5 V, 6 A, 6-Port Charger with Charging Current Display

I got my hands on a rather interesting charger—or, more accurately, a power supply. But this name has become so firmly associated with this category of devices that it’s probably easier to call it a charger.
As always, the device has its pros and cons, which I’ll show you. I’ll also take it apart and give you some information on how to choose power supplies and chargers properly.

Most of my regular readers know that I like tinkering with various power supplies, so I try to make many of my reviews explain what’s needed and why. This review will be no exception: the power supply I’m looking at is just one example of how to—and how not to—build a proper power supply.
I already have an article where I explained the principles of choosing a power supply properly. In this review, I’ll repeat some of what I covered there, perhaps answer a few questions people have asked me in the comments and in private messages, and most likely lay the groundwork for some new questions :)

I’ll get to all of that around the middle of the review, but first, the usual introduction (after all, we’re looking at a power supply review) :)

Strictly speaking, this device is a power supply. But since it has USB-form-factor outputs and the corresponding control circuitry for charging phones and tablets, I’ll call it a charger.

The charger comes in a fairly sturdy cardboard box, which is a plus.


From the information on the packaging, we can see that the maximum combined output current is 6 A (at 5 V, that’s 30 W), with up to 3.5 A per port.
No, there’s no contradiction here, of course. It can supply 3.5 A per port, but that doesn’t mean 3.5 × 6. The total maximum current still must not exceed the stated 6 A; you’ll just have to draw less from the other ports :)


The packaging is clearly oversized for this charger, since it was rattling around quite a bit inside.
Still, it wasn’t damaged.
The package contains only the charger and a power cable. That’s it.


The power cable is good, but it doesn’t fit our outlets—that’s a downside. The packaging says the device is available with different cable versions, but unfortunately I got one that doesn’t fit our outlets.


I wouldn’t call the device compact. One downside is that it has no feet, which would have been quite handy. Overall, though, I like it: it’s neat, and I’d even say it feels solid and monolithic.


Leaving aside all the various labels, the charger has just six USB ports, a fairly large display, and a power input connector.


The display takes up a fairly large part of the front panel. That’s really its main selling point, since there are plenty of power supplies with similar output specs.
And the display isn’t just for show, as is sometimes the case with Chinese devices—it’s a fully functional part of the charger.

At the top, it shows the output voltage and the total output current (the one capped at 6 A).
Below that, arranged to match the USB ports, are the current readings for each output, along with a battery icon indicating the charging process.


For a quick test, I connected my tablet, which for some reason showed a charging current of only about 1 A.


All right, let’s connect a phone: 0.44 A, not much.


Then I remembered that I’d once tried charging it with a different cable, and the phone’s charging current was 1 A.
It’s a pretty well-worn cable, as the scorch mark shows. It was damaged by a very “good” power supply—or perhaps by a heavy load.


1. But nothing changed: still 0.44 A.
All right, maybe the phone is nearly charged. That’s not a big deal here.
2. I connect the tablet with the white cable it came with. Charging current: 2.14 A. Great.
3, 4. I run a small experiment with two tablets and two different cables. Both cables are the original ones for their respective tablets: black for the black one, white for the white one.
In one photo, the cables are connected to match their colors; in the other, they’re swapped. The difference is within the measurement error, so the charging current is limited by the device, not by the cables.


Let’s put together a little “test setup” using whatever we have at home.


Here I noticed that the battery icon next to the current reading for the port connected to the Bluetooth headset wasn’t blinking. The current draw is below the minimum threshold, so although it is charging, the display indicates that the device is charged.
There are three charging indicator states:
Off—the icon isn’t displayed.
Charging—the icon blinks.
Charging complete—the icon stays on.


Since I wanted to load the charger up to its maximum current, I replaced the headset with an old tablet. That gave me a setup of three tablets and three phones—a perfectly realistic scenario, say, for three people on vacation.


Interestingly, the old, barely functioning tablet draws 1.8 A. The total current drawn by the load was 6.29 A, which is more than the advertised 6 A, at least according to the device's display.


The whole setup charged for about 45–50 minutes, after which I measured the temperature of the charger's case. At its hottest point, it was 66 degrees.
I wouldn't call that low; to me, it's close to the limit for normal operation. The only reassuring thing is that the test was run at maximum load, and this kind of load rarely lasts long anyway. After an hour or two or three, the current drops.

Here's an overall shot. You can see that the oldest tablet, sitting on top, is getting hotter than the other connected devices.


There's not much else to test in this configuration, so let's open it up.
And here's a surprise: the case is glued shut. It was especially funny to see the warranty seal—not only was it still intact, it was completely pointless given how the device had to be opened :)


The back cover has ventilation holes. They don't do much, but at least they're there.


