You would have to be ignorant not to see that horn relay wire is <#10 gauge (on the first page pix). And they upgraded the horn relay "buss" wire for thier application (on second page) so they would have a much larger wire. You would also have to be ignorant not to see the size of the alt wire is <#10 also. And you would have to ignorant not to realize any time u make a mechanical termination you add contact resistance - which drops voltage.
Again - unless can afford to replace alternators frequently - connect your lighting wire to the batt.

cardo0

 

Cardo, sorry if I steamed you with my post, was probly rude. But my point stands, Running a #10 from the alt to a term block for the lights and whatever else you need will bypass the horn circuit completely, all the current required for these devices will then have a shorter path to go, and since the lights/fans/watever only are in use with the engine running, all their current is supplied by the alternator, not the battery. You have a valid point about the contact resistance, however, with a properly crimped/soldered connection that resistance will be negligeable, especially in a short run like I proposed. This will not negatively affect the alternator in any way, and it will lighten the load on an old possibly weakened electrical system.

 

I run a number of direct wires off the back of my alternator. A large number 6 directly to the heavy wire on the solenoid to charge the battery, a number 10 for the headlights and another number 10 for the fans. All directly off the stud on the alternator and only use switches in the car to activate the relays.
I don't believe in shipping power back and forth either and make the shortest runs possible.
Using this method creates the least voltage drop in the car. I have a volteage meter hooked up from the terminal block under the dash. With the old method of doing things everytime I turned on a device the voltage dropped. With the new method of direct hooking to the alternator I see almost no change regardless of the number of devices turned on.

I do run a 150 amp truck alternator.

 

Thats exactly what I am talking about Norval.

 

The alternator is the way to go, especially for big accessories. I'm running my electric fans through a relay connected right to the alternator. I did have to put diodes on the trigger wires because there was some feedback from the relays.

This avoids pulling lots of current through your 30 year old wiring harness. Much better choice than the battery or starter.

MAD sells a handy little wiring block that could mounted between the alt and horn relay.

 

So if someone buys the MAD parts and follows the instructions all is well?

 

Yes, all will be well. Mine would look a little neater than theirs, but basically the same

 

Good stuff!

May I make this suggestion:

Intead of running several wires from the alternator, run an 8 gauge from the alternator to a terminal post (Mad and Jegs has them) mounted next to the wiring harness on the drivers side fender well. Then you have very short runs to your relays and you can continue the #10 from there. You can use that terminal later if you need a power sourse for fans or whatever.

I ran a #8 all the way to the rear (fuel pumps) with terminals at strategic locations on both sides. It's probably overkill, but I have 14+v under all conditions at all locations with no danger of any overheated wire.

 

Just look at all the car stereo guys ( I was in the business for 20 years)-they ALL wire to the battery. The weak link IS the small guage wire on the alternator.

 

 

I agree, thats why the guys big big watt stereos have problems with batteries and charging systems, even with a big amp alternator and THATS why you should run a seperate circuit off the alternator with appropriate sized conductors to run your hardware, and push them with an appropriate sized alternator.
All the current to run big accessories should be coming from the alternator, thats what it is there for, the battery is there to start the engine.

 

I believe the car stereo guys run from the battery is to get CLEAN power. I had to do this to get rid of static.

 

I did not know about the Mad site for the relay setup. My high beam lights would pulse on and off. I replaced the alternator, the dimmer switch and the headlight switch and the problem persisted. Previous posts explained my observation of the headlights (high beam) pulsing on and off. This was caused by a heat-activated disconnect switch in the headlight switch itself (old as well as new switches). An interesting and disappointing design feature. After reading the posts, I bought a small fuse panel, relays and larger diameter wire. I routed new wire from the headlight terminals to the relays and connected the low and high beam wires to the relay. The horn relay feeds the fuse block which is right next to it. Most folks looking under the hood would not notice the changes. The system works great. That is, no more pulsing.

 

Hmm, I didn't know they did that (GM) not a very good design feature from my experience in electrical stuff, should have been 1 protection device for the entire circuit and a more robust switch. The switch should never get hot carrying its load. Sounds like you got a good fix though

 

Yes- they wire to the battery to take advantage of what the battery can do BESIDES start the car.

First the voltage coming from the alternator is NOT clean-It's producing AC then converting to DC. There's where the noise comes from and the battery cleans it up.

Second- the battery smoothes out & isolates the power surges- so when you hit the high beams- the diodes don't explode and your headlight filaments last longer

SO- if your going to run "hot" headlights -GO to the battery to power the relay and make sure you fuse it. And on a Corvette- DON'T use the factory ground-it's way too small guage.

Richard

 

would adding a big capacitor like this help?
http://www.ecklers.com/product.asp?p...dept%5Fid=1013

 

thats not a big capacitor, thats a small noise filter capacitor. Richard had a good point about the filtering aspect of the battery, but I have never heard of any regulators self destructing when load is applied to them (as long as the load is inside the rating od the regulator) These devices are designed to switch on and off at very high speeds and power diodes are designed to do it at 100% load. I'll have to look up some component specs to see what it is tho.

 

"These devices are designed to switch on and off at very high speeds and power diodes are designed to do it at 100% load"


HOWEVER- in the real world -Why do you replace an Alternator? Usually the diodes breakdown after a while. Why? The surges that happen in the car. If you have ever owned a C4, they are notoriuos for burning up alternators. Why? The battery goes south and the alternator can't handle the "real world" loads.

Another question- When do light bulbs usually "blow" in the house? When you flip the switch. Surges are BAD-ANYTHING you can to to protect an electrical device from them is GOOD.

 

apologies to any EEs: just trying to remember right - the current delivered from the alternator is a series of top halves of a sine wave (the bottom half is "made" positive). when the engine revs the most significant change in the curve is the frequency shortens (since voltage is regulated). i can't remember what caused the spikes i used to see.
if this is right, what changes by moving a [headlight power source] connection from one point to another other than the voltage, or "average" voltage, and is it enough to matter to the load? (or is this the wrong question?)

p.s. with regulators located inside of the alt, how much of the alt failure issue is heat?

 

S489, most regulator failures are due to heat with some vibration and overload thrown in as well as being cheap to start with, the diodes usually die first, they either open when they burn or worse, short which is what cause them to kill the battery. You are also correct in your understanding of the regulator/rectifyer function. Spikes are caused by loads switching on and off of the system, reactive loads do it worse than resistive loads (motors = reactive, Lights = Resistive) . This can be dealt with somewhat with filter capacitors across switches, but in a car usually isn't needed. A decent filter network applied to the output side of the alt will kill virtually all the ripple on the DC line that you can measure with an ociloscope.
The C4 alternator had high failure rates because it was underengineered to do the job it was used for AND had cheap parts. Light bulbs in the house usually burn out because the filaments wear out (they switch on and off 120 times a second) and this constant heat/cool expand/contract cycle just plain wears them out. Car lamps die due to heat, vibration, wear and tear.
Today we can get parts that high quality and last a long time and are cheap. Years ago I built regulators and rectifier units that would pass well over 100 amps and live forever, however the components cost several $$ each, now they a buck or less. The Powermaster 140 amp alternators you can get now are MILES and Years ahead of what was the "Latest" Technology in 84 when the C4 was new.

god I get long winded sometimes, sorry guys...