UKCRC Forum

Technical => Electrics => Topic started by: RickW on Jul 06, 2024, 10:48 AM

Title: Wiring twin fans - advice
Post by: RickW on Jul 06, 2024, 10:48 AM
Hi all, hoping someone can guide me if what I am doing is safe and correct:

I want to add twin cooling fan (both 80w) to my radiator, but not connected through my ignition and have a toggle switch control both fans at the same time.

Wiring for each Relay as follow:

PIN 30 - Live feed from my Isolator Switch on the Battery using 10 gauge wire
PIN 86 - Live feed from the same point as above using 16 gauge wire
Pin 85 - Connected to a single toggle switch (from both relays)
Pin 87 - Connected to FAN ( Fan to be earth ) - 16 gauge wire

FUES Do I :

1 - Put a FUSE between the Battery and Relays - Using 40 amp fuse that will feed both Relays.
or
2 - Put 15 Amp between the Relay and Fan - Fuse for each fan.
or
BOTH


Many thanks in anticipation for your helpful advice and comments to the above.

Rick..
Title: Re: Wiring twin fans - advice
Post by: KevinW on Jul 07, 2024, 07:05 PM

Just be aware that if you are using longer runs, then there will be a larger voltage drop across the wire run, which you really want to avoid.

Further details here:
https://www.12voltplanet.co.uk/cable-sizing-selection.html

Title: Re: Wiring twin fans - advice
Post by: Chris on Jul 07, 2024, 08:52 PM
Also would advise that you  use the descent large spade connectors that go to the relays .
My preference would be to solder these as opposed to crimps, that's what I have done for my twin fan set up.
These fans are very current thirsty and will find out any poor connection !
Chris.
Title: Re: Wiring twin fans - advice
Post by: RickW on Jul 07, 2024, 09:35 PM
Many thanks KevinW and Chris, appreciate the replies, link and advise.

RickW
Title: Re: Wiring twin fans - advice
Post by: JON1D on Jul 07, 2024, 11:17 PM
You can look at a Davies Craig Fan Switch / Digital Thermatic EWP - Cooling System

https://www.youtube.com/watch?v=vWHkv5AaC_0

A neat solution. I would go with a thermostat installed into the radiator.
 
Title: Re: Wiring twin fans - advice
Post by: RickW on Jul 08, 2024, 08:04 PM
Thanks JON1D great idea and simpler for me to do as well..
Title: Re: Wiring twin fans - advice
Post by: KevinW on Jul 09, 2024, 07:42 AM
Quote from: JON1D on Jul 07, 2024, 11:17 PMYou can look at a Davies Craig Fan Switch / Digital Thermatic EWP - Cooling System

https://www.youtube.com/watch?v=vWHkv5AaC_0

A neat solution. I would go with a thermostat installed into the radiator.
 

I have one of these installed, although the external sensor is a bit of a PITA. I'd go with Jon's suggestion.
Title: Re: Wiring twin fans - advice
Post by: RickW on Jul 09, 2024, 08:12 AM
Thank you KevinW and like the whole idea and setup.
Title: Re: Wiring twin fans - advice
Post by: Waitey on Aug 08, 2024, 10:22 AM
Some nice PWM controllers available now too for not much money.

Just make sure the sensor is in a sensible place. I've seen a lot of warped ali heads due to daft sensor placement.
Title: Re: Wiring twin fans - advice
Post by: KevinW on Aug 10, 2024, 10:47 AM
Quote from: Waitey on Aug 08, 2024, 10:22 AMSome nice PWM controllers available now too for not much money.

Just make sure the sensor is in a sensible place. I've seen a lot of warped ali heads due to daft sensor placement.
Sensor switching on too late or ...?