The device consists of two boards connected by connectors. The power board is essentially just a 5 V power supply, while the other board handles the display and current measurement.


We'll take a closer look at the display board later. For now, let's see what's inside the power supply.
It looks very neat.




Let's take a closer look and recall what I wrote in my article about choosing the right power supply.
1. A fuse is definitely useful. Sometimes it's covered with heat-shrink tubing, but more often it's marked F, F1, Fx, etc.
2. The input filter is present. The bridge rectifier is rated for 3 A and up to 1000 V, which is also good.
3. A fairly large input capacitor, secured to the high-voltage transistor with a dab of sealant. It's good that it's secured, but not so good that it's in a high-temperature area. On the other hand, everything in this power supply runs hot, so the designers didn't have many options.
4. A pair of output diode assemblies, each rated for 20 A and 100 V. I usually say that the diodes' current rating should be three times the output current. Here there's a sixfold margin: 2 × 20 A for a 6 A output is excellent. For voltage, 50–60 V would be enough; these are rated for 100 V, which is fine, although lower-voltage diodes usually also have a lower forward voltage drop.

I also usually say that the output capacitor capacity should be close to this rule of thumb: current in amps = capacitance in thousands of µF. So for this power supply, 6000 µF would be ideal; here it's a little less, at 5000 µF.
Of course, this depends on the switching frequency and the type of capacitors, but as a rough estimate with ordinary electrolytic capacitors, this rule works well enough.
The capacitors look rather questionable, but given their large capacity and the fact that the charger doesn't run at full power around the clock, they should be fine.


It all looks nice and proper, but in reality that's not quite the case.
At the input, it's standard practice to install not just a filter, but also a couple of other components: a thermistor and a varistor.
The thermistor limits the inrush current when the input capacitor charges (you've probably all seen the spark when plugging something into a wall outlet).
The varistor protects the power supply from voltage surges. If the voltage rises too far, the varistor usually fails short, blowing the fuse while leaving the device intact.

To help identify them, I gathered a few components for demonstration.
Top left: thermistors. They're easy to check; when cold, they have a very low resistance of 5–10 Ω.
Top right: varistors. You can identify them by their markings, which usually include a number such as 7, 10, etc. (the diameter in millimeters) and a voltage rating: 471 (470 V), 681 (680 V), 220 (22 V).
Bottom left: capacitors. They look a lot like varistors, but have different markings.
Bottom right: components you may also find in a power supply, but these are polymer fuses. They come in round (I couldn't find any at home) and rectangular shapes. They're very rare, and even rarer in high-voltage circuits. Like thermistors, they have very low resistance (less than 1 Ω).


There are different kinds of capacitors, too. Near the inductor, you'll most often find the ones shown at the bottom; they're marked X1 or X2. These are special interference-suppression capacitors connected in parallel with the power lines. The power supply we're looking at has one as well. We'll come back to the capacitors at the top a little later.


People sometimes get confused and think that the input filter in a power supply is there to stop interference from getting into the power supply.
That's not quite right. Most power supplies (and chargers) these days are switching types and generate a lot of interference. The filter is there to stop that interference from getting out of the power supply and into the mains. In other words, installing a filter is considered good practice, even though in most cases the user won't notice the difference.
The diagram at the top shows:
Green — thermistor
Blue — varistor
Red — capacitor.

It also shows the direction in which the interference is blocked.

Another option is the second filter circuit, which is even better: this version also blocks interference coming into the device.
There's also a third option, with a capacitor only on the right, but it's fairly rare and is most often found in non-switching power supplies.


We've gotten a bit sidetracked. Let's get back to the power supply.
You can see one of the safety slots between the high-voltage and low-voltage sections of the board. Power supply manufacturers often neglect this requirement, even though the slot is essential for safety.
Dust or dirt can form a conductive layer that may cause a breakdown and give the user an electric shock. A safety slot makes this much less likely, so it's quite important to have one.


Let's remove the heatsink and take a slightly «deeper» look inside the power supply.
I liked that the heatsink was secured to the transformer with a dab of silicone sealant. I should also mention that there's very little sealant in this power supply, which is good, and it's only used where needed rather than slathered on where it doesn't belong.


1. Input capacitor. Its capacitance should be at least equal to the power supply's wattage in watts, expressed in µF. This applies to 220–240 V mains voltage.
No issues here: the power supply is rated at 30 W and has a 68 µF capacitor, which means it should work just fine over a wider input voltage range.
2. Class Y1 interwinding noise-suppression capacitor. All good here.


The high-voltage transistor isn't visible in the photo. It's an 8N60C, rated for 7.5 A and 600 V.

