Soshine LiFePO4 Batteries, or Three Plus One

Some time ago, I posted a review of Soshine 14500-format LiFePO4 batteries. Today I'm continuing that review: I'll tell you about three more batteries from this company, and run a few tests on the 14500 battery we already know.
There will be plenty of tests in this review, including a check of how well the batteries withstand extreme currents.



Last time, I talked about the advantages of LiFePO4 batteries, so I'll skip that part today. If you're interested, you can read about it in the previous installment; the link is just below.

Let's start with the test subjects.
1. Soshine 18650 LiFePO4 Protected Battery 3.2V 1800mAh - link, $13.71 for 4 pcs
2. Soshine IFR LiFePO4 Rechargeable Battery CR123 / 16340 3.2V 500mAh - link, $6.92 for 4 pcs
3. Soshine 2PCS IFR CR2 LiFePO4 Rechargeable Battery 300mAh 3.2V - link, $5.66 for 4 pcs.

As an extra
4. Soshine 14500 / AA LiFePO4 Battery Kit 700mAh - link, $9.08 for 4 batteries plus two dummy cells, full review.



I'll start with the largest batteries, which in this case are 18650s.
They come in a plastic case. I think anyone who's bought batteries has probably seen one of these. It's fairly brittle plastic, and its job here is to protect the batteries during shipping—which it usually does successfully.


The product description in the store is a bit odd.
Battery Type: IFR
Protected: No
Capacity (mAh): 1800mAh
Practical Capacity (mAh): 1500mAh
Voltage(V): 3.2V
Charge Current: 1A
Max. Charge Voltage: 3.6V
Max. Charge Current: 3A
Discharge Current: 1A
Max. Discharge Current: 5.4A
Charging Time.: About 2 hours
Discharge Time (h): 2hours

The description says the battery is protected, but then lists some more specs, including this particularly amusing line:
Type: LiFePO4
Nominal voltage: 3.2 V
Nominal capacity: 1800 mAh
Core cell weight: 40g
Size: D18.1 x H68.5mm
Continuous discharge: 5A / pulse: 3A
Typical fast charge current: 3.6A to 3.6V CC / CV
Fast charge time: 40 minutes
Cycle life at 10C discharge, 100 percent DOD: over 1000 cycles

Anyway, let's take a look at the batteries themselves. I'll use the specs printed on them as the basis for my tests.
18650, 3.6 V, protected. All clear here, though the production date is a bit strange...
The stated capacity is 1800 mAh, with 1500 mAh as the minimum. Standard charging current is 300 mA up to 3.6 V. Maximum charging current is 1.5 A.
Maximum continuous discharge current is 8 A down to 2 V.

The negative terminal is engraved with the manufacturer's name. The batteries weigh about 41.5–42 g, compared with the stated 40 g.

They're quite large, and too long to fit in standard holders.


I got around the length issue by using my auxiliary charger, which in this case served simply as a holder. Its power consumption in this mode is very low (up to 0.5 mA, if I remember correctly), so it can be ignored.


First run: charging at 600 mA, discharging at 0.2C, or 300 mA. I raised the charging current above the recommended value because otherwise the test would take far too long, and it wouldn't make a significant difference to the results.
As before, I measure capacity when discharging to 2.8, 2.5, and 2.0 V, and give the total at the end.

The graph clearly shows a sharp voltage drop once the charging current is switched off, and a steep curve at the end of charging.

The results:
Down to 2.8 V — 1466 mAh — 4.694 Wh
Down to 2.5 V — 24 mAh — 0.064 Wh
Down to 2.0 V — 9 mAh — 0.021 Wh
Total: 1499 mAh or 4.779 Wh

As with the 14500, most of the capacity is in the range down to 2.8 V. After that, the voltage drops very sharply, leaving just a tiny bit more capacity.
Charging took 1517 mAh or 5.125 Wh, giving an "efficiency" of 93.2%. That's pretty good, considering the battery has a protection circuit.




Let's move on to the second type of battery in this review. This one is a CR123 or 16340, whichever you prefer. This size is also available as 3 V primary batteries, and a lithium iron battery rated at 3.2–3.3 V makes an excellent replacement. The primary battery may have a higher capacity (1400 mAh claimed, 1200 mAh actual), but it also costs around 2–3 dollars offline, making it more expensive than the battery under review.
They come in boxes of two. And here I ran into a bit of a problem. The listing was supposed to include 4 batteries, and I needed 12 for a particular project, so I ordered 3 lots. But the mailer contained only three boxes. I later noticed a note on the package saying it had arrived damaged. The most curious thing was that the M.2 SSD I had also ordered was there, even though it's much smaller.
I contacted the manager, who confirmed that each lot contains 4 batteries, so I suspect the postal service, though they can't really be blamed: we ordered three boxes and received three boxes. All above board.



