Rock QC 3.0 30W 3 USB charger

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Official specifications: I got it from Aliexpress dealer: ROCK Official Store

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Measurements
current

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.

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The top USB output can only deliver about 1.1A.

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The same with the second USB output.

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

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The output is the same at 120VAC

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

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The current is nearly the same at 9V

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

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

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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.

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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.

Temp7003

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

Temp7008

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

Temp7009

HS1: 75.1C
HS1 is the QC switcher.

Temp7010

HS1: 67.3C
HS1 is the QC transformer.

Temp7011

HS1: 72.7C

Temp7012

M1: 51.4C, HS1: 85.1C

10ohm

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

5ohm

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

10ohmQC5V

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

5ohmQC5V

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

2ohmQC5V

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

10ohmQC9V

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

10ohmQC12V

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



Tear down

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

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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.

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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).

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

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On this side is the display and a few resistors.

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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
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