Inside UGREEN's "Liquid-Cooled" Power Bank: A Teardown of the MagFlow Pro 10,000mAh
イチケン / ICHIKEN
The UGREEN MagFlow Pro 10,000mAh is a magnetic power bank whose selling point is an active liquid-cooling system: when it starts charging a device, liquid visibly begins circulating inside the unit. Ichiken normally tries to avoid reviewing power banks, but they made an exception for this one because of its unusual cooling mechanism. This is not a review of the product as a charger. It is a teardown focused on how the cooling works and whether the internal design matches the marketing.
The Cooling Claim
UGREEN describes the product as using active cooling that circulates liquid internally, plus copper foil and an aluminum shell. Ichiken notes that a REDMAGIC smartphone they previously disassembled used a similar mechanism. According to UGREEN, the result is a temperature about 10°C lower than competing products during wireless charging, with the unit staying around 36°C.
Features and Specifications
The power bank has a built-in charging cable that can also serve as a strap, plus one USB-C port. Both are labeled IN/OUT, so either can charge the power bank or charge other devices. Wired output reaches up to 45W, and maximum input is 30W. The multi-port power split was shown in an on-screen chart that Ichiken tells viewers to pause and read.
The back has a Qi2-compatible wireless charging pad rated at up to 25W. In Ichiken's test, it reliably drew 25W. With 25W going out, the battery was delivering about 29W, so roughly 4W was lost. Ichiken attributes this to the wireless coil stage being less efficient than wired charging. The wireless pad is output-only and cannot recharge the power bank. A side display shows remaining charge and charging status.
The active liquid cooling starts when the bank begins charging another device. UGREEN states that the cooling system itself draws only 0.02W. Ichiken remarks that the visible movement gives the product a slightly "cool" feel.
Why Two Cells in Series
The battery is two 5,000mAh cells connected in series, for 39.2Wh. Ichiken points out that more and more power banks now use two cells in series. Most USB devices charge over USB PD at around 9V, 15V, or 20V. If the battery voltage is low, the boost ratio increases, and so does the loss in the power bank's conversion circuit. Raising the pack voltage, even slightly, is a way to deliver as much of the stored energy as possible to the device being charged.
Thermal Testing: 41°C, Not 36°C
Ichiken measured temperatures during continuous 25W wireless output, using a Qi2 trigger device to keep wireless charging stable, at a room temperature of 25°C. The maximum surface temperature was about 41°C.
Ichiken attributes the gap from UGREEN's 36°C figure to different test conditions rather than a false claim. UGREEN tested with an iPhone 17, and Ichiken doubts that an iPhone would actually charge wirelessly at a constant 25W, so they expect a difference of a few degrees.
The heat was also unevenly distributed. The hottest spot was 41°C while the center was 35°C, a spread of about 6°C. Ichiken guesses that the hottest area might contain a conversion circuit that adapts the battery voltage for wireless charging.
On the coil side, the wireless charging coil ran very hot. Because the Qi2 trigger sends its power to an external electronic load, this heat came purely from the coil, and it corresponds to the coil's power loss.
Price and Value
Ichiken paid 18,980 yen, and the price has since dropped to 14,180 yen. Even with 25W Qi2, about 40Wh of capacity, and active cooling, they consider it expensive. They bought it only to take it apart and say they don't think it's good value. Its performance is above average, but its price is even further above average. For value for money, they suggest UGREEN's other Qi2-compatible power banks instead.
Disassembly: An Aluminum Frame
Ichiken started cutting the case with an ultrasonic cutter, but something felt wrong. The entire outer perimeter of the case turned out to be aluminum, so they switched to filing it apart.
The structure has three main parts:
- a resin base that holds the charging circuitry,
- an aluminum frame that wraps all the way around, and
- a lid on top.
Ichiken assumes aluminum was chosen over plastic because it conducts heat well. They also explain why a metal exterior is acceptable here but not on a wall charger. A power bank runs at a lower temperature, around 40°C, which a person can tolerate touching even on metal. It is not connected to mains power, and its highest voltage is around 20V. Ichiken thinks that is why aluminum is acceptable.
The attached USB cable runs inside to a flexible printed circuit soldered to an adapter board, which connects to the internal circuit board through a connector.
The Main Board and Heat Path
The core of the unit is a battery cell integrated with a printed circuit board, which is the power bank proper. The Qi transmitter coil sits on the back. The board holds the charge/discharge control, the power conversion circuits, and the Qi coil driver, so it generates a lot of heat, and it matches the hot area in the earlier thermal images.
