Ugreen PB107 Power Bank with a claimed capacity of 10000 mAh

Power banks are pretty rare subjects in my reviews. Somehow, I hardly ever use them in everyday life, but when I was offered the chance to review one, I decided not to turn it down.
As usual, this review covers the exterior, teardown, tests, and conclusions.


One reason I agreed to review this device was its high sales volume—more than 1,500 units—which indirectly suggests it’s fairly popular. Naturally, I was curious whether it really is an interesting model or whether it’s simply a case of the “bandwagon effect.”

The order arrived in a branded green bag, which stands out against the usual yellow, black, and gray packaging. Inside was a neat cardboard box wrapped in soft material. Overall, no complaints about the packaging—it’s excellent.


The package includes:
1. Power bank
2. USB-to-microUSB cable
3. Manual and warranty card
4. Hook-and-loop cable tie


The manual is in English, but it’s easy enough to figure out.
The cable is short, about 30 cm long. It also comes with a cable tie, presumably for bundling the cable, but I think they could have come up with something to attach the cable to the power bank itself.


The specifications in the manual were what interested me most, since those are exactly what I’m going to check in this review.



Dimensions: 138 × 75 × 15 mm
Input: 5 V, 2.1 A
Combined output: 5 V, 2.1 A (maximum)
USB 1 output: 5 V, 2.1 A
USB 2 output: 5 V, 1 A
Battery capacity: 10000 mAh (37 Wh)
Capacity at 5 V output: 6250 mAh (at an output current of 1 A)
Maximum input voltage: 5.25 V
Charging time: 5 hours (with a 5 V, 2.1 A power supply)


The power bank looks like a flat stone with all its edges rounded off, partly because of the color scheme and partly because of its shape. The plastic feels slightly soft and rough, like a soft-touch coating.


The dimensions specified by the manufacturer.


The dimensions match the specifications. The weight is a little higher, though: it’s listed as 228 g, but the actual weight is 234 g.


For a better sense of its size, here it is next to a couple of smartphones: the one on the left has a 5-inch screen, and the one on the right has a 6-inch screen.


All the ports are on one end of the case.
Input: microUSB
There are two outputs: one is marked 2.1 A, the other 1 A.

Almost all the stated specifications are printed on the other end.


Four charge indicator LEDs are located on top of the case.


The indicator is very simple. During discharge, there are five levels:
75–100%: all four LEDs are on
50–75%: three LEDs are on
25–50%: two LEDs are on
10–15%: one LED is on
0–10%: one LED flashes

Charging works a little differently:
0–25%: the first LED flashes
25–50%: the first LED is on, the second flashes
50–75%: the first and second LEDs are on, the third flashes
75–99%: three LEDs are on, the last one flashes
100%: all LEDs stay on.


There’s also an on/off button. The power bank can actually turn on when a load is connected, but in practice I found that it doesn’t always do so. It also switches off automatically after 30 seconds if the load current drops. I didn’t determine the exact cutoff threshold. It’s not very convenient, but it stays on at 100 mA.

To turn it on manually: press the button briefly
To turn it off manually: hold the button for more than 3 seconds.

The button matches the color of the case, so you might not notice it at first glance.


Now for some tests.
First, I fully discharged the power bank, then charged it through a USB tester. The charging current was about 2.13 A, and charging took 9.3 Ah and almost six hours.
Actually, I simply didn't notice when the power bank finished charging, because I found it fully charged 6 hours later. So it would be more accurate to say no more than 6 hours. I think it really took about 5, as stated in the description.
I was able to discharge 6.24 Ah; the description claimed 6.25 Ah, which is close enough. We can consider this test passed.


In its advertising, the manufacturer says how many times you can charge various devices, but I don't have those devices, so I can't verify this claim.


Based on my initial tests, it looks like the two USB outputs are connected in parallel, which is fairly typical for devices like this. The only difference is the voltage configuration on the USB port's data lines, which tells the connected device how much current it can draw.
The settings for the 1 A output are on the left, and those for the 2.1 A output are on the right.


