Qihang Fast Charger QH-Z03

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Official specifications:
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It arrived in a partial transparent plastic box.

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Measurements


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The charger is rated for 3A on 5V and deliver about 3.2A, this is fine.

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It works the same on 120VAC.

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At 9V it matches the 2A rating very nicely.

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At 12V it is rather close to the 1.5A rating.

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It looks better at 120VAC.

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The overload protection must be temperature sensitive, it kicked in after 8 minutes at 2A load on 9V.

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Reducing the current to 1.8A and it could handle a 1 hour test.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.

Temp7340

HS1: 73.7C
HS1 is transformer.

Temp7341

M1: 56.4C, HS1: 62.2C

Temp7342

M1: 47.4C, M2: 39.4C, HS1: 50.5C

Temp7343

HS1: 57.4C

Temp7344

HS1: 72.7C

10ohm

At 0.5A the noise is 48mV rms and 1835mVpp.

5ohm

At 1A the noise is 42mV rms and 829mVpp.

2ohm

At 2.5A the noise is 54mV rms and 1421mVpp.

10ohmQC9V

At 0.9A the noise is 49mV rms and 1156mVpp.

10ohmQC12V

At 1.2A the noise is 69mV rms and 1165mVpp.



Tear down

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Putting a lot of pressure on the top of the charger with my vice made the lid pop out.

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At the input is a fusible resistor in heatshrink, the two mains smoothing capacitors (C1 & C2) has a inductor (L1) between them. There is a safety capacitors (CY1) between mains and low volt side.

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On this side is the bridge rectifier (BD1), the mains switcher (ATC9560), opto feedback, a rectifier diode (D3: probably DK5V85R1... synchronous rectifier), a QC controller (U3: Maybe LP103) and a reference (U4).

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The distance between mains and low volt side is fine.


Testing with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.



Conclusion


The charger is a fairly standard QC3 charger with good efficiency, the safety look fine. Like many cheap chargers it do not have any mains filtering, this means the radio emission it probably way above the legal limits.




Notes

The USB 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?