Hello, I just picked up a PDM 15 and while configuring the outputs I noticed a large red triangle saying not to PWM any device drawing more than 10A during normal operation. I have 3 items that I am pretty sure pull >10A in normal service, but I have not datalogged them yet.
1st items are 2x SPAL 30102800HO fans and the other item is a Weldon 2025-A fuel pump.
The fans I wanted to use PWM to slowly ramp up the duty cycle as engine temp rises. I had originally planned on using 2 outputs for each fan. SPAL documents show anywhere from 24.5A-35.8A draw depending on static pressure. I doubt I am anywhere near that max static pressure as it would be almost no airflow. Worst case is probably 30A each.
The 3rd item is the Weldon 2015-A fuel pump which, according to the datasheet that came in the box, can pull close to 16-17A around 50 PSI. For the fuel pump I planned on initially using simple RPM > 2500 = 100% duty. But later on I wanted to use MAP or injector duty cycle to determine the PWM output.
Long way to get to my question, is 2 output pins per device enough to be able to use PWM? If I have to go to 3 I'll need a PDM25 making this newly purchased PDM15 a paperweight.
How did you resolve this situation? Especially with fuel pump? Im sure that my pump draws 20A.
your best off wiring them in and then checking the amount of current they draw. I have 3 fans on one of the radiators each one said they draw 120 watts of power. So that should have realistically been 360 watts in total 30 amps. But in reality they only draws about 5-12 amps. Again with my Bosch 0044 FIP and red top facet fuel pump these together only pull somewhere in the region of 6-10 amps where I was expecting about 15 amps. I'm not sure of that maximum of 10 amps I've not seen it in the documentation but then again I have got the PDM 25+, that may be slightly different.