VapCell IFR10370 140mAh Batteries, Part Six: 10370 Size

Last time I covered 26350-size batteries. Today, I'm looking at cells in another uncommon size, 10370. They differ not only in size, but also because they're LiFePO4 batteries.


To be honest, I have no idea where this type of battery is used. I've read that it may be used in e-cigarettes. I was interested in them only because of their unusual size: they're essentially the smallest batteries Vapcell makes, and I simply wanted to test them.

As far as I can tell, the smallest lithium battery sizes are 07540 (e-cigarettes), 10180 and 10280 (flashlights), but I think those were "classic" lithium-ion cells, whereas these are LiFePO4. This type of battery is more stable and safer. In one of my reviews, I tried to kill one by discharging a 400mAh CR123-size cell at 7A (17C). And what happened? Nothing. I don't think it's possible to kill them.

So, let's get to the review.
The batteries are sold in lots of two, and there are three lot options. The price is slightly different for two of them; the third has paid shipping, but they still work out to about $5 each. They come in a plastic case, with each battery also packed in a small bag, probably to stop them rattling around inside, since the case is clearly too big for them.


Specifications from the Vapcell page - link.
Model: IFR10370 140mAh 1A
Size: 10.1*36.8mm
Nominal voltage: 3.20V
End-of-charge voltage: 3.65V
End-of-discharge voltage: 2.0V
Typical capacity: 140mAh (0.2C discharge)
Minimum capacity: 120mAh (0.2C discharge)
Weight: Max: 9g
Internal resistance: Max: 85mΩ （AC 1kHz）
Standard charge: 150mA, CCCV, 50mA cutoff
Quick charge current: 300mA
Max continuous discharge current: 1A


For a better sense of the size, here's a comparison photo with an AAA (10440) battery and an AA (14500)-size cell.


The positive terminal is flat and sticks out slightly beyond the casing. In my case, this made testing much easier, since the positive contacts on my holders are noticeably wider than the batteries' diameter.
There is no security code on the batteries; it's only on the box.


The dimensions match the specifications. They weigh 7g, against a stated maximum of 9g.


On AliExpress, I've only come across two types of similar batteries: Vapcell-branded ones with standard terminals, and ones with no heat-shrink tubing at all and solder tabs. The latter were listed as 130mAh (sometimes 140 or even 150).


Their charging and discharging parameters also differed, as did their intended use: for IQOS e-cigarettes



Since my bench chargers, which I use for the "training" cycle, don't support LiFePO4 batteries, I first fully discharged both batteries and then charged them according to the specifications.
At a charging current of 150mA (almost 1C), charging took less than an hour.


These batteries also support fast charging at 300mA. The cutoff is the same as for standard charging: when the current drops to 50mA. I wouldn't have set it any lower anyway, since that's the limit of my battery tester.


The manufacturer's page includes its own test, performed with an EBC-A40L tester. I don't think it's entirely reliable in this case, since devices like this have greater measurement error at very low currents.
Still, the test was run at 0.25, 0.5, 1 and 2A. As a reminder, the stated maximum continuous discharge current is 1A..


I tested the batteries at 0.5, 1 and 2C, and at 1, 1.5 and 2A. I had to skip the 0.2C test because that would be 28mA, while the electronic load's minimum current is 50mA.
The first sample delivered 133–135mAh at 140–280mA (1–2C). That's below the stated 140mAh, but still pretty good. At currents of 1–2 A, there is already a noticeable voltage drop.


The temperatures at discharge currents of 1, 1.5, and 2 A are nothing to worry about. At 1 A, the battery barely even gets warm.


The results for the second unit were slightly worse. At currents of 70–280 mA (0.5–2C), I did get the rated capacity, but only just, at 120 mAh.


Only at 2 A was the temperature about a couple of degrees higher than for the first unit; otherwise, everything was identical.


The internal resistance measurement confirmed the test results: the second unit has higher resistance. The left image shows the reading when it arrived, and the right one after eight cycles.


Well, what can I say? Formally, almost everything meets the specifications. At currents up to 280 mA, both units will deliver their minimum rated capacity of 120 mAh, but there is a noticeable variation between them. Also, despite the specified resistance of 85 mΩ, the second unit measured over 90.
You could say the batteries would deliver more if the charge cutoff were set to 20 mA instead of 50 mA, for example. But given the charge and discharge characteristics of LiFePO4 batteries, that would add 1–2 mAh at best.

In short, nothing unusual, apart from the size. They’re perfectly usable, but I’d also consider the versions without heat-shrink tubing that I mentioned in the review. They can sometimes be cheaper, although after digging through a ton of reviews, I couldn’t find a single test.