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  • Power fans off of car?

    Ok here is what I have setup right now. I'm already fairly certain i'm going to need a dc to dc converter for this to work best, but I'd like the advice from someone else to ensure this.

    I have an amp and an enclosure I have made for it that will house my pc components also. I do not have the components for the pc yet because I am contemplating on whether I want to do it or not because of the screen being read in sunlight. Not sure I want to shell out $700-800 for a transflective. Anyways, I don't have a dc to dc converter and I was wondering if the best way to power 4-60mm and 2-80mm fans would be to use a dc-dc or if there is a better easier/cheaper solution for the time being. I had asked someone in person and they said the 12v in the car should do just fine, but that fluctuates in a car from 11.5-14.5v or so and that would be running my fans at an unnecessary speed and most likely cause them to have a shorter life span and probably make a lot of unneeded noise also.

    What are some thoughts on this?

  • #2
    I agree with your assessment of the issues. The shortened life probably won't be significant. I doubt the extra noise will be significant either, but that is pretty subjective so you might find you don't like it.

    If you can live with the reduced air movement, a higher voltage fan (24v) would run slower and last longer, but I don't know about availability.

    You won't need a very good dc-dc converter (tight regulation, low ripple output) to run fans so an inexpensive one would do and give some control over the speed if you get one with a bit of adjustment.

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    • #3
      A low-dropout regulator would probably do it...
      although running your fans at 14v probably wont do them any noticeable damage.
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      • #4
        Just tap into your 12V that is going to your PS for your future PC. Get a distribution block and just hook up your fans to it. Just make sure its sealed off so you don't get random wires touching it.

        I wouldn't worry about damaging your fans, unless they're extremely high quality fans. They'll probably last longer than your car will.
        Love

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        • #5
          If these are standard PC fans, then there will be a couple of fan connectors on the motherboard.

          See the connector on the left in this image, which is 12v regulated, and sometimes controlled by the motherboards BIOS depending on heat:

          [media]http://www.elma.it/IMAGES/fantt/4in4a.jpg[/media]

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          • #6
            I have 4 fans connected directly into the 12v line. When I turn on the car, they turn on right away. These cool the amps and other devices. The other 4 are connected to the PSU, they cool the case and the PC, they dont turn on until the PC powers up. I notice that the fans directly from the 12v line seem to spin faster then the ones on the PSU.
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            • #7
              yeah... I have some vantec stealth silence fans double bearings. They aren't really cheap fans but aren't extremely expensive. I think I may purchase the M2-ATX for my possible future carputer and then just splice into one of the 12v lines on it that would go to the mobo of the pc (don't have a mobo) I think this is the best solution. What does you guys think? Is the M2-ATX a good solution for car pc applications or would you recommend something else? Thanks

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              • #8
                If you're planning on powering all those fans as well as your PC, you might want to be careful not to overload the M2. It depends on the power requirement of the PC itself. Personally, something like a fan won't be harmed by the relatively small fluctuation in voltage that a car would see. I would run them right off of an IGN source. Again, just make sure the source has enough power. I would use my 12v outlet, because it can handle 10 amps and is fused just in case.
                I remember making many of my Tyco R/C cars go faster by making the motor use higher voltage. It made more noise because of the higher speed, but that's it.
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                • #9
                  yeah... I think that the 160w m2 ought to be enough. I'm getting a kino board with core 2 duo, 2 gig ram, 120gb hdd 7200 rmp, obdII, gps, tuner, and a few other things. I have heard that it will be enough for this but I have not gone through and calculated it. I think I may just see what the fans do when the car is on and hooked up the the cig voltage. I don't have anything else running on it so it'll be fine I think. I'll have to check the amp rating on the fans, but I believe it is only a 1/2A at most for each and there are only six of them.

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                  • #10
                    6 fans, 1/2 A each = 3A. 3A * 12V = 36 watts.

                    Trust me, that makes a difference.

                    Your M2 is capable of 160 watts every here and there, with optimal cooling and solid line loads (no fluctuations). You wouldn't want to put more than say... 140 watts on it max. With those fans, you have 100 watts left. With a CPU (45 watts if it's low power) and a motherboard (25-30 watts with onboard sound)... well, add the harddrive and the GPS and you're done.

                    Careful...
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                    • #11
                      Originally posted by colin View Post
                      Your M2 is capable of 160 watts every here and there, with optimal cooling and solid line loads (no fluctuations). You wouldn't want to put more than say... 140 watts on it max. With those fans, you have 100 watts left. With a CPU (45 watts if it's low power) and a motherboard (25-30 watts with onboard sound)... well, add the harddrive and the GPS and you're done.

                      Careful...
                      It depends on what mobo he's getting, i have the new intel mini-itx with the atom and the whole package together only consumes 40W. If he is getting an ATX then yes there would be concern. Most of the dc-dc PSU's are meant for mini-ITX but some of the nicer ones could easily power an ATX mobo.

                      As for powering the fans off the ignition, i don't think (emphasis on 'think') the 12v ignition would be enough to power your fans. It's a very low amp line, i believe is in the milliamps. The only real purpose of the ignition line is that it tells devices when the car is on, so its more of a data line than a power line.
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                      • #12
                        I don't mean the IGN line, I was more refering to an IGN source. My cig lighters are both switched sources and together they can handle 10 amps.
                        03 Accord Sedan CarPC

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                        • #13
                          From what i understand Fans dont take that much amps. i think i read that its like .08 amps and I may have the numbers transposed, but even so, that will not bog down the PSU at all.
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                          • #14
                            Originally posted by HiJackZX1 View Post
                            From what i understand Fans dont take that much amps. i think i read that its like .08 amps and I may have the numbers transposed, but even so, that will not bog down the PSU at all.
                            Originally posted by colin View Post
                            6 fans, 1/2 A each = 3A. 3A * 12V = 36 watts.

                            Trust me, that makes a difference.
                            So Colin presumes half an amp per fan, and you say "oh no, 0.8A per fan." That's an even bigger draw - 57.6W in total. So even if you're using an Opus 150W, then that's a third of your available power gone, and from the 12V rail too.

                            Your best option is to take a new line from your battery for your fans, fuse it, and put a relay in that is triggered by the IGN line or by the PSU itself. That way the fans come on as soon as the key is turned, and the PSU doesn't see the draw. You could even put in a little voltage regulator like this circuit here.

                            What do you need 6 fans for anyway? Are you planning to run some massively intensive gaming rig off your car? If so, is your alternator up to it?
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                            • #15
                              Originally posted by Grrrmachine View Post
                              So Colin presumes half an amp per fan, and you say "oh no, 0.8A per fan."
                              Check your decimal place. He said .08 Amps.

                              I just checked a couple of fans online and the 80mm ones I looked at ranged from .12 to .23 Amps.

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