BlitzWolf 24W Dual wall charger



Official specifications:

• Power3S Technology:Intelligently identifies the electronic device and speaks the language it needs for full speed charging.
• Electricity-24W of Power:Smart digital power output,can charge any two smartphones or tablet devices simultaneously at top speed.
• Safe and Sturdy Design:Lightweight,compact and easily portable.
• Input: AC 100-240v 50/60Hz 600mA
• Output: 5V /4.8A (Each 2.4A MAX)
• Size: 53 X 53X 25mm /2.09X 2.09 X0.98inch
• Color: White

I got it from Banggood



I got this charger in a fairly plain cardboard box. The square one is the US version, the other one is the EU version.



The box contained the charger and a instruction sheet.



I got four versions of the charger: black/white and US/EU, because I got the white US first I did most test with that version.










What cannot be seen on the pictures is the blue led inside the charger, this means there is a blue glow from the two usb ports when the charger is powered.



Measurements

• Power consumption when idle is 0.2 watt at 230VAC and 0.15 watt at 120VAC
• All outputs are in parallel.
• No individual port overload protection.
• Usb port coding is automatic selected (Up to Apple 2.5A).

Good efficiency, but no individual overload protection on the ports.



The common overload protection kicks in at about 6A.





Same as above, but with the other supplies.



With 120VAC supply the overload protection kicks in a little bit earlier.



No problem running at 4.8A for one hour. The two fall-outs at about 47 minutes matches with when I moved the charger around to get the IR photos, i.e. the US mains plug and adapter combination did not maintain a stable connection.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.



M1: 49,0°C, M2: 46,5°C, HS1: 65,5°C
HS1 is the rectifier.



M1: 53,5°C, M2: 52,1°C, M3: 46,5°C, HS1: 55,9°C
HS1 is either the transformer or the two small diodes (D3, D6) under the transformer.



M1: 51,7°C, M2: 53,3°C, M3: 43,8°C, HS1: 60,5°C
This time HS1 is the transformer.



M1: 41,6°C, M2: 44,5°C, HS1: 55,1°C



M1: 58,1°C, M2: 50,7°C, HS1: 62,5°C
HS1 is the rectifier.



At 0.5A the noise is 19mV rms and 650mVpp.



At 2.5A the noise is 19mV rms and 550mVpp



At 5A the noise is 20mV rms and 570mVpp.



At 5A the noise is 13mV rms and 300mVpp.



Tear down



I could not open this with pressure, I had to cut it open.



The mains is attaced with the red and black wires, it goes directly to a fuse and after that a common mode coil. There is also a normal inductor. U1 is the switch mode controller IC that controls the transistor (It has its back to the slot).
On the low volt side is a rectifier and a inductor (L4). Between the two usb connectors is the automatic usb coding IC (U4).
The blue part is a safety capacitor and below it is the optical feedback IC.



On the first picture the common mode coil and the inductor can be seen. On the second picture the blue led between the usb connectors and the safety capacitor with the opto coupler below it can be seen.



The rectifier can be seen here and it does not have a heatsink, this is very uncommon for a 5A usb charger, but there is an explanation.
The input fuse is the red block, it is a 2A fuse.



On the bottom of the circuit board is the bridge rectifier. U3 is the controller for the opto feedback. The secret for leaving out the heatsink can be seen here. The rectifier is not a diode, but a transistor and U2 is probably the chip controlling it, this is called synchronous rectification and is much more efficient than a diode.





There are two places where mains and low volt side are a bit close, but not closer than the rules say.




The slot in the circuit board is used for a plastic shield that secures very good distance for most of the parts.


Testing with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.



Conclusion

This is a good usb power supply with only minor details that could be better:
I would have liked the blue led visible from outside, even with both usb outputs in use.
The peak noise is a bit high (but I doubt it will interfer with anything).
The charger can deliver up to 6A into a single usb plug, this is a bit too much.



Notes

All measurements are done with the white US version at 230VAC, except where otherwise noted.
The usb power supply was supplied by Banggood for a review.

Index of all tested USB power supplies/chargers
Read more about how I test USB power supplies/charger