I have a PWM fan control project I am working on and I want to bench test the MOFET I chose. The project will be run on my truck in a 13.8 volt system. The fan will pull about 25amps and I believe the manufacture said it was a 265 watt motor. I was thinking of bench testing it with a dummy load but am unsure of how to do this. I would really do not want to run the test with the fan on for a day or two. Any help will be grateful.
25 Amps at 13.8V would be 345 Watts. You need a 345 Watt dummy load and a 25 Amp/13.8V power supply. Perhaps you can make the dummy load from a bunch of 55W and 60W headlight bulbs. Put them in parallel.
I was thinking of buying a 300 watt resistor from Digikey. I am unsure if this will work and if so what value it should be.
johnwasser:
25 Amps at 13.8V would be 345 Watts. You need a 345 Watt dummy load and a 25 Amp/13.8V power supply. Perhaps you can make the dummy load from a bunch of 55W and 60W headlight bulbs. Put them in parallel.
Oh yes, auto headlights are a much more economical and available option for a 'dummy load' Vs 300+ watt resistor.
I've seen some impressive power MOSFETs used as 'programmable dummy loads' using very large heat sinks with induced fan air cooling, but again auto lamps are cheap and available for one-time testing requirements.
Lefty
tresguey:
I was thinking of buying a 300 watt resistor from Digikey. I am unsure if this will work and if so what value it should be.
You need about a 0.0425 Ohm resistor. Looks like DigiKey only has them down to 0.1 Ohm for about 35 to 40 dollars each. I guess you could use lower power resistors in parallel to get the resistance down.