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Main 12V Feed Wiring

Practical Motorsport Wiring - Club Level

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Discussion and questions related to the course Practical Motorsport Wiring - Club Level

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Are there are any pros/cons (recommendations) with the following options for wiring the main feed to the Relay Fuse Box?

Option 1:

Battery -> Cutoff Switch -> Bulkhead |-> Starter

_______________________Bulkhead |-> Alternator

_______________________Bulkhead |-> Relay Fuse Box -> ECU

Option 2:

Battery -> Cutoff Switch -> Bulkhead |-> Starter

_______________________Bulkhead |-> Alternator

Battery -> Cutoff Switch -> Relay Fuse Box -> ECU

i.e Option 1 has single main 12v feed to bulkhead then splits off to 3 items, where as Option 2 runs a separate feed from cutoff switch to Relay Fuse Box.

Distances:

Battery -> Cutoff Switch = 1m

Cutoff Switch -> Bulkhead = 1m

Cutoff Switch -> Relay Fuse Box = 1m

You want #1.

Remember that under normal operating conditions, the alternator is the only true power source. The battery is a net consumer, except during starting.

If you do option #2, then the length from the Alternator to the fusebox would be double, and hence double the voltage drop.

I'm assuming you'll have a pass-through post at the bulkhead. There's no harm in having 3 lugs on it.

That's a good point I hadn't actually considered, I was thinking from battery forward, but your completely right about the alternator! Thanks for the advice :)