Since these batteries are smaller than the previous ones, their rated capacity is more modest, too.
Full specifications from the store page:
Battery: 16340
Battery Type: IFR
Rechargeable: Yes
Protected: No
Capacity (mAh): 500mAh
Voltage(V): 3.2V

I got the remaining specifications from the batteries themselves.
Charge current: 250 mA; fast charge: 500 mA up to 3.6 V
Discharge current: 500 mA; maximum: 1.5 A down to 2.0 V.

The diameter is just over 16 mm, and the length just under 34 mm. They all weigh about the same, with only negligible variation.


The first test used a charge current of 250 mA, with charging stopped at 100 mA (the charger won't go any lower).
Discharge current: 100 mA (0.2C).
The result was slightly below the claimed 500 mAh (1.6 Wh).
Down to 2.8 V - 370 mAh - 1.183 Wh
Down to 2.5 V - 7 mAh - 0.019 Wh
Down to 2.0 V - 3 mAh - 0.007 Wh
Total: 396 mAh or 1.209 Wh

Charging took 398 mAh or 1.345 Wh, giving an “efficiency” of about 90%.





And now for the last “test subjects,” this time in the CR2 size (also known as 5046LC, CR17355, CR15270). It turns out there's even a separate article about them in the wiki.
They came packed in one box, which was clearly not the original packaging, since they were rattling around inside.


Rated specifications:
Battery Type: IFR
Rechargeable: Yes
Protected: No
Capacity (mAh): 300mAh
Voltage(V): 3.2V

The batteries themselves are marked:
Charge current: 150 mA; fast charge: 300 mA, up to 3.6 V
Discharge current: 300 mA; maximum: 0.9 A, down to 2.0 V.

The batteries are almost exactly the size of 15270 cells. The one in the photo is slightly longer, but that's because of the electrical tape on the negative terminal.
The weight variation is also fairly small; the photo shows the lightest and heaviest ones.


I ran into a few difficulties here. I couldn't set the discharge cutoff current below 100 mA, even though it should have been 30 mA. The discharge current was also 100 mA instead of 60 mA.
The discharge current itself wasn't really a problem, but the cutoff current was trickier. Still, given the very steep discharge curve I showed earlier, I don't think the results would have been very different.

The first battery delivered:
Down to 2.8 V: 186 mAh — 0.587 Wh
Down to 2.5 V: 5 mAh — 0.013 Wh
Down to 2.0 V: 2 mAh — 0.005 Wh
Total: 193 mAh or 0.605 Wh

Charging took 207 mAh or 0.701 Wh, for an “efficiency” of about 86%.







As an extra, I ran a couple more tests, measuring the capacity of batteries that had been sitting for about two weeks.
I was also curious because these batteries had previously been tested at a high current, clearly higher than their rated current.



And finally, here are all the test participants together, in what you might call a group photo.


So, what can we conclude?
First, the bad news: all the batteries have less capacity than claimed. The 18650 is right at the minimum stated capacity; for the others, it's hard to say, since no minimum is specified. Their actual capacity is about 20% lower for the CR123 and 38% lower for the CR2.

Otherwise, everything seems fine. The 18650 has a protection circuit that actually works, though this makes it longer than the standard 65 mm. What impressed me most, though, was how the batteries handled high-current discharge. I discharged the CR123 at 7 A, despite its actual capacity being just 400 mAh—that's about 17C. I ran the little CR2 cells at 12C for an extended period, and the 14500 at 10C. No problems there, either.

The main advantage of these batteries is that they're LiFePO4, so they're well suited to replacing lithium batteries of the same form factor (CR123, CR2) and standard AA batteries (14500 + dummy cell). I can't say much about the 18650: compared with regular lithium-ion cells, its only advantages are a theoretically longer service life, a flatter discharge curve (which can sometimes be critical), and significantly greater safety. But there's a downside too: much lower capacity, by quite a margin.

That's all. I hope this information was useful. As always, I'll be glad to answer any questions or read your comments.