SANYO UR18650ZY

While the big, important reviews are in the works, I decided to put together a short review/report in the “Look what arrived” series.
So, today’s review is a test of SANYO UR18650ZY batteries. If you’re interested, come on in.

I ordered 52 of these batteries, as I mentioned in the relevant thread.

I placed the order as soon as I read the thread. It was for 52 batteries (13 lots), split into 3 packages: two were sent to me, and one to a friend’s address.
The holidays caused a bit of a delay in delivery—or, more precisely, in dispatch. Once I was given the three tracking numbers on January 12, everything proceeded as usual.
I received them on February 10, a month and a half after placing the order. All three packages were trackable and arrived at the same time.


And here’s a group photo.


And here are the beauties themselves.
They’re wrapped in red heat-shrink tubing. If you look very closely, you can make out the marking embossed on the tubing, though it isn’t visible in the photo :(
SANYO L
UR18650ZY T23A

Judging by the marking, they were made in June 2015.


But a marking was visible through the heat-shrink tubing.
D TDAZY5D
087977

D TKUZY5B
034912

The lower number was different each time; the upper marking came in only three variants, two of which are shown above.


Photos of the positive and negative terminals. The negative terminal also has a marking, partly repeating the one printed under the heat-shrink tubing, but it’s not very clear either.
I tried to find out online what this marking means, but unfortunately I haven’t found anything yet.


A little about the technical specifications.
I found a datasheet for these same batteries online, though it’s for Panasonic-made cells. As I understand it, they’re one and the same.
The datasheet is pretty sparse, so here are the specifications I found elsewhere.

1. Min. Capacity: 2500mAh (0.2CA discharge)
2. Typical Capacity: 2600mAh (0.2CA discharge)
3. Nominal Voltage: 3.7V
4. End Voltage: 2.75V
5. Charging Current (Std.): 1.75 A(0 ~ +40°C)
6. Charging Voltage: 4.20±0.03V
7. Charging Time (Std.): 3 hours
8. Discharging Current (Std.): 2.5A (-20~ +60°C)
9. Discharging Current (Max.): 5.0A (0~ +40°C)
10. Internal Resistance: less than 100Mω(AC Impedance 1kHz)
11. Weight: less than 48g
12. Surroundings temperature range for shipped battery
less than 1month: -20 ~ +60°C
less than 3months: -20 ~ +45°C
less than 1year: -20 ~ +20°C
Note: Percentage of recoverable capacity 80%

I’ll be testing them based on these figures and the datasheet.
The datasheet specifies a maximum battery length of 65mm and a maximum diameter of 18.6mm.
Weight: up to 48g.


Now, on to the testing.
I didn’t test all 36 cells; I picked 12 at random.
The specifications include the following:
Typical Capacity: 2600mAh (0.2CA discharge)
0.2C is about 500mA, which is exactly the discharge current my four-channel charger uses.
The cutoff is 2.8 V rather than 2.75 V, but I don’t think that matters here, since the measurement accuracy of this device is worse than the difference between those values.


Each test lasted about 8 hours: 2 hours charging (the batteries arrived at 50% charge), 5.5 hours discharging, and half an hour charging (it's not a good idea to leave batteries discharged).
The capacity spread was 2773–2848; given the measurement accuracy isn't particularly high, that's quite good.


For the next test, though, I had to dig into the datasheet and check the test conditions for these particular batteries.
In other words, I needed to know the charge and discharge conditions under which the stated capacity was measured.
I found two graphs in the datasheet. I decided to use the graph on the left, although it doesn't really matter; it gives a higher capacity than the one on the right (compare the capacity at 20°C and a current of 1C).


Accordingly, I set the battery tester to the following parameters.
Charge current: 1.75 A, up to 4.2 V
Charging stops when the charge current drops to 0.1 A (the datasheet specifies 50 mA, but the tester won't let me set a current below 100 mA).
Discharge at 2.5 A, stopping at the specified 2.75 V
Then a full charge at 1.75 A.


Only 8 batteries were included in this test, since each test takes about 5 hours, and testing a large number of batteries would take a long time and serve no purpose.

Here are the results.
Battery number, capacity in mAh, capacity in mWh
1 2550 9082
2 2527 9010
3 2548 9101
4 2564 9163
5 2551 9082
6 2551 9072
7 2508 8952
8 2532 9031

Only battery number 7 performed slightly worse. I could test it again, but I don't see the point: all eight batteries meet the datasheet specifications and have a capacity above 2500 mAh.

For anyone interested in the graphs, I took screenshots and grouped them in sets of four. Click to view a larger image.

Besides the battery capacity, the description also includes the following line:
Internal Resistance: less than 100Mω(AC Impedance 1kHz)

So I also checked the internal resistance, which is within the specified limits as well.
The only thing is, the description specifies the resistance at 1 kHz, and I didn't think to check what test mode was used.


Besides the standard discharge current, batteries usually have a maximum (continuous) discharge current rating.
I actually came across the page with these batteries' specifications while looking for that rating. For these batteries, it's listed as:
Discharging Current (Max.): 5.0A (0~ +40°C)

Five amps it is, then. I fully charged the battery, set the discharge current to 5 A and the cutoff voltage to 2.75 V, and started the test.
Battery number 8 was tested, and it delivered a capacity of 2569 mAh.
The capacity was actually a little higher than with a 1C discharge current. I think that's because the battery had already gone through several tests at 500 mA and 2.5 A, and had also been topped up before this test.
But the energy was lower: 8724 mWh versus 9031 mWh at 2.5 A. That's the price you pay for discharging at the maximum current.


Since this kind of test usually heats the battery up considerably and pushes it to its limit, I measured the battery temperature during the test.
At the end of the test, the battery temperature was 57.5°C, with an ambient temperature of 26.2°C. That's a temperature rise of about 31°C, which is a good result.


And that's about it.
In summary: the batteries are good, with no issues. As for the price, decide for yourself whether they're worth it.

As always, I'm looking forward to your questions, additions, and comments.