Test/review of Rock QC 3.0 30W 3 USB charger

HKJ · 2019-08-10T15:09:31.000Z

Rock QC 3.0 30W 3 USB charger

Official specifications:

Input: 100-240V 50/60Hz 0.35A
Max Power: 30W
Output (QC): 5V/3A, 9V/2A, 12V/1.6A
Output (USB): 5V/2A
Material: PC fireproof Material
Size: 25 * 45 * 52mm

I got it from Aliexpress dealer: ROCK Official Store

Measurements

Power consumption when idle is 0.4 Watt
Minimum QC3 voltage is 3.6V
Voltmeter can only show 5.0, 9.0 and 12.0V and do not show actual QC3 voltage.
All USB outputs has a common minus connection
The two standard USB outputs are coded as USB charger (DCP)
Q3 output is coded as Apple 2.4A, Samsung, DCP, QC3
Weight: 54.8g
Size: 89.4 x 45.3 x 26.6mm

The ammeter is moderately precise, but a bit optimistic. It shows the current for the QC output. The voltmeter do not show the actual voltage.

The top USB output can only deliver about 1.1A.

The same with the second USB output.

Can they reach the rated 2A when working together? No, it is still 1.1A

The output is the same at 120VAC

The QC output is rated for 3A, but cannot deliver more than 2.3A

The current is nearly the same at 9V

At 12V the maximum current is dropped to 1.8A, this fits with the 1.6A rating.

At 120VAC the maximum current at 12V is slightly above 1.6A

First I tried with 1A on USB and 1.5A load on QC, it only worked for about 22 minutes, then the QC output failed.

Reducing the QC current to 1A and trying again worked better.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.

HS1: 97.0°C
At 1A+1.5A the charger got very hot. HS1 is the QC transformer.

M1: 82.9°C, HS1: 86.3°C
HS1 is the QC transformer and M1 is the USB transformer.

HS1: 75.1°C
HS1 is the QC switcher.

HS1: 67.3°C
HS1 is the QC transformer.

HS1: 72.7°C

M1: 51.4°C, HS1: 85.1°C

At 0.5A the noise is 112mV rms and 726mVpp.

At 1A the noise is 138mV rms and 372mVpp.

At 0.5A the noise is 29mV rms and 723mVpp.

At 1A the noise is 40mV rms and 1015mVpp.

At 2A the noise is 12mV rms and 282mVpp.

At 9V 0.9A the noise is 52mV rms and 1138mVpp.

At 12V 1.2A the noise is 68mV rms and 1050mVpp.

Tear down

This type of charger is easy to open. Mount the base in my vice and give the top a whack with a mallet.

The charger is two partly separate switchers, they share the input fusible resistor (F1) and the two smoothing capacitors (EC1 & EC2).
The QC output has the switcher (U1) and opto feedback (U2) on this side of the circuit board and uses the red transformer (T2). The normal USB output uses the smaller white transformer (T1). The safety capacitor (CY1) is placed beside that transformer. On the output side is the smoothing capacitors (EC5 & EC6), the meter and the USB connectors.

This side has the bridge rectifier (BD1), the USB switcher (U5) and rectifier diodes for QC (D2) and USB (D3). The QC controller (U4: LP103S). The current sense resistor for the meter is here (R1: 0.025ohm)
There is some bad soldering/placement here (C4) and some solder balls (R4 and many other places).

The meter module is very compact with a microprocessor/voltmeter chip and a regulator (U2: HT50, probably 5V).

On this side is the display and a few resistors.

The distance between mains and low volt side is supposed to be above 6mm, here it is below 2mm.

The charger passed the 2830 volt test, but failed the 4242 volt test between mains and low volt side, this makes it unsafe for 230VAC countries.

Conclusion

This charger has low production quality, is way below specifications and is unsafe.

Notes

The charger was supplied by a reader for review.

Index of all tested USB power supplies/chargers
Read more about how I test USB power supplies/charger
How does a usb charger work?

s5610 · 2019-08-10T17:22:00.000Z

“Gnome” transformer, DIP8 PWM, 817 optocoupler - did you see such power supply? You saw them all )

HKJ, you can pass by with tests on trashy looking interior, we will understand you. Save the time

HKJ · 2019-08-10T18:17:49.000Z

s5610:

“Gnome” transformer, DIP8 PWM, 817 optocoupler - did you see such power supply? You saw them all )

HKJ, you can pass by with tests on trashy looking interior, we will understand you. Save the time

Sorry, I am not sure what you mean.
I do not know how a charger looks inside before testing it, opening the charger is first done when I am done with all my tests.

I do believe testing bad chargers is important, how can you know it is a bad charge without testing it? I will admit that it is fairly easy to guess in some cases, but some of my guesses have been wrong!

s5610 · 2019-08-11T16:22:50.000Z

HKJ:

I do not know how a charger looks inside before testing it, opening the charger is first done when I am done with all my tests.

Would it be vice versa, first disassemble then testing, could potentially save time. E.g. when we see 1 mm gap between mains and secondary circuit, is it worth to test further… I’m sure after hundreds of reviews you can predict the result roughly at a glance on what components are used. But sure it wouldn’t be so excite when you test “a black box”, and, what is more important, your project is about testing, not choosing+buying. It’s educational thing.

P.S. Can you give a hint, when you were wrong? A bad looking PSU, but good results.

HKJ · 2019-08-11T18:42:23.000Z

s5610:

Would it be vice versa, first disassemble then testing, could potentially save time. E.g. when we see 1 mm gap between mains and secondary circuit, is it worth to test further…

I sometimes damages a charger when opening it, so I have to test first.
I do also believe it is interesting to see how bad the bad chargers are.

s5610:

P.S. Can you give a hint, when you were wrong? A bad looking PSU, but good results.

Yes, it sometimes happens a cheap charger passes all tests.