USB Load resistor 1A-2A


Official specifications: I bought from ebay dealer: finetech007

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.





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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 drop due to temperature.


M1: 74,2C, M2: 99,2C, M3: 70,8C, HS1: 213,5C
One resistor gets fairly hot.


M1: 66,0C, M2: 69,3C, HS1: 112,4C
The tinned area on the back will equalize the temperature, but do not really radiate any heat.


M1: 255,9C, M2: 253,5C, M3: 139,1C, M4: 115,7C, HS1: 275,6C
Two power resistor this close will heat each other and gets very hot.
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: 100,3C, M2: 101,7C, HS1: 160,1C
Again the radiation from the backside is limited.


The load works as expected and is an easy way to test usb power banks (together with a usb meter), but this model really need an external fan to supply lots of cool air.
It is a very bad idea to touch it when it is working.


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