The board has two layers with a silicone heat-dissipation sheet between them, apparently to spread heat evenly across the whole area. The Qi coil wiring runs along the outer casing, and that also matches a localized hot spot in the thermal footage. Ichiken comments that transmitting as much as 25W through a wireless coil really does require enough current to generate some heat.
An Unexplained Flexible Circuit
On one side there was a flexible circuit board whose purpose Ichiken could not identify. The plastic frame has a recess cut out specifically to hold it, so they believe it has some function, but they didn't figure out what. They ask viewers to leave a comment if they know.
How the Cooling Layers Stack Up
The active liquid-cooling module sits on top of the battery/board module, directly over the area that showed high temperatures in the thermal scan. The apparent intent is to transfer heat from that area into the liquid and carry it away along a long channel.
However, a sponge containing an air layer is sandwiched between the cooling module and the board module. Because air is a good insulator, Ichiken says, this design prevents the board's heat from being effectively removed by the liquid-cooling module.
The lid goes on top, with a fairly thick sheet of copper foil stuck to its underside. Ichiken's reading is that heat from the board still reaches the liquid-cooling module despite the sponge's air gap. The copper foil then spreads that heat over the area it covers and helps dissipate it through the exterior.
Comparing the Hardware With UGREEN's Illustrations
Ichiken also compared the actual internals with UGREEN's promotional images:
- Aluminum shell: The image made them expect a separate metal sheet inside the case, as some power banks have. There was no such sheet. Ichiken thinks "aluminum shell" refers to the aluminum outer frame.
- Liquid-cooling tank: It was exactly as they had imagined.
- Copper layer: It looked like a vapor chamber in the image, but it turned out to be copper foil.
Ichiken notes that the image is labeled as an illustration and that they haven't tested the thermal design, so they stop short of a firm verdict. Still, they feel that removing the liquid-cooling part and spreading heat over a larger area with copper foil, graphite sheets, and silicone gap fillers might transfer heat better. They acknowledge that it isn't that simple in reality. They also think marketing, meaning appeal through visual novelty and technical features, is part of why this cooling configuration was chosen.
The Liquid-Cooling Module Up Close
The pump is easier to see from the back, and everything else in the module is flow channel. With the system running, some channels carry fast-moving liquid and others slow-moving liquid. Right after the pump outlet the streams converge, with one fast-flowing channel continuing on and the flow then turning into a slower channel. From there the path continues through fast and slow sections, winds around, and returns to the pump.
Many heat-generating components sit around the pump, with the circuit board directly beneath it, so heat from there enters the liquid. The thermal images support this: the temperature is high just after the pump outlet and drops as the channel runs to the far left. Because this area got quite warm during charging and discharging, Ichiken wonders whether more heat is actually being carried away than they had expected.
A Piezoelectric Pump and a Two-Tone Liquid
Ichiken wasn't sure what type of pump is used and guessed it was probably piezoelectric. The pump has three terminals. Using one as a common reference, they probed the other two and found voltages reaching nearly 100V at peak. They take that operating voltage as a sign that it is probably a piezoelectric element.
The liquid itself shows white and green regions. Ichiken first thought the white parts were bubbles, but the white portion moves downward, so it doesn't appear to be air. They think the green part is liquid and the white part is a liquid that is even heavier.
Conclusion: Toward Active Cooling
Ichiken closes by saying that power bank cooling seems to be moving from traditional passive cooling toward active cooling. They point to Anker, which has already announced a power bank with forced-air cooling. Two questions remain open from the teardown: what the mystery flexible circuit does, and whether this liquid-cooling setup actually outperforms a simpler heat-spreading design.
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Hello. I got my hands on a cool portable charger today, so let's take a look at this teardown review. This is the UGREEN Magflow Pro 10,000 mAh magnetic portable charger. I usually try not to review portable chargers, but since this product features an interesting cooling mechanism, I decided to do a teardown review.
When charging begins in this way, something starts moving inside the power bank. When I plugged it in, something inside started moving like this. This product circulates liquid internally for active cooling. The REDMAGIC smartphone I took apart before was also equipped with a similar cooling mechanism.
In addition to active cooling, the product description mentions that they also use copper foil and an aluminum shell for cooling. Perhaps because of this cooling method, they claim that when using wireless charging, the temperature reaches around 36°C, about 10°C lower than other companies' products. Rather than a review of this product as a portable charger, this will be a teardown review focusing on the internal structure.
