12v fan wiring question

[A930Rocket]

What size wire and fuse would I use for a 12 V 80 W fan?

Looking online, the formula is 80/12=6.66 amp.

Would I use a 5 or 7.5 amp fuse or ?

What size wire?

[john70t]

Length and fan motor draw has a lot to do with it. When modified.

Look at the factory wiring diagram and the fuse box.
Compare the existing wire.
Replace with same or better.

You can replace that with 10 gauge a half inch thick. But as long as the fuse is still the weakest link then it's all good.

[pwd72s]

You definitely want to go hell for stout on the wiring to the fan itself. Depending on the car, of course...but maybe add a relay? Here's a thread on a Mustang board I visit...sometimes even factory engineers design wrong. In ford's case, the wiring too small to handle the surge in power demand of the fan coming on. Read on:

https://www.imboc.com/threads/burnt-fuse-block-low-speed-fan.378530/

[A930Rocket]

This is for a small aftermarket 6” fan for my oil cooler. For now, I’m going to wire it with a switch, but may set up a relay later.

The positive wire with a fuse is about 4’. The negative wire run to the interior switch is about 6’.

6'' Inch Small Slim Push Pull Electric Cooling Fan 650CFM Radiator Oil Cooler Mount Kit Universal Black

https://a.co/d/02Wn0XE

This same company has a 12V 80W 10 inch fan with a relay kit, includes a 30 amp fuse. Not to say they are right, but is a 30 amp fuse right?

[908/930]

Likely want to go 10GA wire, they are suggesting 30A fuse. The fuse is to protect the wire, the actual amperage is probably lower with your alternator likely producing 14V. You would want to make sure your relay or switch is rated for 30A, likely easier to use a relay, then the switch rating can be lower and use smaller wires from the relay to the switch.

The 30A is likely whats required for motor inrush current.

EDIT, You should be ok using 12GA wire, your distance is pretty short so low voltage drop.

[pwd72s]

Why not? Gotta be a reason they suggested a big fuse. Fans pull a lot of amps when they first come on...

[Zeke]

I was going to say 12 ga. but do it well using quality connections. The ends are what gets hot.
There is discussion as to whether any solder should be used under connections. I think the consensus is no. Solder is FOR connections when called for, not used together with a compression type.

Actually, I did not know that.

[A930Rocket]

I use an expensive crimping tool that has shrink tubing built into the connectors. Crimp and shrimp. Much easier than soldering.

I ordered some 12 gauge wire on Amazon, that will be here tomorrow.

[911_Dude]

No solder for wires used in vibration environments like cars, boats, etc. WIth solder you will likely get a fatigue cracked wire where the solder ends. With a proper crimp, there is no advantage to solder in both strength or conductivity. Same with using single strand wire. You always want to use multi-strand wires for mobile applications to avoid fatigue cracking.

[asphaltgambler]

+ today's solder is not the solder of old. Higher resistance across that connection. The mercury that was used in the mix was eliminated some years ago.

[A930Rocket]

Replaced the wire originally used for the ground and the longer run, with 12 gauge wire. I installed a 10 amp fuse for now. The fan works, so when I go to the track in a couple weeks, it’ll be interesting to see what temps I get.

Edit: The oil cooler itself isn’t that big, because I did not want to block too much air flow to the radiator. Hopefully, it’s doing something with the fan attached now.

Edit 2: Hopefully this weekend, I can install the thermostat to the oil cooler.