Happy New Year to all

In between watching the Rose Bowel which is really good this year I have been searching the forum for posts on wiring an electric radiator fan.

On my 454 HO conversion in 74 I went with a Derale 14 "single puller 2100 cfm with shroud and control module. I mounted the control module on the driver's side inner fender along with the 25 amp circuit breaker. The Spal Fan advertise that it pulls 16.2 amps for low speed and 22 amps for high speed.

The directions call for the the power source to be connected directly to the battery which for our beloved vettes presents some decision making. The forum has plenty of posts on why that is a good idea on a 43 year-old car and thats how i want to do it - mini starter selonoid is packed

The control module comes with 10 gage wire

Sooooo for you guys that have that have done this does. Does one go up to an 8 gage for the extra length from the battery to the circuit breaker. Any suggestions routing the power source to the battery - through the car underneath. Should the power source be separate from the wiring harness incase of a malfunction and it gets too hot or can it be incorporated so it's nice and clean

Thanks in advance for any replies
Happy New Year

 

I wired mine directly from the alternator

 

THAT is the way to do it, running that voltage drop through a stock or similar harness is just krazy......and will limit the battery from ever getting a full charge.....I can't believe that Spal says to run them off the battery, that is poor engineering decision.....

 

I had mine wired to alt but the fan speed changed with engine rpms. It drove me crazy. I'm no wiring expert so it may have been something missing from my setup. I switched power to battery and fan speed is perfect. I have Spal dual 11s and used the recommended wiring kit. I ran the wire through firewall behind glovebox then under center console to battery.

 

There is are several reasons to wire to the battery-

The battery does more than just start your car- it stabilizes voltage swings and filters the AC ripple from the alternator.

In the Vette- a good connection point would be the starter terminal- as you have a 4 gu wire directly from the battery.

The reason manufacturer's say "the battery"- is so every time the fan(s) start up- which is usually at idle- when the alternator is putting out the least amount of power- a tremendous amount of current required to start up the fans.

So at idle- fans come on-they pull upwards of 60-70A and since the alternator is incapable of that much current at 700RPM- the power has to come from where? The BATTERY - though the small gauge wire in which GM had no idea 40-50 years ago that you would need that amount of current. And it travels several feet under the the hood across the firewall to the starter then to the battery. Sorry- just not a great idea....

The same reason when you jump a car- you would NOT jump off the alternator terminal- try it sometime!!!

Sure- the fans will work of the alternator- but the life of is shortened of both the fans and alternator.

Richard

In my car - have a bunch of stuff I need power for up front - so I ran a 4GU from the starter to the front of the rad support.
Headlights-Headlight Motors-Fans-Horns

DSCN5170 by Richard Hayes, on Flickr


DSCN5169 by Richard Hayes, on Flickr

 

Definately make a dedicated run to the battery. Either put a breaker or fuse on the battery end to protect your wiring in the event of a dead short.
I used the Derale controller and their directions specifically call out not to use the alternator as a power source and would void their warranty due to noise and spikes.

If you look in the picture between the brake master cylinder and alternator is where i mounted mine. And i did go with 8 gauge wire and breaker.

 

I truly appreciate the quick responses as i am off today and wanted to get this wiring done.

Richard 454 In hind sight I wish I would have done what you did. while the eng and tranny were out I ran a new power line and a ground line from the bat to the engine block. Then a ground bus bar in the eng compartment all of my grounds are to this bus bar back to the battery.

Here is a photo. With new body mounts the Hurst 5 speed i put in fit with room to spare.

Darinm and Bloodzone I mounted my control box the same place you guys did and will route the power line the same way. I will also, for extra safety, go up to an 8 gage from the bat to the circuit breaker.

Mrvette I follow and am guided by your posts but i am confused on this one did you mean to say it is poor enginerering to go from the altinator.

Thanks again for the informative responses
Time to get busy

 

8 gauge all the way to the battery just makes no sense when you have the stock 4 gauge coming from the battery to the starter solenoid. In your case, it appears you might even have installed a heavier wire then stock so you're even better off.

To run an electric fan you should be installing a higher capacity alternator and upgrading the charging wire from the alternator to the starter solenoid. So, any possible question about the old stock charging wire from the alternator to the solenoid handling the fan current is nullified once you have properly upgraded.

The biggest problem with a 74 is that it has an ammeter and once you upgrade the charging wire the ammeter doesn't work the same. The best option would be to change the gauge out to a voltmeter.

 

I would think that the easiest place to get 12vdc power for the radiator fan would be from the 'hot' terminal on the starter solenoid. The lug on that terminal is directly from the battery, so extending from there to the electric fans would be both 'logical' and 'available'.

And, using an 8ga. wire to run from there makes good sense to me. The overcost for a few feet of wire can't be all that much; and it just offers more current capacity.

Just as important is the "ground" location for your fan. And I think the place to go for that would be to the right motor mount bolt that receives the electrical ground from the frame. Use 8 ga. wire for that, also.

 

100% agree. One thing you should consider is an in line fuse or breaker, you can find really good used breakers from 20 amp on up at your local salvage yard very cheap or go buy a new one. Marine equipment is good for terminating fuses & breakers.

 

I did not watch the Rose Bowel, but I did wire my electric fan with a 6 gauge wire to the starter lug.

 

Several ways to skin this cat.

I have a 74 also and use the junction box shown. You can also see the thermostat.




I went Junction box > fusible link > relay > fan.

 

I did boost up the charging system with a new 140 amp alternator and an 8 gage wire from the starter to the junction box.

I have headers and a mini starter and it is really congested in there especially with the heaveir 12v pos cable i ran from the battery.

I ran an 8 gage from the battery to the 25 amp circuit breaker which is mounted on the driver's side fender. It was a piece of cake and is real accessible.

I will advise on how this works

Next is the A/C system

Thanks for the responses

 

Here's how I did mine. It's still a work in progress so we'll see how it stands up to wear and tear.

• 2/0 cable from battery to 'post'. This is junction for power distribution in engine area. I also use it as jumper terminal if needed. In addition to the battery wire are 4 connections:
• 6 awg wire to 6 fuse panel. Each fan gets its own fuse.
• 4 awg wire from alternator
• 2 awg wire to ford style solenoid
• and stock power wire that was previously connected to main power lug on starter.

The fan power goes from this fuse box, a 10 awg for each fan, to circuit break, relay, fan.

 

Note, the fuse should go as close to the power source as possible not at the fan, if that wire gets damaged between the fuse and power source you will have a BBQ.

 

Here you go- this is neat solution-






Marine buss bars-

DSCN5091 by Richard Hayes, on Flickr

 

You are right I will change that

 

Richard 454 I'm thinking I like your bus bars / junction boxes better then mine. Mine are the Ron Frances

 

Thanks-

Here's another option- next time you are at the junkyard- mid 90's BMW's (5 & 7 series) used a really neat through firewall terminal block-these are almost free!!!



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