USB Load resistor 1A-2A usb output (Discharger3)


Official specifications: I bought from ebay dealer: trade021

The most interesting detail about this type of load is how hot they get, some power resistor has a working temperature between 200C and 300C when fully loaded.


This type of load is very simple, two big power resistors, one permanently connected, the other controlled by the switch and a led to show if there is any power supplied to it.
I cannot guess what the purpose of the usb output is, adding more load is not really necessary.





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Load testing

Being a resistor the current will depend on voltage.


As expected the load current and power is stable with a resistor, except for a small change due to temperature.


M1: 56,7C, M2: 65,8C, M3: 84,0C, HS1: 156,1C
One resistor gets fairly hot.


M1: 73,7C, M2: 53,8C, M3: 44,4C, HS1: 149,4C
The backside of the circuit board is also hot and is helping radiating the heat.


M1: 190,7C, M2: 153,5C, M3: 94,1C, M4: 87,8C, HS1: 204,5C
With both resistors active they get rather hot, because they are heating each other.
The correct way to mount power resistors is a bit above the board with some distance between. These resistors are only running at half their rated power, but they cannot get rid of the heat.


M1: 73,3C, M2: 60,0C, M3: 86,5C, M4: 129,9C, HS1: 225,3C


The load works as expected and is an easy way to test usb power banks (together with a usb meter), but this model need an external fan to supply lots of cool air especially when both resistors are used.
It is not a good idea to touch it when it is working.


Expect very similar performance from all resistive loads with two white square 10W 5ohm resistors.