Happy then disappointed…

[Tony 69]

Update to add to the conversation. I just got off the phone with Evans who makes wiring harnesses and he said going to a 60Amp is no problem. The wiring harnesses are the same. So i may forget the smaller pulley and just upgrade the alternator.

 

[kiwigtx]

Amperage is definitely a real word , but I suspect you must know that.

As a sparky, I just don't use the word.

And just something else in general........ bulbs grow in the garden.

 

[Davefinan]

As a sparky, I just don't use the word.

And just something else in general........ bulbs grow in the garden.

Yes sir. Lamps it is.

 

[Geoff 2]

What I said in post #16.

The alt does not output it's max current at idle & low speeds, which is when the fan is going to be drawing it's 20 amps. Battery may actually be discharging because more current is being drawn from the battery than the alt is outputting. This [ lower battery voltage ] can affect the ign system, cause rough running at idle.
Fix is:
- smaller alt pulley
- higher amp rated alt.

 

[Don Frelier]

Also a dual field alternator with a newer solid state regulator will put out more current at idle than the old mechanical style regulator.

 

[Tony 69]

Ok
Thanks everyone. I’m going to start with a 70amp square back I purchased today and see what happens before I change the pull-up size. Still haven’t located a pulley. I have added a 10 gauge wire from alt to starter relay and kept the existing wire to the bulkhead connector. Can I ground either field terminal? Not sure about that part. And later will add the electronic voltage regulator if needed. Sounds cheap but kids still in college, on a budget for now. Thanks

 

[Tony 69]

Never mind that last post. Tired of thinking about it and trying to rig up something that may or may not work. I grabbed a couple alts today for a 71 RR (if I remember right) These alternators are visually different and the higher amp one might not fit. So, I probably should just go with the power master round back and be done with it. And the VR too. Do you recommend summit or jegs? I attach some pics so you see what I mean and maybe will help someone else

 

[Aron Gleason]

All I run is a ac delco alternator 1 wire. I think it may put out 45 amps, and I'm running a electric fuel pump...msd ignition, electric fan. Been on the car for about 18 years. And no....not spoken like a plumber.

 

[Old Sparky]

A 35 amp alternator is not worth the trouble install it.
Makes a good anchor tho.

 

[GTXDAN]

Going to a bigger alt should help the problem, but you still need to put a relay in the fan circuit. I'm surprised that switch you're using hasn't melted down with that much load going through it. Mounting a relay in the engine compartment and using the switch to control the relay is the correct way to wire those fans, unless you use a temp control switch mounted in the cooling system.

 

[Sparky Anderson]

Spoken like a Plumber.

Sorry, but with respect I have to disagree....no red X.....

*******************
A relay cannot drop the 'amperage' (not even sure if that's a real word yet). A relay is a device used to divert the 'current' away from the switching mechanism, directly to the load. (fan in this case)

A switch typically is used for switching the relay coil, which consumes a fraction of the current of the of the load being controlled.

A switch can be used for switching the load directly, but the switch contacts must be rated for the appropriate load, and voltage as well as number of operations it will be used to switch the load.

A fuse is the device used to prevent to break the circuit in the case of an overload of current to the load.

The fuse does not control the current flow - it is only there as a safety device to cut the circuit.

Current flow if controlled by either a limiting resistor, or the load itself. However, if the load (fan in this case) becomes compromised by a short circuit, then control is lost, and the current increases dramatically, and rapidly, and this is where the fuse operates.

Electrical work is not easy, and caution should be exercised by those who are not sure of what they are doing. It frightens me sometimes when I see guys installing their own electrical mains supplies and distribution panels at home here.


BTW, I am not the expert, I am sure others will want to add their 5 cents worth. I'm just an ordinary Electrician with 40+ years under my belt.

He's right, I can back him up on that one because I am also an Electrician by trade.

 

[Aron Gleason]

Going to a bigger alt should help the problem, but you still need to put a relay in the fan circuit. I'm surprised that switch you're using hasn't melted down with that much load going through it. Mounting a relay in the engine compartment and using the switch to control the relay is the correct way to wire those fans, unless you use a temp control switch mounted in the cooling system.

I agree with you. But I like to be able to flip a switch to turn the fan on/off.

 

[Lefty71]

agree with you. But I like to be able to flip a switch to turn the fan on/off.

Flex-a-lite used to have a way to do both, in one.... I had a van rigged that way once. I wanted the control, as you say, but I wanted the automatic sense set a little higher for a fail-safe.

 

[Tony 69]

Thank you everyone for your input. I tho k I got it now. However, can someone explain the plumber jokes ? I’m not get. And I did get the solid state relay by the way.

 

[Aron Gleason]

Thank you everyone for your input. I tho k I got it now. However, can someone explain the plumber jokes ? I’m not get. And I did get the solid state relay by the way.

Sounds like a ridiculous joke that makes no sense

 

[Lefty71]

The plumber joke thing means "clearly this isn't your field of work" and I'm sure was only
Iightheaterdly directed at those who posted sketchy instructions.
No one in their right mind would actually poke fun at plumbers....life would be hell without them lol.

 

[JC Boatguy]

Allow me to add my two cents. First, a relay on a high amp draw is always a good idea. The reason, let's say you have a long distance between the ignition and the starter, if you use a relay, you don't have to push the current all the way to the key and all the way back to the starter you just have to get it to the relay and IT can carry the higher load..
Also, A relay can be easily wired to provide automatic AND manual operation. But you need to be familiar with relays. Note: Did you know many relays use a common wiring configuration?

 

[GTXDAN]

Painless wiring makes a great fan relay kit with a 40A relay and wiring and a breaker too. Everything to put a relay in your system for only $26. Not pushing you, just don't want to see your car burn down for the want of a relay.

Painless Wiring

 

[Tony 69]

Yes I am knowable on relays. I guess I never thought about it that deeply (current going a shorter distance). I will check GTXDAN recommendation at painless too. Also wondering if an electrical pro can state what a 16 gauge fusible link equals in a fuse size.

 

[blue69runner]

I agree with all that was stated. Just remember supply and demand. Think a larger amp alt is the answer. There is a way to run a larger wire to the battery from the alt. To keep the load off your bulkhead connector.