Factory Five Racing Forum banner
1 - 6 of 6 Posts

·
Registered
Joined
·
1,581 Posts
Discussion Starter · #1 ·
Does it make any difference where the fan relay is located with respect to the fan its self? Or another way to ask the question, does the relay need to be near the fan?

I plan to have a 10 gauge wire from the battery to a 30 amp breaker and then to the relay and then to the fan.

Battery ----- 30amp breaker ----- relay ----- fan.
 

·
Official OLD GUY
Joined
·
3,877 Posts
Close is good

The closer to the device being powered, the better the voltage at the power terminals.
Relays are placed in a circuit so that the smaller devices (activation switches, thermostats, sensors,etc.) don't take the full amperage of the device being powered.

It only take about 200Ma to pull in a relay, so being far away from the activation switch doesn't really matter that much. The closer the device is to the power source (battery / alternator) the lower the voltage drop across copper wire will be . . . so your device gets full voltage and runs as efficiently as possible.

FWIW, I have my fan (headlights & horns) relay(s) mounted on the upright on both sides of the front "X" brace . . . within a foot of the device being powered. Wire to the relay coil(s) from the dash toggles is 18Ga. Wire from the starter solenoid to the relays is 10Ga / 10Ga & 12Ga respectively.

HTH

Doc :beerchug:
 

·
Registered
Joined
·
1,581 Posts
Discussion Starter · #3 ·
I understand that the shorter the run between the power source (battery) and the device being powered (fan), the better.

What is the benefit, if any, of having the relay close to the powered device (fan) verses close to the power source (battery).
 

·
Premium Member
Joined
·
18,253 Posts
I mounted all my relays under the dash, and very close to the power source. I like those components to be protected from the elements.

Also, the only time that circuit is live is when the relay is switched on. The only part of the wire that has power all the time is the 6" of wire between the relay and power junction. For some reason, that makes me feel better.
 

·
Official OLD GUY
Joined
·
3,877 Posts
either / or

{quote} " What is the benefit, if any, of having the relay close to the powered device (fan) verses close to the power source (battery). "

Bob has the right idea when he states that the only thing "live" is the short wire from the power source and the #30 terminal of the relay. This would constitute a "safer" situation, less exposed wire that is energized.

The opposing thought on this is; keeping as much "high amperage" components out from under your dash. FWIW, I'd rather have an electrical short in the engine compartment then in the cockpit hidden up under something I can't get to . . . hence, all my high amperage relays are mounted outside of the cockpit.

To answer your question, it would not make any difference if the relay is close to the fan or close to the battery, the optimal placing is more for wire routing convenience and ease of access when the need comes about. Also, consider length of the wire run: Battery power to relay under dash, back out from under dash to device as opposed to battery to relay to device . . . short runs make for less voltage drop.

HTH

Doc
 

·
Registered
Joined
·
1,581 Posts
Discussion Starter · #6 ·
Thanks for the suggestions. I plan to mount the relay in a protected area on the firewall near the starter (battery power source). I'll run a fused #10 wire from the battery to the relay and then another #10 from the relay to the fan. Like this:

 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top