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Before taking it apart, I'll give a brief overview of its appearance and features. The design includes a single charging cable. As you can see, it can also be used as a strap. In addition, it has one USB-C port. Both are marked as IN/OUT and can be used to charge the power bank itself and to charge other devices. The USB cable provides up to 45W of power. The maximum input power is 30W. The wireless charging output is up to 25W. When using multiple ports, the charging power is shown in this figure. Please pause and check this.
There is a Qi2-compatible wireless charging port on the back of the device. It supports up to 25W. When I actually tried charging via Qi2, you can see that it is reliably drawing 25W of power. When the output is 25W, the battery output is about 29W, so it appears there is a power loss of about 4W. Since it charges via a wireless coil, the efficiency of that part isn't as high as with wired charging. By the way, the wireless part is for output only; charging the power bank itself from this port is not possible.
It also has a display on the side, which lets you check the remaining battery level and charging status. What I'm most curious about is this active liquid cooling. When you start charging another device, active liquid cooling begins operating. Because there's movement, it gives off a slightly chilly vibe. By the way, it states that the liquid cooling system itself consumes 0.02W. Apparently, it can operate with extremely low power consumption.
Regarding the battery, two 5,000 mAh battery cells are connected in series. It's 39.2Wh. These days, more and more portable chargers are using two batteries connected in series. That's because most USB devices support USB PD charging and usually charge at voltages around 9V, 15V, or 20V. If the battery voltage is low, the boost ratio increases, and the power loss generated by the conversion circuit inside the portable battery tends to get bigger. Efforts have been made to increase the energy available for charging as much as possible by connecting the batteries in series to increase the voltage even slightly.
We also measured the temperature during charging. This is the temperature when the device is operating continuously at 25W via wireless charging. To ensure stable wireless charging performance, this time I used a Qi2 trigger device. The room temperature is 25°C. Here are the experimental results. The maximum surface temperature is approximately 41°C. Although the test results shown by UGREEN indicate a temperature of 36°C, this is due to differences between UGREEN's test environment and Ichiken's experimental environment. The temperature measurements conducted by UGREEN use the iPhone 17. When charging an iPhone, I don't think it will be wirelessly charging at a constant 25W, so I think there will be a temperature difference of a few degrees.
If we take a look at the temperature distribution as well, it's pretty inconsistent. The highest temperature was 41°C, while the temperature in the center is 35°C, so there is a temperature variation of about 6°C. On the part that's getting the hottest, I'm guessing it might have some kind of conversion circuit inside for using the battery voltage for wireless charging.
Next, let's take a look at the side with the wireless charging coil. The coil section was getting very hot. Since the Qi2 trigger I used this time consumes power through an external electronic load, this heat comes purely from the power loss in the coil itself.
Before we break it down completely, let's take a look at the product price as well. At the time I purchased it, the price was 18,980 yen. It's even cheaper now—14,180 yen. It supports 25W Qi2 with a battery capacity of approximately 40Wh. Even with an active cooling mechanism, I think this price is high. I bought it to take it apart, but to be honest, I don't think it offers good value for the price. As for performance, it's above average, but the cost is even higher than that. I think buying another Qi2-compatible power bank offered by UGREEN would be a better choice in terms of value for the money. I've also compiled links to other products in the description, so if you're interested, check it out.
Let's take it apart. I'm going to take it apart using an ultrasonic cutter, but while I was cutting the exterior, something felt really off. Upon checking again, it turns out that the entire outer perimeter of the case is made of aluminum. So, instead of using an ultrasonic cutter, I'm disassembling it by filing it down.
Here is the power bank after it has been disassembled. This is an aluminum frame. It looks something like this and goes all the way around. The base of this item is made of resin. It contains the charger's circuitry, and the aluminum frame is shaped like this. The design is such that a lid is placed on top of that.
Since the outer frame was made of aluminum, it conducts heat well. I suppose that's why it's aluminum rather than plastic. Unlike USB chargers, the temperature is lower, at around 40°C. This is a temperature that a person can tolerate when touching the metal. Also, regarding voltage, power banks are not connected to a commercial power source. The voltage is around 20V at most, so I think that means it's okay to use aluminum.
The USB cable that was connected to the main unit is soldered to a flexible printed circuit adapter board inside. This connector is designed to connect to the internal circuit board. It's right here on the internal circuit board.
