USB Load resistor 1A



Official specifications:

• Type: 1A discharge resistor.
• Used For: Power bank / Battery Capacity testing.
• Brand new and high quality.

I bought it on ebay some time ago.

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



This type of load is very simple, two big power resistors and a led to show if there is any power supplied to it.













Load testing

• This type of load is only designed for 5V input.
• Current change during 30 minutes with 1A load is 0.005A, i.e. 0.5%

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: 165,5°C, M2: 87,0°C, M3: 57,4°C, M4: 171,9°C, HS1: 181,2°C
The resistors gets fairly 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: 124,5°C, M2: 63,8°C, HS1: 132,1°C



Conclusion

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.
It is a bad idea to touch it when it is working.



Notes

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