Electrical Engineer question

[triracer67]

I recently installed a 16” Derale 2-speed electric fan on my Bronco, it’s switch wired to dash with 12 gauge wire, starting at battery positive. It works good, but, I want to make sure I’m getting max output, and it’s awfully quiet. I did wire per instructions. Question is, does the 12 gauge wire limit the power I’m sending to fan?

 

[CA Monkey]

it doesn't limit the power but it will overheat and fail. 12 gauge wiring is usually good for a max of 20 amps. the derale 16" pulls close to 24. I wouldn't be worried about it if you went through a relay kept in the engine compartment but hardwiring it to a switch on the dash a wire thats being overdrawn is likely to cause a problem.

I would advice against leaving it that way.

 

[Broncobowsher]

Measure the voltage at the fan and compare to at the battery (also with the fan running). The difference is the voltage drop. There will be voltage drop, you don't have superconductor wiring. Now the question is how much. It isn't just the wire, it is the switch and every junction and even the grounds to the fan.

 

[kylakekevin]

It also depends on the type of wire and insulation on said wire to come up with the rating for it. A fine strand wire is rated higher than a course strand wire. Insulation is another can of worms. My self I prefer to have a solenoid under the hood for all aftermarket devices.

 

[68Broncoz]

I would run the fan thru a relay and use wire rated for the amps from the bat thru the relay to the fan. I would also add a fuse in the relay circuit as well

 

[Justafordguy]

I agree, I would use a relay by the battery and use 10ga wire and fuse it if it pulls 24 amps. Then just use a smaller wire from your switch to activate the relay. That's how I have my trans cooler fan and A/C condenser fan.

 

[73azbronco]

You should be using a relay.

 

[Timmy390]

Do you have the fan wired to a single switch? Flip a switch to turn it on/off?

I'm running the 17 inch Derale 2-speed electric fan WH sells and it is suggested per the instructions to run a fan controller.

I know in the instructions it states for the fan to go into high speed, it has to already be in slow speed. So the fan has to be running in low speed then kicked into high speed. This is more than likely due to the huge amps it pulls at startup.

I guess I took a long winded way of saying if you only have a single position switch on/off hooked up to the fan, it's more than likely NOT going into high speed

As stated, use a relay for sure. I built my own controller with help from EFIGuy. My ECU has fan control built in.

Tim

 

[Skiddy]

yes use a relay or two. just re-did mine last weekend. I would go through switches about every year or so%) this is the Taurus fan and does pull a lot of amps

 

[Steve83]

Question is, does the 12 gauge wire limit the power I’m sending to fan?

Measure voltage across the battery POSTS with the engine & fan running (alternator working); and then across the motor terminals (as close to the motor as you can get) with the fan running. Post each reading.

The more connections & contacts (switch, relay, etc.) in the circuit, the lower the fan voltage will be, and the more power will be wasted.