Vapcell Boston Power Swing 5300 Batteries in an Unusual Form Factor

I got these batteries for review for two reasons: a request from readers and plain curiosity. Although I’d read a review of them before, this is the first time I’ve held them in my hands.


There aren’t many reviews of these batteries online, mainly because they’re relatively uncommon. At least, I haven’t seen batteries like these from any other manufacturer.

They arrived in their own cardboard boxes, simply and neatly packaged.


The design is unusual: the batteries look like two 18650 cells joined together, but there are a few differences.
Unlike conventional cells, the small contact is negative, while the positive terminal is brought out to the casing. I’ve seen something similar on batteries from Lithium Werks, so keep this in mind.
They were made by the Taiwanese division; there’s also a division in China. There’s a sort of matrix code, but it’s the same on both batteries. Most likely it encodes the batch number rather than a unique number for each cell.
I’ve come across several comments asking for help identifying the production date, but the datasheet doesn’t provide that information. I tried to figure it out by looking through a number of photos, and my guess is that the date is shown at the very bottom of the marking as five digits: the first two are the year, and the remaining three are the day of the year. So if that’s right, these batteries were made in mid-February 2017.



As I mentioned above, there’s a datasheet with all the main specifications and graphs. I’ll include screenshots from it below.

Capacity: 5300 mAh; discharge current: up to 13 A.


There’s another model in the same form factor called Sonata. The key differences are an impedance of 24 mΩ versus 15.5 mΩ for the Swing, and a rated service life of 1000 cycles versus 3000.


Dimensions and weight. As you can see, they really do look a lot like two 18650 cells joined together.


I put them in the charger for a conditioning cycle with a capacity measurement. Even at this stage, I can say that while you can charge them this way, it’s not very convenient.
At the discharge current, I measured capacities of 5133 and 5437 mAh—a rather large difference. The batteries were initially charged to about 40%.


The specified standard charging current is 0.7C (3.7 A), with fast charging at 2C (10.6 A). The datasheet graph is for standard charging, which should take about 2 hours 30 minutes.


Yes, technically everything matches the datasheet, but in my view these batteries are very slow to charge. The CV phase drags on, especially for the first one.


The second one did a little better: it took more charge in less time. Still, I don’t think that changes the overall picture. I suspect that charging at a current of " won’t speed things up much.


The manufacturer provides test results at load currents of 0.2, 0.5, 1, 1.5, and 2C, where C = 5300 mAh.
There’s also a graph showing capacity versus temperature. It indicates that normal operation is possible down to 0°C. You can go as low as -20°C, but capacity will start to drop noticeably—though 4 Ah at -20°C is still pretty good.


In my tests, I checked them at currents of 0.2, 0.5, and 1C, as well as 10 and 13 A.
The results for the first one were so-so; it barely managed to exceed 5 Ah.


Battery temperature at currents of 5.3, 10, and 13 A.


The second one performed noticeably better, fully meeting the stated specifications.


The temperature was a little higher here. I think that was partly because the warm-up time was also longer, but the difference is insignificant, and 13 A really is close to the maximum for these cells.


The large variation in performance between the two batteries was a real disappointment. The preliminary test was fully borne out: the first one has noticeably worse characteristics.


But interestingly, the first battery’s impedance at 1 kHz was slightly lower, i.e. By this measure, it comes out ahead.
Results as received, after "conditioning," and after the tests.


Naturally, questions are to be expected, and the first is: where are these batteries used?
They were originally designed for electric vehicles, where they are assembled into modules, for example, 8 cells at a time, making 3.65 V, 42 Ah battery packs.


There are also versions positioned as competitors to Tesla batteries. This information is from 2014, so things may have changed since then, but these modules looked pretty decent. It’s worth noting that Boston-Power is the actual manufacturer of the cells and the battery packs made from them.


These cells are also often used in batteries for light electric vehicles, such as e-bikes.
Their key selling point is a claimed service life of up to 3,000 cycles before capacity drops to 80% of its original value. But for some reason, the manufacturer only provides a capacity fade graph for 600 cycles.


By comparison, Sonata cells are rated for the more familiar 1,000 cycles, and their graph covers the same number of cycles.


These batteries can also be found in power banks.


At first, I thought these batteries weren’t used all that often, but it turns out you can buy not only holders for assembling battery packs, but also insulating cardboard cut to the right shape.


I can already hear the second question: are there actually two 18650 cells inside?
No, the manufacturer decided to do things its own way here.


Whether that’s a good idea is hard to say, but in any case, there aren’t two 18650 cells inside. I haven’t opened mine yet, especially since a search online turned up a full teardown of identical cells.

Yes, the design is debatable, but it’s definitely original.


And now for the verdict.
These batteries are a mixed bag, mainly because, in my opinion, their capacity/size/discharge current ratio isn’t very good. For example, a 2P pack made from Samsung 35E 18650 cells can easily deliver 6.5 Ah at the same current. With the well-known VTC6 cells, you get 6 Ah, but with a discharge current of up to 30–40 A, clearly more than the 13 A of the cells reviewed here.
Yes, the manufacturer claims a decent cycle life, but if you use the cells mentioned above under lighter loads, I think their service life will be comparable. The one thing that really sets these cells apart is their claimed operating temperature range down to -40 degrees.

It’s also worth mentioning consistency between cells. The batteries in this review show a fairly wide spread in their specs, which is exactly why I test at least two units: testing one is just a test, while two gives you at least a little bit of data. As for the capacity difference, I suspect they may have been stored improperly, affecting one battery more than the other.

And then there’s the price: $11 each is a lot. In fact, to circle back to the beginning, that’s the price of two decent 18650 cells.

In short: attractive, unusual, original, and they work—but that’s about it. If you find them cheaper (by a factor of 1.5–2), they’re worth buying. Otherwise, you’re better off with the "classic" cells or the "newcomers" in the 21700 size.


That’s all from me. I hope this was useful, or at least interesting :)