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Discussion Starter #1
I had the idea to run a couple case fans over top of an amplifier. I was playing around in the shop today with an Alpine head unit and connecting the fan to it. I noticed if I connect it to the yellow wire of the Alpine it will power the fan full time, but if I connect it to the remote turn-on it will turn on and off with the head unit.

Is it OK to power the fan like this? The sticker on the fan says " 0.33A" so it's drawing about 1/3 of an Amp. But would it be OK to daisy-chain from the amplifier's remote input to 2 fans? Or will that be too much for a remote turn on wire? I am using a Wavtech line out converter that supplies the remote turn-on to the amplifier now by signal-sensing from the speaker level inputs.

Also, what orientation do you use for the fans? Blowing air on the amplifier, or blowing air away from the amplifier? I have fooled with computers a lot over the years, and one thing I've noticed is that a lot of fans are exhausting air, or blowing the hot air away from the component rather than blowing air on to it. I'm not going to be using a push/pull setup...just a straight over-the-top setup. So I can either have it blowing air on the amp or away from it.
 

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Safer to use a relay that's switched on with to the accessory/remote turn on. Relays are inexpensive and easier to replace a relay than a radio
 

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Discussion Starter #3
Safer to use a relay that's switched on with to the accessory/remote turn on. Relays are inexpensive and easier to replace a relay than a radio
Is running a case fan any different than turning an amplifier on? Or is it because the signal to turn the amp on is only "temporary" where the case fan will be constantly powered by the remote wire?

This is one of those things I don't "have" to do. It's just me messing around seeing what's possible. And I was going to do it in my son's car because I thought he might think it was cool having some orange LED fans. But if I have to add a relay and expect him to turn it off and on then it's not worth doing. He's not into it enough to care to flip a switch and turn the fans on. I wanted it to be something simple that just does its thing without needing anything from anyone.
 

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The remote turn has constant power on it once the unit is on. Amps draw very little current for the turn on signal. Radios are usually putting out 0.5A on the remote wire max. The relay will not use an external switch. You wire constant battery, ground, and remote turn on. Output power to fans will switch on when it gets the remote signal the same as your amplifier.
 

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Discussion Starter #5
The remote turn has constant power on it once the unit is on. Amps draw very little current for the turn on signal. Radios are usually putting out 0.5A on the remote wire max. The relay will not use an external switch. You wire constant battery, ground, and remote turn on. Output power to fans will switch on when it gets the remote signal the same as your amplifier.
Any tips or links on adding a relay?
 

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Any tips or links on adding a relay?
The above link is perfect. Just look for automotive spdt 12v relays at parts express, Amazon, local auto parts store. You're creating a turn on power source that's triggered by your radio, but the power is actually coming from the battery through the fused constant 12v. Most relays like these can accommodate 20+Amps of current so you have plenty of juice to turn on amps, run fans, lights etc.
 

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Discussion Starter #8
here ya go:

just remember to fuse the constant 12 volt input to the full load of whatever you're powering
The diagram seems easy enough to follow. To make sure I'm following this correctly, I would run a power wire from the relay to the fused distribution block I have in the trunk.

I run a ground from the relay to a ground location (where I have my amp and LOC grounded?).

I run the remote out from the LOC to the remote input of the relay. I don't have a remote turn-on from the HU since it's factory; I use an auto turn-on for the LOC and, in turn, the LOC turns the amp on.

From there, I use the last connection on the relay to run to anything I want to turn on or power, like the amp turn-on, fans, LED strips.

Is that it? The last question I have is about fusing. If I'm running the power wire from relay to the fused distribution block I know I have to insert a fuse. But am I fusing the total of the relay or what's connected to it? That might be confusing but the relay in the link says "30 amp SPDT relay". Does that mean I would use a 30 amp fuse in the block? Or would I use the total of what's connected to the relay? So if I had 4 fans and an amp turn-on say I'd be close to 5 amps then I'd use a 5 amp fuse?
 

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Inline fuses protect wire.

Each piece of equipment should have it's own individual fuse if your goal is to protect equipment. If you have a combined draw of 2 amps and fuse it for that and one fan can only handle a max of .5 amps then at any given time one piece of equipment can see that 2 amps. That's not good. So the correct way would be a wire that can handle the amperage of the relay's circuit. So if it's a 30 amp relay then the appropriate wire for the 30 amps then when you split off an individual fuse per fan that is still small enough to protect whatever wire you are downsizing to for the run to the fan. That goes for all situations. I wanted that to be clear. Don't fuse to protect equipment fuse to protect wire.

I always use a 1 up, 1 down rule. Figure the wire size for my max current then get 1 size bigger. I then get a fuse one size smaller than my max draw. Hopefully it will blow first.
Fuses are known for now blowing fast enough. There has been plenty of test showing fuses taking double the alleged current allowance for milliseconds before blowing. Well, there goes your equipment.

Now that I said all that. In my car I would just run one 2 amp fuse for all 4 fans.
 

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Fan direction: I’d suggest mirroring how they work in the PC, suck hot air away from the amp.

But like inside the PC, this will work best if the fan is right up against the amp.
 

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Be careful with the noise level on PC fans. Try to find a balance between DB and CFM.

You want the fans moving air across the heatsink. I would put them both on one end.
 

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Discussion Starter #15
Be careful with the noise level on PC fans. Try to find a balance between DB and CFM.

You want the fans moving air across the heatsink. I would put them both on one end.
I'm thinking of making it where they will sit over top of the amp. I don't think it will be effective putting one on each side of the amp because it's open space. I don't think noise will be an issue since they will be in his trunk.
 

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Have a dmm to check the the relay is engaging and supplying 12V when the radio turns on? The fan is wired correctly to the relay? Is the amp turning on?
 

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Discussion Starter #18
Have a dmm to check the the relay is engaging and supplying 12V when the radio turns on? The fan is wired correctly to the relay? Is the amp turning on?
I'm testing in the shop right now, not in the car. 87 is running to 12v. 85 is going to ground. 86 has a wire going to the remote wire of an Alpine receiver. 30 is going to the red power wire of the fan. The fan's black wire is going to a ground.

When I push "SOURCE" on the head unit to turn it on, or change from tuner to CD, I can hear the relay clicking.
 

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The same ground as the relay? Just making sure.
If you disconnect the remote what happens?
 

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Discussion Starter #20
The same ground as the relay? Just making sure.
If you disconnect the remote what happens?
OK...so I disconnected the wire going to the 30 (remote) and I noticed a little spark and I noticed the fan spin a little. When I connected it back the fan started up and spun. I don't know why it wasn't working until I disconnected and reconnected.

Another interesting thing I just learned is this Alpine has a blue turn on for powered antenna and a blue (with stripe) wire for turn-on. I wondered why the fan would stop when I changed to CD. I remember this being brought up in another thread where someone asked about a turn-on. I said at the time I had never seen a remote wire AND powered antenna wire. Now I have.
 
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