of 0.5C. Charging takes less time, and a full test involves at least 7 complete cycles for each battery.


The store and the heat-shrink wrap claim these batteries are rated for 30 A, but the datasheet clearly specifies a continuous current of 20 A. Since I don’t have separate data for the “red” ones, I’ll test them using the same conditions specified for the “green” ones.


The results are typical for VTC6: at 0.2C, capacity is close to 3100 mAh; at 20 A, around 2900 mAh.

Below are seven graphs for currents of 0.2C (600 mA), 0.5C (1.5 A), 1C (3 A), 6, 10, 15, and 20 A.


In all the tests, though, the temperature was about 4–5 degrees higher than with the “green” ones, which I’ve tested several times before.
Results at the end of the tests at 10, 15, and 20 A.


The second battery shows roughly the same pattern as the first.



Internal resistance when received, after the “conditioning” cycle, and at the end of the tests.
It was about the same for the “green” ones, slightly higher—12.60 mΩ versus 12.55 here—but that difference can be attributed to measurement error. Interestingly, despite having the same internal resistance, the “red” ones get a little hotter.


And, of course, the main thing: a comparison with regular VTC6 cells.
At the “standard” current of 0.2C, they produced identical results, but under heavier loads they delivered slightly less—about 1% less capacity in mAh and 0.5–1% less in Wh. You could say the difference is within the measurement error.


So, what can I say? Basically, these are the same VTC6 cells, just with different heat-shrink wrap. At least, my tests didn’t reveal any significant difference. There may be some specific advantage, such as a longer service life or something else, but that's just speculation on my part. For now, my verdict is that these batteries are good, with no issues.

That's all. I hope you found this useful.