Relays, fuses and other electrickery for my fan setup???





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  1. #1
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    Default Relays, fuses and other electrickery for my fan setup???

    I'm busy improving my V8's airflow issues by fitting 4 fans to the radiator.
    The fans are mounted and perform very well by just roughly connecting them directly to the battery.

    Now I need to wire it all up to work the right way.

    I'm not very good with automotive electrickery, so I please need some help. I want to do this myself, because local auto elecs just dissapoint me

    Two of the fans are 90Watt each and I think the 2 big ones are 200Watt each, that's 580 Watts I need to drive.

    I've got a thermal switch, but I know I cannot use that directly and need to incorporate a relay. I also need a switch to cut all power to the fans for water crossings.

    My questions are as follows:

    What size fuse do I need?
    What size cable do I need?
    What size relay do I need?
    How do I wire up the relay, switch, fuse and thermal switch into the system?
    A simple wiring diagram will help a lot

  2. #2
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    Hi Zantus

    You have some serious blowing power there.

    The combined load would be in the range of about 49A so I would suggest you split the circuit on to 3 relays with the two big fans on their own circuit and the smaller ones together.

    The big ones will draw about 16A ea so I would opt for 4mm wire that could safely handle 30A and a standard Hella 30A 4pin relay that is also standard stock at any spares outlet. Each circuit should have its own 30A fuse to protect the cable.

    The relays get power from the battery through it's own fuse and passes that on to the fans if switched on. The relays are switched on by the master switch and the thermal switch. For the fans to come on both master and thermal switch have to be on.

    Excuse my draughting as it was done on the quick.

    Shout if you need more

    Henk
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    Last edited by hbannink; 2008/07/22 at 01:06 AM.
    Henk
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  3. #3
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    Stem, got to the same

  4. #4
    4ePajero Guest

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    Barto,

    The attached diagram is for a fog light, but it is similar to one of your three circuits.

    It does however show the pin numbers on the relay, which the other diagram does not have.
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  6. #6
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    I got the relays, fuse holders and a very nice 3 way switch....I'm going to make it that I either have fans off, fans on thermo switch, or fans permanently on.

    I suppose I don't need as heavy cabling running to the thermo switch and the toggle switch, and only the heavy stuff from fan to relay and battery to relay?

  7. #7
    4ePajero Guest

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    Quote Originally Posted by Zantus View Post
    I suppose I don't need as heavy cabling running to the thermo switch and the toggle switch, and only the heavy stuff from fan to relay and battery to relay?
    Yes

  8. #8
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    I would use an arrangement where you could switch off one or two fans when not needed, for when travelling at high speed on an open road, for example. To draw 50A from an electrical system continuously is hectic, to say the least! But you should wire the fans through a by-pass thermo switch in case the temperature does creep up.

    I would also fit some sort of safeguard onto the Master switch to remind you to switch the fans on again after a water crossing. Use an annoying buzzer, a bright flashing LED/Light or something similar. Give each fan its own fuse.

    I was going to suggest fitting a 4Y engine and get rid of all the baggage, but I don't think you wanted to hear that...


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  9. #9
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    The fans don't come on at anything above crawling speed in traffic and then when it does come on, I need all the airflow I can get, so I don't want to switch off any of the fans.

  10. #10
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    Quote Originally Posted by Zantus View Post
    The fans don't come on at anything above crawling speed in traffic and then when it does come on...........
    .........Be ready to hit the brakes with that amount of cooling I doubt that it is going to fire up for very long.
    for your control circuit you can use thin wire as it only has to supply the relays and their current drain is minute.

    Thanks "oom" 4E for the life of me I can not remember the coding on the relays and have to sit with a multimeter every time I connect one.
    Henk
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