But the actual current depends on the device itself. If the voltage configuration on the data lines is suitable, it can draw almost 2 A quite happily even from the 1 A port.
For example, on the left is another power bank charging, and on the right is a Lenovo smartphone charging. By the way, the tester shows that the smartphone requests 12 V using the QC protocol, but the power bank doesn't support this feature and supplies it with 5 V. The charging current was still 2 A, though.


To estimate the maximum output power, I connected both devices shown above at the same time.


The experiment produced three results:
1. Switching the loads had no effect on the total current. In the first photo, the smartphone is connected to the 2.1 A output; in the second, it's connected to the 1 A output. In fact, the only way to tell which device is connected to which output is by looking at its current draw.
2. The total current was 2.35 A in both cases.
3. But since nobody promised this much current, the voltage dropped to about 4.62 V, below the 4.75 V minimum.


For further testing, I had to take the device apart.


At first I thought it was glued together, as is often the case with cheap devices, but no: there are lots of clips around the perimeter, and they're very tight. The designer clearly didn't expect anyone to take it apart. But as I mentioned above, the plastic is soft, so although the clips bent out of shape a little, they didn't break.


The clips near the connectors (left) are arranged a little differently from those on the opposite end (right). Either way, they're designed so you can't release them properly—only brute force will do the job :)


Another thing I was worried about was the cover being stuck to the battery with double-sided tape, as is done in some smartphones. But here, too, it's been done properly: the battery surface is protected by something like a mixture of foam and rubber.


The battery itself is attached to the case with soft double-sided tape, and I couldn't remove it.


The power bank's circuit board is very small. You can see the controller and inductor.


Interestingly, the board in the advertising image looks very much like the one installed here, but the image is mirrored :)
The ad also claims that the device is protected against:
1. Overcharging
2. Overcurrent
3. Overdischarging
4. Short circuits
5. Output overvoltage
6. Power overload
7. Automatic protection recovery
8. Electromagnetic radiation
9. Overheating


The temperature sensor mentioned in the ad is also visible here, attached to the battery case.
The power bank's model number and the circuit board's design date are also marked here, along with the type of controller installed.


The IP5189 controller handles almost everything, as indicated by the marking on the board. It also manages charging, overheat and overload protection, and the indicators.

Here I'll digress briefly to discuss the charging function.
There are two main battery charging methods: linear and PWM. The charging method has a significant effect on how much capacity a USB tester reports as having been “put in.”
With linear charging, the reported “put-in” capacity is usually almost the same as the actual capacity.
With pulse charging, it depends heavily on the input voltage: the higher the voltage, the less the tester will report.

This is because with a linear charger, the current through the charger and the battery is the same. With a switching charger, it depends on the difference between the battery voltage and the input voltage; the higher the input voltage, the greater the difference. In other words, in the second case, the current through the battery is always higher than the current from the power supply, so the tester will underreport the capacity.

This power bank uses a switching charger: the controller simply works in one direction while charging and the other while discharging. This operating mode usually doesn’t allow so-called “pass-through charging,” but it looks like this controller can enable bypass mode, meaning that while charging, it routes power from the input directly to the output.
I tried connecting the power bank to a charger with a load attached. The current from the charger was added to the load current.
For example, the power bank charged at 0.65–0.7 A with no load, and at 1.65–1.7 A with a 1 A load. There is a catch, though: when the charger is disconnected, the output voltage also drops briefly, so this setup won’t work as an “uninterruptible power supply.” Also, the input current is limited to 2.16 A, so if the load draws more than that, the power bank won’t charge.


The battery terminals are welded to pads on the circuit board, so I had to bend them back a little to see what was underneath the board.
The underside of the board is covered with the same soft material, and the LEDs are separated from each other to prevent light bleed.


The assembly is very neat, and there’s an extra copper pour under the PWM controller to dissipate heat.


As I mentioned above, the manufacturer claims a whole bunch of different protection features. The battery protection is implemented separately from the rest and is built around the well-known DW01 controller and a pair of MOSFETs.
This circuit provides protection against overload, overcharging, and overdischarging.