I often get two questions in private messages.
1. How can you tell a proper capacitor from an improper one?
2. What voltage rating should the capacitor have?

Here's my answer.
1. The photo above shows the proper capacitors; the ones below are just high-voltage capacitors.
2. As far as I know, all capacitors marked Y1 and Y2 are safe to use, so there isn't a «wrong» voltage rating for them. Correct me if I'm wrong.

The difference between a «proper» capacitor and an «improper» one is that in the event of a fault, the proper one won't short out; it will fail open instead, keeping the user safe.


The transformer is another important component. To put it very simply, bigger is better. Transformer size depends not only on power, but also on the switching frequency. However, since common power supplies don't vary much in switching frequency (66–133 kHz), their transformer sizes should be roughly proportional to their power ratings.
This one uses a fairly large transformer, and although the output winding isn't made from litz wire, it's wound with a large number of thin wires.


You might ask what can go wrong with a small transformer. It's obvious enough that it may not deliver the required power.
But it will also run hotter during operation. The material used for the core has an unpleasant property: above a certain temperature, it loses its magnetic properties. In other words, the transformer effectively becomes two windings with almost no coupling between them.
If the transformer is small and overheats badly, this is what can happen. The photo shows a 5 V, 2 A charger; I don't think it needs any further comment.


The underside of the circuit board, with the safety slots visible.


1. The PWM controller is an OB2269, operating at 65 kHz. The relatively low switching frequency is partly why the transformer is quite large, although even at this frequency it was chosen with plenty of headroom.
2. As usual, the output voltage is regulated by the popular TL431. A classic solution.
The soldering is generally neat, and the components are secured to the board with glue. But the soldering on the output connectors and the jumper are not very reassuring.


I didn't draw the schematic this time, but here's a closer photo just in case someone needs to repair one of these power supplies.


Now we've reached the display board. Undo a couple of small self-tapping screws and simply remove the board.


It looks quite nice, at least from the front.


The underside looks pretty good too, but the flux residue left behind after soldering the connectors is a bit depressing. It says something about the manufacturer's standards—and not in a good way.
It probably doesn't affect performance much, if at all, in this case, but it doesn't look very tidy.


The board consists of two main sections:
1. The connector section, with the charging-current setting resistors (four small resistors next to each connector) and 0.1 Ω current-sense shunts. By the way, the description said the power supply could deliver up to 3.5 A at the output. That's not true; the actual maximum is 2.5 A. The resistors used here (the 0.1 Ω ones) are low-power types, and at 3.5 A they would dissipate more than 1 W, which could cause them to fail.
2. A microcontroller handles all the measurements. It's probably an STM, but the markings have been removed.


Above, I mentioned the resistors that set the charging current.
USB charging works by having the power supply present a particular resistor configuration on its terminals. The device detects that configuration and knows how much current it can draw. Since the device might be connected to a computer, whose USB port can supply no more than 0.5 A (0.9 A for USB 3.0), this safety measure is a good idea.
More details here.
This power supply uses the highest-current resistor configuration. Unfortunately, it doesn't support Quick Charge (fast charging at a higher voltage) and is one of the most basic models, although at this price it wouldn't hurt to include that feature.


Since I've taken this power supply apart, I can test it more thoroughly.
First, I'll check how well the power supply itself regulates the output voltage, without the display board.


I tested it from 0 to 7 A, and it performed perfectly: the power supply holds the voltage steady.
This test also shows that the output voltage display on the power supply itself is pointless: the voltage is so stable that the reading on the display doesn't change, even though the measurement is taking place. In my tests, it consistently showed 5.3 V.


I also checked it with a multimeter, just to be sure, and the readings were roughly in agreement.
A 0.013 V drop across the 0–7 A current range is a very good result.


For my second test, I decided to check the output ripple.


In my power supply reviews, I often draw attention to whether there’s an output inductor. That inductor is much more important than the one on the input.
This power supply has no output inductor; it’s been replaced with a rather sloppy jumper.
I removed the jumper and installed the first inductor I could find that was suitable for the current. Its inductance isn’t very high—just 1–2 µH—but I think the results will still be noticeable.

I checked the ripple from 0 to 7 A in 1 A increments, but left out some of the results to keep things brief. The results before the modification are on the left, and after on the right.
Here’s what we get:
1. — No load
2. — Current: 1 A, ripple: 60 mV; after the modification: 30 mV
3. — Current: 3 A, ripple: 70 mV; after the modification: 40 mV


1. Load current: 5 A, ripple: 110 mV; after the modification: 50 mV.
2. Load current: 7 A, ripple: 140 mV; after the modification: 100 mV.


