Basen 18650 2500 mAh 22 A batteries

This is the third review of Basen batteries, and today we're looking at a relatively unremarkable 2500 mAh model. Still, I hope the information will be useful.


As before, the batteries come in two little boxes, but this time they're yellow, hence the Y25 marking: Yellow 2500 mAh.

The price depends heavily on the quantity. The two-pack featured in this review costs $11.34, or about $5.60 per battery. A single battery costs $6.48, but there are also lots of 10 and 20, with free shipping.
The store has a 215 discount


Apart from the color and marking, the exterior is identical to the batteries in the previous review: the same slightly recessed positive terminal, and a barcode. The only difference is that this one is rated at 2500 mAh, with a continuous discharge current of 22 A.


Unfortunately, identifying the actual manufacturer has proved difficult so far. This battery has just one distinctive feature: hourglass-shaped notches on the safety vent. I checked the similar batteries I had on hand and found three. One was immediately ruled out because its positive terminal has a different shape. The other two (Samsung 25R and Murata VTC5A) don't have these notches on the vent, although their positive terminals look similar.


I'll leave the identification attempt for later and move on to the tests. As usual, first up are the dimensions and weight.


The batteries arrived with about 35% charge. A “conditioning” discharge at 500 mA down to 2.8 V yielded 2750 mAh, which is pretty good.


As with the B30 (VTC6), I charged the batteries at 1C (2.5 A), stopping when the current dropped to 100 mA. A full charge in this mode takes 1 hour 20 minutes, which is normal for mid-range batteries.


I tested discharge currents of 0.2, 0.5, 1, 2, 4, 6 and 8C, where C = 2.5 A.
I have to point out not only the good results, but also the characteristic increase in capacity (in mAh) at higher discharge currents. I've seen this with VTC4 batteries and a few others, although capacity usually drops proportionally as the current increases.


At 10, 15 and 20 A, the temperature was almost identical to that of the 25R batteries and noticeably higher than with the VTC5A.


The second sample produced almost identical results. In some tests (0.2C, 15 and 20 A), the capacity in mAh matched exactly. I even double-checked to make sure I hadn't made a mistake when putting the graphs together.



Resistance when received, after “conditioning,” and after the tests. Note that resistance increased by about 0.5 mΩ by the end.


But I was still curious about what batteries I had in front of me. As another attempt at identification, I put the test results for the three batteries in this review, the VTC5A and the 25R on one graph, at 0.2C, 10 and 20 A. Unfortunately, the differences are quite substantial.
The VTC5A simply delivered less capacity, while the 25R graph had a completely different voltage drop slope. Capacity was similar at 0.2C and 10 A, though, and at 20 A the Y25 under review outperformed both competitors.


After digging around on the Danish guy's website, I found some very similar Sanyo UR18650NSX batteries. At least they have a similar capacity (2500/2600 mAh), discharge current (22 A), and the same relationship between delivered capacity and load current/temperature, although they run cooler.


What's more, judging by the photos, they even have the distinctive notches on the safety vent. But then I remembered that Sanyo batteries have another equally distinctive feature: their negative terminal is marked, which isn't the case with the ones under review.
I did see photos of what looked like Vapcell batteries, supposedly based on Sanyo cells, with no markings on the bottom. But who knows, maybe those were photoshopped :)


Based on all of the above, I can conclude that:
1. These are clearly not VTC5s.
2. They're almost certainly not 25Rs either.
3. In terms of performance, the Y25 is no worse than the Samsung 25R, or at least comparable.
4. The two batteries tested produced very similar results, which is encouraging and usually indicates a decent manufacturing process.

Now for the bad news.
1. I still haven't figured out who the actual manufacturer is. Maybe someone will recognize something familiar about them.
2. So it's hard to say anything about their longevity.

In short: not bad at all, especially considering the relatively low price. I don't see any problem with using them not only in e-cigarettes, but also in power tools as an alternative to the VTC5 and 25R mentioned above.

I wasn't originally planning to publish a review today, but the store has some kind of winter sale and it ends tomorrow, so I decided to go ahead in case it comes in handy for someone.