I just received a USB passive load. It’s basically 2 resistors connected to the USB power wires in parallel, each with a switch in series:
It can draw approximately 1, 2 or 3 amps (depending on switch positions) from a 5 volt USB source.
The resistors can dissipate 10 Watts, and will become very hot.
The resistor for 1 amp (4,7 ohms, tolerance 5%) maxed-out my FLIR One thermal camera (> 150 °C), but I could measure around 220°C (that’s close to 451°F) with another thermal imaging camera.
The second resistor (2 amps: 2,2 ohms, tolerance 5%) maxed-out that other thermal camera too: this one got hotter than 280°C.
I’m referring to 451°F, because presumably, that’s the temperature to ignite paper. Something I’ll have to test out in safe conditions.
I also measured the resistors, and they are well within tolerance:
Here is a short thermal imaging video of the first resistor heating up:
Didier Stevens 
Very nice cigar lighter, Didier
Comment by Antonio Gallego — Monday 28 September 2020 @ 14:09
Nice one, Antonio 🙂
Comment by Didier Stevens — Monday 28 September 2020 @ 16:27
I see 4 cables. My multimeter has 2?
Comment by Anonymous — Tuesday 29 September 2020 @ 7:19
What is the benefit to this device? What are you intending to use it for?
Comment by Greg Kelley — Tuesday 29 September 2020 @ 19:48
This device is used to consume electrical power. You can use it to test devices that deliver electrical power. I’ll use it to test powerbanks.
This is a very simple and cheap device, that uses a passive element (resistor) to consume electrical power.
There are also more advanced, active devices: https://en.wikipedia.org/wiki/Programmable_load
Comment by Didier Stevens — Wednesday 30 September 2020 @ 16:01
That’s a 4-wire method: https://en.wikipedia.org/wiki/Four-terminal_sensing#:~:text=Four%2Dterminal%20sensing%20(4T%20sensing,%2Dterminal%20(2T)%20sensing.
Comment by Didier Stevens — Wednesday 30 September 2020 @ 21:03
Here is a video I just made on the 4-wire method: https://www.youtube.com/watch?v=yVQAR1mFFDM
Comment by Didier Stevens — Friday 30 October 2020 @ 15:32