As we’ve seen, the ripple dropped by almost half. That’s pretty good, so I went on to make another modification that’s often recommended online.
And while I’m at it, I’ll show you two more things.
1. Ceramic capacitors don’t have much effect on ripple
2. How something can sometimes go from “good” to “bad.”

First, I soldered in seven 0.15 µF ceramic capacitors: three before the inductor and four after it…


On the left are the waveforms after installing the capacitors; on the right, before the inductor. Note that the scale on the right is 200 mV per division, not 50 mV per division—the interference simply didn’t fit on the screen in the first shot.

1. — No load, 450 mV before the inductor
2. — Current: 1 A, ripple: 20 mV (was 30 mV); 300 mV before the inductor
3. — Current: 3 A, ripple: 35 mV (was 40 mV); 600 mV before the inductor


1. Load current: 5 A, ripple: 50 mV (was 50 mV); 650 mV before the inductor
2. Load current: 7 A, ripple: 50 mV (was 100 mV); 900 mV before the inductor
3. Then I remembered that my oscilloscope is actually a two-channel model. Years of using a single-channel oscilloscope, I guess.
Load currents are 3 A and 7 A, respectively.


The experiment showed that:
1. Capacitors have an effect, but the inductor has a much greater one.
2. Adding an inductor increases ripple before it, or, to put it simply, “fix one thing and break another.” Adding an inductor reduces output ripple, but it also shortens the life of the capacitors upstream of it. Keep this in mind: if things are working well as they are, it’s better not to modify them.
In power supplies, capacitors installed upstream of the inductor tend to fail (bulge or lose capacitance) much sooner than those downstream. This is precisely because of this effect. Before the modification, ripple in the same circuit was only 140 mV; afterward, it was 900 mV. So if you add an inductor, it’s best to install higher-quality input capacitors rated for a higher voltage as well.

And now for the last test.
I showed above that the display board has 0.1 Ω resistors, and the processor uses the voltage drop across them to determine the output current.
But these resistors also have a parasitic effect: they cause the output voltage to drop under load.
Let’s see how much these resistors affect things, along with the contacts between the power supply and display boards, and the USB connector itself.


But first, I’ll check how accurately the output current is measured.
The power supply was loaded using an electronic load, so the current in the circuit remained stable.
1. At 0.5 A, it reads 0.51 A—very good.
2. At 1 A, it reads 1.03 A. It’s a little high, but well within the acceptable range.
3. At 2 A, it reads 2.08 A—a 4% difference, which is quite good for a simple device.
4. At 3 A, it reads 3.25 A. The difference is now significant. I suspect the resistors are heating up, so there’s not much point in measuring currents above 2–2.5 A in practice.


Let’s check the voltage drop at different load currents. Since we already know that the power supply outputs 5.19 V and that this voltage is stable, we’ll try to determine its maximum current.
The load current was increased in steps: 0.5–1–2–3 A. At 2 A, the output voltage was 4.84 V; at 3 A, it dropped to 4.66 V, which doesn’t meet the standard’s requirements (5% or at least 4.75 V). So the actual maximum current per port is 2–2.5 A.

People sometimes ask me in the comments how an electronic load differs from an ordinary load. This test gives an indirect illustration: the power supply’s output voltage clearly drops, while the current remains stable, making it possible to take more accurate measurements.


That’s enough torture for this power supply. Let’s move on to the conclusions.
Pros
Neat construction.
Load current is displayed for each output, as well as the total current.
It has an input filter.
Components are generously rated.
The power supply passed all the tests, including repeated short circuits.
Completely silent.

Cons
Some sloppy work by the manufacturer.
No output inductor.
Quick Charge would have been a welcome feature.

My take: this charger is reasonably well made. The heatsink is at the top rather than the bottom, and most of the components are generously rated. For example, they could have used a single diode assembly on the output, but installed two instead—though they forgot the thermal paste. The output capacitors could be better, but even as supplied, the charger should work just fine. The ability to display the current drawn by connected devices may be particularly useful, although most people will probably find this feature unnecessary.
On the downside, I’d point out the sloppy assembly (it reminded me of my previous review of an adjustable power supply), especially on the display board. Also, in my opinion, the price is a little high for a device with a current display but no QC function.
I think the device will work happily for a long time as supplied. If you do modify it, it’s best to replace the capacitors upstream of the inductor with higher-quality ones at the same time as adding the inductor.
All in all, another well-designed power supply with a few minor shortcomings.

That’s about it. I hope you found the review useful, and perhaps interesting too. As always, feel free to ask questions in the comments. If you spot any errors or inaccuracies, let me know.

The manager sent me a coupon, 6charger, which should bring the price down to 21.99

The product was provided by the store for review.