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LED on/off switch, lights up when it's off, while under acceleration.


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I recently installed a couple fans to the inside of my radiator on one of my vintage cars.  I just wanted the fans as back up fans for parades or traffic jambs.  I wired them in so they come on when I flip the switch rather than having a controller.  I wired them in separately so I have two switches. As the diagram shows the power to the switches will turn odd once I shit off the ignition.

I noticed that when I reach a speed of 35 mph, the led light starts come on and gradually gets brighter the faster I go.  But not as bright as when I turn on the switch.  

What's that all about???

Do you think it would make a difference if I reverse the wires going to the switch?

20240215_083703-r.jpg

Edited by timecapsule (see edit history)
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10 minutes ago, bob staehle said:

Sounds like your fans are generating enough current to lite

the led lights. The faster you drive the more they put out.

But with the switch in the off position, there is no power going to the fan.

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44 minutes ago, timecapsule said:

The fans are on the inside of the radiator.

Air moves through the radiator, doesn't it?

If it didn't your radiator would not cool.

 

I agree with the others, sounds like the fans are generating enough voltage to dimly illuminate the LED.

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24 minutes ago, zepher said:

Air moves through the radiator, doesn't it?

If it didn't your radiator would not cool.

 

I agree with the others, sounds like the fans are generating enough voltage to dimly illuminate the LED.

I'm not totally convinced, however I also had that thought when I first saw them come on. 

I have a fan on the engine as well.  One reason I mounted the two fans on the radiator is because The engine sits low in respect to the radiator.  So low that about 3 inches of the fan blades are actually below the radiator so I wanted to have more air being drawn through the radiator.  So I mounted the two 8 inch fans on the radiator above the engine fan blades as shown in the picture below.  After noticing the LED lights coming on when driving, I wondered about what you guys have said, and if what has been said here, could be happening.  So while parked I fired up the car and revved it up to around maybe 2500-3000 rpms.  The two 8 in. fans didn't budge.  The engine fan, as you can see is very close to those 8 inch fans.  

Tomorrow I'll try forcing air directly on the fans with an air nozzle from my compressor and see if the  LED lights on the switches come

on.   I know lots of guys that have add on electric fans mounted on their Hot Rods and no one has ever casually mentioned that the LED lights on their switches are coming on when the fans are turned off. 

If this is actually happening then surely there is a way to channel that energy back into the battery. 

Edited by timecapsule (see edit history)
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Assuming that you guys are correct and voltage is being produced by the rotation of the fan.  How would that voltage find its way back to the LED at the end if the toggle switch?  When the switch is turned off,  I don't believe that there is  continuity between the LED light at the end if the toggle and the wire that goes to the fan.  I would think that the LED would have continuity with the ON side of the switch only. 

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I don't see a picture in either of your posts.

 

If you used a relay between the fans and the battery and had the relay operated by a circuit run through your LED toggle switch, the switch would not light up with fan rotation.

It would be a circuit like this.

cb12f2b2d9fa2eebf713b3cd7d05f0b2.jpg

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6 minutes ago, zepher said:

I don't see a picture in either of your posts.

 

If you used a relay between the fans and the battery and had the relay operated by a circuit run through your LED toggle switch, the switch would not light up with fan rotation.

It would be a circuit like this.

cb12f2b2d9fa2eebf713b3cd7d05f0b2.jpg

I didn't want to go over board with the wiring.  I just wanted an on /off switch and some protection with a breaker.  Are you saying that my wiring is wrong? 

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Likely the LED is wired to the switch terminal that the fans are, too. The other side of the LED is connected to ground, so when the fans turn fast enough, the LED lights up. I had this happen with the same setup using a switch with an incandescent pilot bulb. I wouldn't worry about it, it shouldn't hurt anything and whenever you see the dimly lit switch, you'll know that your fan motors are good.

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9 hours ago, timecapsule said:

I didn't want to go over board with the wiring.  I just wanted an on /off switch and some protection with a breaker.  Are you saying that my wiring is wrong? 

 

Your wiring is not wrong, per se, but you are putting a lot of current through that LED switch.

It would be safer to have all of the high current stuff under the hood and use the switch for the very low current side of the relay.

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1 hour ago, zepher said:

 

Your wiring is not wrong, per se, but you are putting a lot of current through that LED switch.

It would be safer to have all of the high current stuff under the hood and use the switch for the very low current side of the relay.

I understand what you're saying, thanks.  However, I am using #10 for all the wiring except the ground wires which are #12.  Does that make it a little safer?

If I used a 4 prong relay as in your diagram, how would I wire it in given what I'm using  in my drawing?  My switches have two terminals plus a ground terminal.  I also have them wired separately and I turn them on one at a time so as not to create too much of a draw all at once.

 

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6 hours ago, 28 Chrysler said:

Switch the wires on the switch.

The LED one lead is grounded the other lead is connected to the switch terminal that is connected to the fan 

My mistake Put a diode on it to block the voltage from the fan.

I tried that, but with the wires reversed, once I turned on the ignition, the LED light came on full brightness.  When I flipped the switch and turned on the fan, the light stayed bright.

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  • timecapsule changed the title to LED on/off switch, lights up when it's off, while under acceleration.

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