heater fan motor

[seniorchristo]

I have three fan motors to choose from for my Plus2. They all seem to run ok on both resistor speeds. When I check the individual motor resistance of the three motors, (bypassing the 2 speed resistor), I get values of 3.8 ohms, 7 ohms and 13 ohms. Why the big difference and which would be preferable to use? Thanks

[alaric]

Hi. It depends on the winding design I think. I believe the stall current will be determined by the resistance that you have measured, but once running the power and current taken depend on the winding and magnet, and there will be back emf involved. Sorry not to be of any more help; it's been a long time since uni I'm afraid. I suggest you put the fan on them in turn and see which gives the greater air flow.

All the best.

Sean.

[john.p.clegg]

Stick 12v across them in turn , and with a gloved hand grab the spindle and try to stop them....best man wins..

John

[Craven]

Reverse the supply polarity, later motors will change rotation direction indicating a later and improved design.

[seniorchristo]

All three motors run the same direction regardless of polarity. The amperage draw is 2.9, 4.1 and 5amps. The one with the low amps runs fastest so that's the one I'll use.

[h20hamelan]

I do enjoy soaking electric motors in ATF overnight