Speaking of protection, the next test measured the maximum current the power bank can supply. The load was connected directly to the converter board, or more precisely, to the USB connector contacts.
It turned out that the power bank can supply up to 2.5 A at 4.8 V, with protection kicking in at 3 A. At first, the protection tries to restart several times, and you can hear faint clicks. If the load isn’t removed, though, the power bank shuts down after a while.
I also noticed a small quirk: up to 0.7 A, the output voltage is 5.07 V; above 0.7 A, it jumps up by 0.1 V. This is most likely an intentional feature to compensate for voltage drop in the cable. Since the change happens in steps, it’s handled by the PWM controller.

In any case, this test gets top marks for load current, output voltage stability, and protection. Plus, there’s a “bonus” feature: output voltage compensation at higher load currents.


Output ripple is 50 mV and doesn’t depend on the load current. Below are the waveforms at 0.5, 1.0, 1.5, 2.0, 2.1, and 2.5 A. Some output voltage jitter was observed only at 2.5 A, but since the rated maximum is 2.1 A, this parameter gets a pass too.


And, of course, another important test: measuring the battery’s actual capacity. As I mentioned above, the power bank has a switching charger, so the capacity can only be measured accurately by connecting directly to the battery. In general, this is the correct way to measure it. Also, although lithium batteries have only a small difference between the capacity “put in” and “taken out” in mAh, it’s more accurate to measure during discharge.


The test went as follows:
1. The power bank was fully discharged.
2. After discharging it, I connected a load and discharged the battery at 0.2C, which in this case is 2 A. The cutoff voltage was 2.8 V.
3. Then I fully charged the battery using the standard method, i.e. with the power bank itself.
4. After charging, I waited about half an hour, then started discharging at 0.2 C while measuring the capacity.

The battery delivered the rated 10 Ah without any problems, and its voltage was 3.1 V.


The discharge continued, with readings taken at 3.0, 2.9, and 2.8 V. The results were as follows:
The battery's total capacity is 10.16 Ah, or 36.78 Wh, which matches the rating.

After that, the battery was charged to the standard 4.2 V, with charging stopped when the current dropped to 200 mA (1/10 of the charging current).
Charging took 10.54 Ah, or 42.3 Wh, which surprised me a little. Lithium batteries usually show a 1–2% difference between charge and discharge in Ah (not Wh), but here the difference was 4%.
Further investigation showed that the power bank charges the battery to 4.17 V, not 4.2 V, which is another plus. The battery wears out a little less, but apparently its actual capacity is also slightly higher than the rated 10 Ah.


And the final test: the current the USB ports can deliver, including contact resistance. Here, too, everything looks good: up to 2.5 A, the power bank maintains a voltage of at least 4.8 V, but at 2.6 A the voltage drops below 4.6–4.7 V.



Video version of the review, plus a look at the details of power bank circuit design


So, what do we have? First, the advantages:
1. Excellent build quality and materials
2. The battery's actual capacity is higher than rated
3. It has all the necessary protection features
4. Output voltage compensation to offset voltage drop in the cable.
5. Actual output current up to 2.5 A, versus the rated 2.1 A
6. Automatic startup.
7. Charge indicator
8. Charging terminates at 4.17 V instead of 4.2 V to extend battery life
9. Pass-through charging.
10. Low ripple across the entire load range.

Unfortunately, it has a few drawbacks, too.
1. The case is effectively non-serviceable. That said, since the battery accounts for most of the device's cost, replacing the whole unit is easier than replacing the battery alone.
2. No QC support.
3. The output voltage briefly drops out when you disconnect it from the charger, so it can't be used as a UPS.

Unfortunately, the device doesn't support fast charging and has only one output voltage, 5 V, although many manufacturers are now trying to equip their devices with Quick Charge, which supports output voltages up to 12 V.

Otherwise, I'd give this power bank five stars. I really like that it not only looks neat and feels good in the hand, but also delivers the rated specs—and even exceeds them in some respects.
It also comes with a decent USB cable and a small gift, though I haven't figured out what to do with it yet :)
In short, if you don't need Quick Charge, I recommend it.

The store currently has a discount of 1 off 19, so the actual price will be around $20.5, but the 11.11 sale will most likely bring a much bigger discount.

That's all for now. As usual, questions and comments are welcome.