Weird fan problem

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Ontario, Canada
Arrma RC's
  1. Fireteam
  2. Granite
  3. Granite Mega
  4. Infraction
  5. Mojave EXB
  6. Nero
  7. Notorious
  8. Typhon 3s
Can anyone explain this. I thought the fan wasn't working but then tested again off the car and it worked. The second it goes on car it stops. When pushing it on slowly I can actually hear it slowing down and losing power.

Only things I can think it's it's either some weird ground issue or the magnets from the motor is stopping the fan????
 
Magnetic interference from the motor magnets the fan is not shielded well and I'm guess really strong motor magnets put a 3D printed or some kind of grill on the heat sink behind the fan and use a longer screw.
 
It looks like the motor magnets are causing major interference..

All you have to do is rotate that motor (choose the other two motor mounting holes) and it should help.
 
That's a good one. I'm stumped.

Check your wire under the fan, might be shorting to the motor. 🤷‍♂️
Checked that, wires look good.
Is there anyway the fan can be binding on something when it's on the motor?
That's the first thing I thought too. So tried bending the mount open and closed while it was running and it never stopped.
It looks like the motor magnets are causing major interference..

All you have to do is rotate that motor (choose the other two motor mounting holes) and it should help.
Ok will give that a try tomorrow. Might also pull the fan off and put just the fan beside the motor to see if different locations help.
Maybe this is why brushed motors don't come with fans?
 
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Yup Definitely a magnet thing.

Out of curiosity, does anyone know if any rtr brushed rc every came with a motor fan?

From what I can recall... They were always attached with a passive heatsink fins of some sort..
 
Yup Definitely a magnet thing.

Out of curiosity, does anyone know if any rtr brushed rc every came with a motor fan?
Arrma EXB line comes with a heatsink that is built for there fan to fit so yes kind of.

Space it out from the heat sink till it works air flow is still good and the heat wink will draw heat increasing surface will help with cooling provided there is no insulator between it and the motor

Air flow is air flow in most cases its not about static pressure but CFM the amount of air moved. It dos not mater how hard you blow on it but how much heat the air can absorb and then getting new air to it. Some fans run better with and air gaps as there not made to have the best static pressures and will get less CFM up against an object. See the difference in 120mm and 140mm PC fans 120 tend to be higher static with lower CFM were 140 are higher CFM and lower static. In a lot of cases the depth of fan blade to fan blade diameter will give you a guess at static to CFM. With larger diameter giving more boost to CFM and blade depth giving more static pressure.

Hope this helps
 
Just to add extra confusion.
It works now when held closer but stops when only touching 2 points.

Also realized the orientation of the fan has an effect. It will not run, then if I turn 90deg clockwise it works.

So ended up mounting it like that with some small spacers just in case but at this point I think the fan is alive and just messing with me. 😧

 
Turn the fan 45°
(You'll need a fan adaptor that would allow it to be in that orientation though.)
 
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