Real quick question: Would you consider it sufficient to pull a hot wire from the hot side of the starter solenoid and use as a distribution point for my Taurus fan that will pull 40+ amps?

omitting any discussion about what's going on down the line in terms of circuitry, I am aware of all consequences when running this "notorious" fan.

Thanks everyone.

 

That's probably the best place you'll find to connect high amp draw accessories. Just be sure to fuse the circuit, I prefer to use automatic reset circuit breakers.

 

Why not use the Taurus relay? Yes the starter relay can easily handle the fan current, but the relay coil may not be designed for extended duty.

 

Electrically it is the same as the battery terminal. The only other high-current device on that terminal is the starter so there probably isn't much chance of having them both running at the same time. If you run it that way then watch what happens when the fan engages...if your lights dim then you know you are more than likely in need of a heavier battery cable.

 

They also sell battery cables that have a heavy secondary wire for loads like that, direct from the battery terminal.
Wrong battery terminal but you get the idea

 

Yes, I really like the thought of a circuit breaker vs a normal fuse. Definitely in the plan.

I am going to use a popular Volvo fan relay, this is a very typical setup. Incidentally, I was actually wrong, the Taurus fan I bought won't fit as well as a Volvo fan, so I'll be using the Volvo fan and relay. They should pull similar amounts of amperage.

I'm a little confused by what you stated, relay coil? Do you mean the internal parts that are connected to the physical stud I'll be using?

What gauge wire should I use? 2? 0? All battery and chassis grounding cables will be replaced before truck is operating back on the road. Might as well get the next size up just in case.


Thanks again everyone.






EDIT: My truck has a cigar lighter but it has never worked and the wire goes somewhere I don't know. What is a safe place to get voltage from? Should I use a circuit brake or a fuse? What amperage?
EDIT: EDIT: http://www.fordification.com/tech/wi...odels81-85.jpg

This diagram shows the basic setup. Need a 15 amp fuse for cigar lighter, and I think I will install a 2 amp fuse for the illumination for my aftermarket gauges and wire the lighters light into that.

 

Yes. Tapping power from the battery side of the starter relay is a common practice, mostly because tapping at the battery post on older vehicles was impractical. There is a wide variety of 12 volt circuit breakers available to suit your needs.

http://www.wiringproducts.com/bussma...rcuit-breakers

 

Obviously you need a relay but you also need a circuit breaker or fuse that would handle the load. Here is where I mounted a circuit breaker panel to protect the engine compartment (headlights, fan, electric choke, automatic transmission, etc.).





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Bolting additional loads at the starter relay post is no different than connecting them directly to the battery clamp, provided the battery cable itself is a quality item. The stud on the relay is effectively just a fastener. Regarding starting the engine while other loads are energized... vehicles were simpler then and there really wasn't much in the way of chassis loads. Headlights, blower motor and wipers basically might be the only items on during the starting process and most people were smart enough to turn them off before attempting to start the engine. Today's vehicles with so many possible additional loads utilize a more complex ignition switch that disrupts power to those additional loads when the key is turned to the start position basically leaving the ignition and fuel pump as the primary concerns (anti-theft, and a few other items may be included in that position.) Cars from the '70's & '80s sometimes had electric carburetor choke heating coils that were powered from the alternator stator thereby eliminating two issues - the power drain during start-up and not heating the choke coil until the engine was actually running. One could employ a relay(s) that provides a normally closed circuit (terminal #87a on a standard ISO relay) that would open the circuit only when the ignition switch was in the 'Start' position and eliminate the additional load concern.

 

Assuming you are talking about the gauge of wire supplying the fan itself, I would look at the Taurus cabling and see what gauge the factory used. You could go up one step in wire gauge but I wouldn't get too crazy with it. If you are talking about battery cable gauge I use 1/0 welder wire...finer strands make it more flexible.

 

AWG 8 for 40 amps, or you could double up with two AWG 12 wires in a single loom for aesthetics.

 

Automotive wiring capacity is a bit different than household wiring. Here's a chart and info: http://www.wiringproducts.com/automotive-wire

 

Hmm. I always thought an ampere was an ampere. Of course there is always voltage drop over distance to be considered, ampacity, and type of insulation. You can't argue too much with the NEC. Automotive wiring almost always assumes a ground path through the chassis/body, and battery cables, therefore ancillary circuits are single wire paths for all practical purposes.

 

An Amp is an Amp, but there is a difference between wires sizing for AC and DC.

So you can't really use the NEC/CEC AC wire sizing tables for DC. Not sure about the NEC but the CEC (Canadian Electrical Code) used to have DC wire sizing tables. Least it did in the 1990 edition IIRC.

 

It is the kind of stuff that makes me call BS on all the people on the all-knowing internetz that say, "Taurus/Volvo fans have been PROVEN to pull 80 amps and therefore when wiring for them, you must use(something stupid like..) 0 gauge".

Now I may be overstepping my own bounds a bit here, but I am assuming the electrical engineers at Ford and Volvo both didn't screw up, because both of their fan relays are powered by one single 12 gauge red wire....

...you know what I mean here, guys?

I think people over react and use emotions to build their cars instead of common sense and actual data like the actual engineers/designers use.


Charlie, I was speaking about the battery wire; I will be using 12 gauge wire to feed the fan relay and fans, just as Ford and Volvo did.
Charlie, did you check your visitor messages?


Thanks again everyone.