As for the internal circuitry, it works like this: battery cells integrated with a printed circuit board form the main unit of what is commonly known as a power bank. On the back, there is a Qi charging transmitter coil. This part of the printed circuit board contains various charging and discharging control circuits, power conversion circuits, and the Qi coil's drive circuit, so it generates quite a bit of heat. Even looking at the thermal imaging footage from earlier, this part was getting very hot.
The printed circuit board consists of two layers, and the design incorporates a silicone heat-dissipating sheet sandwiched between the layers. It seems the goal is to distribute the heat evenly throughout the entire area. The Qi coil wires run along the outer casing. In the thermal imaging footage shown earlier, this matches the area where there was localized heating. If you transmit as much as 25W using a wireless coil, it really does require a current strong enough to generate some heat, doesn't it?
There was a mysterious flexible circuit board on this side. It is unclear what role it plays. Since there is also a recess carved out in the plastic frame to hold the flexible circuit board, I do think it plays some kind of role, though I didn't understand it. If anyone knows the answer, I'd really appreciate it if you could leave a comment.
An active liquid-cooling module is mounted on top of this battery and printed circuit board module. The area that showed elevated temperatures on the thermal imaging scan is where this printed circuit board is located. Does that mean they were transferring the heat generated in that area to the liquid and cooling it along this long waterway? However, between this active liquid-cooling module and the battery and printed circuit board module, a sponge with an air layer was sandwiched in between. Since air is a good insulator, the design prevents heat generated in this printed circuit board section from being effectively dissipated by the active liquid-cooling module.
Finally, this lid goes on top. A fairly thick sheet of copper foil is affixed to the underside of the lid. Although there is an air gap created by the sponge, the heat from this printed circuit board section is transferred to the liquid-cooling module. The purpose of the copper foil is to distribute the heat widely across the area it covers and effectively dissipate heat through the exterior.
As for the differences between these images and the ones released by UGREEN, based on this image, I was thinking there might be a single sheet of metal inside the aluminum shell. In fact, there was no aluminum sheet included inside the power bank. However, since the outer frame was made of aluminum, I think that's what they called the aluminum shell. The liquid cooling tank is exactly as I imagined it. As for the copper foil, in the sample image it looks like a vapor chamber, but it turned out to be copper foil. It's kind of hard to put into words, but it does say "illustration."
Since I haven't tested the heat dissipation design, I won't go so far as to make a definite claim, but I feel like removing this liquid-cooled part to keep it simple and combining copper foil, graphite sheets, silicone gap fillers, and so on to dissipate heat over a larger surface area would improve heat transfer. But in reality, it's not quite that simple. Since there are also marketing considerations involved, such as appeal based on visual novelty and technical features, I think that's why they chose this cooling configuration.
Now, let's take a closer look at the active liquid cooling system. This part right here is the pump. It's easier to see from the back. Everything else is part of the waterway. Here's what it looks like when you actually run it. It seems there are flow channels where the liquid flows quickly and others where it flows slowly. There's a point where the streams converge right after they come out of the pump. Where the streams converge, there's a single fast-flowing channel that continues into a slow-moving channel. After that, the path continues straight ahead through fast-flowing or slow-flowing sections. Finally, it winds around here and flows into the pump.
As I mentioned briefly earlier, there are many components around the pump that get hot. The printed circuit board is located directly underneath it. This means that the heat generated there was transferred to the liquid. When you look at the thermographic images, the temperature is high immediately after it comes out of the pump. If you follow the waterway to the far left, the temperature had dropped. Even when charging or discharging the portable battery, this area had gotten quite warm, so I do wonder if more heat is escaping than I expected.
I'm not sure about the type of pump used in the liquid-cooling module, but it's probably a piezoelectric element. Since there were three terminals coming out of the pump, I am using one as the common point and measuring the remaining two terminals with probes. When I measure the voltage, it looks like this. The voltage is quite high, reaching nearly 100V at its peak. Judging by this operating voltage, it's probably a piezoelectric element.
Let's also take a look at the liquid inside. I thought this white part might be a bubble, but when you look at it this way, the white part is moving downward. So it doesn't seem to be a bubble. The parts that look green are also liquid. I think the white part is actually a liquid that's even heavier than that.
Today, I did a teardown review of a portable battery featuring an active liquid-cooling system. Regarding the cooling of these portable chargers, it seems like active cooling is about to become the next big thing after traditional passive cooling. Anker has also already announced a portable battery with forced-air cooling.
Speaking of chargers, the domestic charger project being led by CIO and Ichiken is also currently running a crowdfunding campaign. If you're interested, please check it out via the link in the description. Thank you for watching the video all the way to the end.
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