LDNIO DL-AC59 Dual usb 2.4A



Official specifications:

• Input: 100-240V AC,50/60Hz
• Output: DC 5V 2.4A
• Weight: 50g
• USB port: Dual USB port
• Compatible: USB 2.0 Power Plug.

I bought it from banggood.com, this is not a super cheap model, but cost a bit more. Is this enough to make it safe?



This charger arrived in a retail package.





The two ports are marked "For iOS" and "For android" with some small and nearly invisible letters



Measurements

• Idle power is 0.17 watt
• Output iOS is coded as Apple 2.5A
• Output Android is coded as usb charger (DCP)
• Outputs are in parallel.
• USB connectors have a hidden blue led between them.

The two ports are the same, i.e. output voltage is very stable and the efficiency is around 80%, the charger has overload protection at 2.4A. This looks good.



One hour with 2.4A load is not problem.
The temperature photos below are taken between 30 minutes and 60 minutes into the 1 hour test.



M1: 51,7°C, M2: 48,4°C, HS1: 63,4°C
HS1 is probably the transformer.



M1: 54,0°C, M2: 59,5°C, HS1: 73,2°C



M1: 53,7°C, M2: 48,4°C, HS1: 59,1°C



M1: 53,1°C, M2: 52,0°C, M3: 50,3°C, HS1: 53,8°C



M1: 65,3°C, M2: 54,6°C, HS1: 72,8°C



There is some noise at 0.5A with 30mV rms and 420mVpp.



It increases with load, 25mV rms and 460mVpp at 1A.



The peak has increased even more, 30mV rms and 440mVpp at 2.5A.



Tear down



This was easy to open, just some pressure on it and it popped open.



It looks very compact, but it do have a couple of good details: There is a fuse, the switcher transistor is fairly large and the rectifier has a heatsink.



Here the rectifier heatsink can be seen, it is a piece of circuit board. Between the two usb connectors the blue led can be seen.
The capacitor marked Y1 is the safety capacitor.



The safety capacitor is easier to see here and the 105°C capacitors. At the mains input the fuse can be seen (F1).



On the bottom is the bridge rectifier and the mains switcher controller IC (U1).
This model does not use opto feedback, but as can be seen on the load sweep it does fine without.



The safety is always interesting with a compact construction. When using slots in the circuit board the distance for air can be used, i.e. 4 mm, but here there is only 3mm. There is a couple of other places where there also might be problems.
A silly problem with this usb power supply is the golden ring, the gold paint is a conductor and makes a nice path from mains to low volt side with only some small distances for the current to jump.



The charger passed a isolation test with 2500 volt, but failed a 5000 volt test, this makes the charger acceptable for 110VAC usage, but doubtful for 230VAC usage. With a 230VAC plug in the charger it is not acceptable.



Conclusion

There performance of this usb power supply is good, but safety is not that good.



Notes

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