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    Rally car wiring/electrical system questions

    Regarding to a proper wiring loom ( electrical system );

    - should I rather use a big amper main fuse before the relay-fuse box OR design the system only with the individual relays/fuses with the each circuit ( electric fan, fuel pump/s, lights, spots etc ) ?

    - if answer is “yes” to above question, then what should be the “ amperage “ of the main fuse ?

    - do you happen to have the necessary “ amperage “ for the each possible circuit in a rally car loom ? ( I mean the amperage of the each individual fuse for the related circuit)

    - do you happen to have a rally car wiring diagram ?

    Regards

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    Re: Rally car wiring/electrical system questions

    I don't use a main fuse, just route two slightly smaller main cables from battery + side to emergency switch.
    From other side of e-switch smaller wires (1.5 mm2 or 2.5 mm2) to each individual circuit.
    Use resetable fuses some are 8 Amps, lots are 16 Amps, some are 25 Amps (like spotlights).

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by Miniliteman View Post
    I don't use a main fuse, just route two slightly smaller main cables from battery + side to emergency switch.
    From other side of e-switch smaller wires (1.5 mm2 or 2.5 mm2) to each individual circuit.
    Use resetable fuses some are 8 Amps, lots are 16 Amps, some are 25 Amps (like spotlights).
    Hi Leon,

    Do you happen to have a basic diagram ?
    Each circuit should have an individual relay and an individual correctly rated fuse, shouldn’t it ?
    Fan, fuel pumps, spots should always have relays, but what else do you think should have relays in a typical Escort rally wiring ?

    Regards

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    Re: Rally car wiring/electrical system questions

    Where possible, protect all wiring with suitably sized fuses.

    Fuses are not to protect what is connected at the end of the wires...but to protect the wiring install itself in case of a problem or short, as that's what will cause the fire.

    So fuses ( or breakers might be handier in a rally car ) where appropriate and as close to main power sources as possible.

    And yes, in many ways the more fuses/circuits the better, but that can add wiring and/or complication, so you need to decide what works best for you.

    Of course one circuit per item can also make fault finding on the road easier, or help enable a vehicle to continue a rally if one circuit does have a problem.
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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by hawk1903 View Post
    Hi Leon,

    Do you happen to have a basic diagram ?
    Each circuit should have an individual relay and an individual correctly rated fuse, shouldn’t it ?
    Fan, fuel pumps, spots should always have relays, but what else do you think should have relays in a typical Escort rally wiring ?

    Regards
    Don't have a readable wiring diagram, just some drawings rest is in my head.
    But it is not rocket science.
    From switched side of emergency switch route a wire towards every fuse then to the relay or directly to an appliance.
    Std blower, ignition, fuel pumps (Facet), horn, rear lights don't need a relay.
    Spotlights, heated rear window, radiator-fan do, and the wipers use the intermittant-relay.
    For an Escort I always use a std loom to start with as it has most of the wiring plus all the connectors for the stalks. If needed I replace worn/damaged pins as I have most of these as a spare.
    Made a loom for a Sierra Cup racer years ago I started that from scratch as only the basic stuff was needed.
    That car still has the fastest lap for a Sierra Cup car at Zandvoort! Because of the lightweight loom ofcourse ...

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    Re: Rally car wiring/electrical system questions

    Thank you very much. Fully understood. Usually my colleague takes care of the wiring but recently we were not quite sure if we were doing it correctly. On one of rally cars we had a 60A main fuse prior to fuse/relay box which broke without any particular reason. None of the other fuses which are inline to the various appliances did not brake but just the main fuse coming from the master switch ( emergency switch ) to the fuse panel. This was not a new harness or anything, actually it has been there since ages. It may well be the case that it eventually become little loose then burnt itself. I don't know.
    Now, we are planning to remove the main fuse and have the system without it.

