heater fan motor

PostPost by: seniorchristo » Sun Jan 29, 2023 3:37 pm

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
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PostPost by: alaric » Mon Jan 30, 2023 10:30 am

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.
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PostPost by: john.p.clegg » Mon Jan 30, 2023 11:14 am

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

John ;-)
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PostPost by: Craven » Mon Jan 30, 2023 11:57 am

Reverse the supply polarity, later motors will change rotation direction indicating a later and improved design.
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PostPost by: seniorchristo » Wed Feb 01, 2023 1:39 am

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. :)
Last edited by seniorchristo on Wed Feb 01, 2023 12:27 pm, edited 1 time in total.
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PostPost by: h20hamelan » Wed Feb 01, 2023 2:14 am

I do enjoy soaking electric motors in ATF overnight
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