Test/Review of USB Load resistor 1A-2A usb output (Discharger3) (2xWhite resistor)

EDC Gear for Flashlight Carriers USB Power Devices
1

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







Official specifications:

  • USB male load 1A / 2A switch selection

  • 10W 5R cement resistor, no odor

  • PHR foot switch selection 1A or 2A


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 200°C and 300°C 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.













Load testing

  • This type of load is only designed for 5V input.

  • Current change during 30 minutes with 1A load is 0.009A, i.e. 0.9%

  • Current change during 30 minutes with 2A load is 0.028A, i.e. 1.4%

  • The usb output has a working data connection to the input.




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



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



M1: 190,7°C, M2: 153,5°C, M3: 94,1°C, M4: 87,8°C, HS1: 204,5°C
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: 73,3°C, M2: 60,0°C, M3: 86,5°C, M4: 129,9°C, HS1: 225,3°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 especially when both resistors are used.
It is not a good idea to touch it when it is working.


Notes

Expect very similar performance from all resistive loads with two white square 10W 5ohm resistors.
2

Does it smell while in use?

3

Not much. All the resistor loads I tested could be smelled, but none where bad (I have one more).
Put your finger on any of them and you could probably smell fried fingers.

I like the simple resistive load (I use them myself, but in better quality), but I do not like the high temperature, why not use one cent more and mount the resistors correctly.
I now the answer to that one: it is China and there the question is how to save one cent more.

4

I kind of thought it was the bendy nature of the leads when mounted too high. I suspect many users would just grab and pull, if it wasn’t run long enough to burn, and mounting them high would allow them to move if not supported by other structures. There is also the clearance to consider as mounting them high might block something or prevent them from being inserted in awkwardly placed / upside down ports.

As for the smell, this might make it better, especially if testing around lunch time.

KuoH

5

There would have to be a support structure and a few mm in the air will help very much. The way they are mounted now there is a good probability that the circuit board will be charred over time.

Long time ago I used this kind of ceramic beads for smaller power resistors: