I have tested this size of charger before and it was not very good. This model here is upgraded with two usb connectors and more output current. How much does this upgrade improve it?
Official specifications:
Input: 100-240V ~50/60Hz Max0.5A
Output: 5.0V 3100mA
No retail package for this charger, only a simple plastic bag.
Not much design in this adapter, it is just a box with a power plug and a couple of usb socket.
Measurements
USB coding on 1A is usb charger (DCE)
USB coding on 2.1A is Samsung tablet
Idle power consumption is 0.15W at 230VAC
Idle power consumption is 0.12W at 120VAC
The power supply is supposed to be a 3A supply, but it can only deliver 0.6A at 120VAC, this is not very impressive.
Using it with 230VAC it can deliver nearly 1A, still way below specifications and I did not see any overload protection.
One hour with 0.6A load works fine.
M1: 35,8°C, HS1: 47,2°C
It gets warm, but it is acceptable.
M1: 35,7°C, M2: 38,5°C, HS1: 43,3°C
With 230VAC and 0.9A load it also works fine.
M1: 42,3°C, HS1: 61,3°C
But it do get considerable warmer.
Tear down
The charger is very compact constructed and I cannot see any isolating elements in it.
The two leds are color cycling leds, i.e. they will continuous change color when the adapter is powered.
The two red circles shows how close mains and low voltage side is to each other, I will estimate about 0.5mm, this is way to low for both US and EU safety.
The charger failed a isolation test with 2500 volt, this makes it doubtful to use on mains power anywhere in the world.
Conclusion
This charger has considerable less performance than rated, but that is only a minor issue compared to the bad safety.
With this type of charger there is a risk of making the headlines.
Great stuff. I keep seeing little usb chargers in the shops, quite cheap, but think “I wonder what HKJ would make of this junk?”. Thanks for the warning.
Good to see how bad these things can be designed. Thanks to your teardowns I have some idea about how a safe low/high voltage design should look like.
(I recently did a teardown on an IKEA led bulb because I wanted to use the leds for a DIY-project, and the circuit board clearly showed a good separation between high and low voltage)
I wonder if I could have your opinion on the charger pictured below. It appears to not have much separation between the 120 (red wires) and the low voltage. For scale, it is pretty much the size of the unit you just tested.
It is basically the same, my guess is that two wires in the four wire flatcable are mains and the two other are low volt side, i.e. way to little isolation distance.
Brand names and a few other, you can check my website or search here.
I plan on testing a couple more of these power adapters, including some high power ones with many usb outputs. I anybody has some suggestions, please send a link to the item in a shop.