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    Re: Rally car wiring/electrical system questions

    i certainly would avoid having a main fuse, two reasons a it needs to be big enough that it will handle large current loads, but that by default means most circuits could overload and melt before it would blow, but secondly even a minor fault with it, might be a connection issue or even vibration damage could wipe out all the cars electrics

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by Miniliteman View Post
    Don't have a readable wiring diagram, just some drawings rest is in my head.
    But it is not rocket science.
    From switched side of emergency switch route a wire towards every fuse then to the relay or directly to an appliance.
    Std blower, ignition, fuel pumps (Facet), horn, rear lights don't need a relay.
    Spotlights, heated rear window, radiator-fan do, and the wipers use the intermittant-relay.
    For an Escort I always use a std loom to start with as it has most of the wiring plus all the connectors for the stalks. If needed I replace worn/damaged pins as I have most of these as a spare.
    Made a loom for a Sierra Cup racer years ago I started that from scratch as only the basic stuff was needed.
    That car still has the fastest lap for a Sierra Cup car at Zandvoort! Because of the lightweight loom ofcourse ...
    Thank you very much, Leon.
    I understand all your points. However, we always used relays on the Facets. Is there certain amperage level that requires relays ? ( just to understand better )
    As I mentioned above, my colleague works on the wiring and he usually starts with Escort,s original loom as well. However, he has also wired some rally cars from scratch but adding the necessary connectors for the stalks etc. So, it became a kind of hybrid system.

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by Graham View Post
    i certainly would avoid having a main fuse, two reasons a it needs to be big enough that it will handle large current loads, but that by default means most circuits could overload and melt before it would blow, but secondly even a minor fault with it, might be a connection issue or even vibration damage could wipe out all the cars electrics
    Hi Graham,
    We have just had that issue at the last sector of the last stage of a 2 day long stage rally and by the time the driver found the burnt/melted main fuse it was too late.

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    Re: Rally car wiring/electrical system questions

    Use a battery isolator, a fuse is a bad idea.

    Cartek do an electronic one that isolates the battery ground, expensive, but far better than an electrical fire that you can't put out...

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by hawk1903 View Post
    However, we always used relays on the Facets. Is there certain amperage level that requires relays ? ( just to understand better )
    A relay is used when the current for the contacts in a normal switch are too high and/or switching a load off gives a high voltage spike which could damage the contacts inside a switch.
    For anything not exceeding 6-8 Amps I don't use a relay; that includes Facet pumps, ignition, blower motor, small lights, Terratrip, lambda-heater-element, dash etc.
    Use a proper tool to crimp fastons and similar connectors. Do not solder terminals unless the max current is less than 100 mAmps (sensors).
    If someone suggests that you should use quick-release battery terminals send him away, fire him, disown him, etc as these are major source of electrical troubles.

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    Re: Rally car wiring/electrical system questions

    Watts divided by voltage = amps

    50w light would be 4.16 amps

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by Duffer View Post
    Use a battery isolator, a fuse is a bad idea.

    Cartek do an electronic one that isolates the battery ground, expensive, but far better than an electrical fire that you can't put out...
    Thank you very much. We always had the idea of switching to an electronic battery isolator but never happened. We are now seriously reconsidering the idea.

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    Re: Rally car wiring/electrical system questions

    Quote Originally Posted by Miniliteman View Post
    A relay is used when the current for the contacts in a normal switch are too high and/or switching a load off gives a high voltage spike which could damage the contacts inside a switch.
    For anything not exceeding 6-8 Amps I don't use a relay; that includes Facet pumps, ignition, blower motor, small lights, Terratrip, lambda-heater-element, dash etc.
    Use a proper tool to crimp fastons and similar connectors. Do not solder terminals unless the max current is less than 100 mAmps (sensors).
    If someone suggests that you should use quick-release battery terminals send him away, fire him, disown him, etc as these are major source of electrical troubles.
    Thank you very much, Leon. We only had one car with the main fuse before the fuse box and that one broke. We will remove it since the rest of the system is designed well, I could even say it is an overkill with relays for Facets etc.

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