Electrical advice?

Post by **Merlin** » Thu Apr 24, 2014 9:52 am

I am going to wire in my new ventilation fan for my track car. It only draws 12V & 2.5amp. Is it worth powering it via a relay or will that amount of power be OK through a switch?

Post by **4thgenphil** » Thu Apr 24, 2014 10:24 am

Is the existing fan on a relay and if ao could you splice it into that circuit?

Also is it a 3 or 4 incher?

Post by **Merlin** » Thu Apr 24, 2014 10:36 am

Yeah the OEM blower would be on a relay but tapping into the wiring for it may get messy and complicated. But I will investigate anyway.

I am using a 3" fan (Flow Rate 130CFM / 3690L/MIN). Fingers crossed it will blow a lot. I may adapt it to blow at my face when not needed to clear the screen. Last Sunday I was sweating buckets

This is a potential stop gap until I want/get a T7Design mini heater matrix (for which I have already installed the fixings for).

Post by **Merlin** » Thu Apr 24, 2014 12:21 pm

The switch I am using says it is 20amp. Does that mean that it can handle up to 20amps without issue? So it would be safe to run my main power through the switch?

Post by **indigolemon** » Thu Apr 24, 2014 12:30 pm

Yep - that would be my understanding. In-line fuse, then switch, then fan.

Post by **Merlin** » Thu Apr 24, 2014 12:37 pm

Awesome sauce. That makes thing much easier and requires less wiring

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Thu Apr 24, 2014 2:32 pm

Yep, there's no need to run that through a relay.

The standard one is only on a relay so it switches off with the ignition.

When the ignition is on, the blower motor has a permanent live feed to it blower and is switched on by closing the circuit to earth. For the lower speeds, this is through resistors (to drop the voltage and make the fan run slower) but when in high speed it's dropped straight to earth through the fan control switch, so the full current goes through the switch.

2.5 amps is not a lot of current...

Post by **Merlin** » Thu Apr 24, 2014 2:36 pm

Thanks for the confirmation.

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Fri Apr 25, 2014 8:09 am