MAD ELECTRICAL?

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Not sure what you're asking, but I think you're asking about where protection is needed.

Fusible links were used to protect downstream of the battery while allowing occassional high draws for short periods of time. The battery, while only at 12.8 Volts at best, has lots of stored power - enough to turn a starter motor in the freezing cold and enough weld with! That's why the original factory design added in a fusible link to the battery feed, but not on the alternator feed. Also the alternator won't produce power if there a short that prevents the field from getting electricity.

So to figure it where your fuses should go, you need to know the flow of current in your car. This will depend on where the pump and headlight relays get power.
Both MAD and my diagrams above show a vehicle with the stock arrangement (no relays or additonal electric equipment). All of the power for running the car flows through the main junction (splice).
That's what the purple arrows illustrate.
madb-running-jpg.jpg

You can do it yourself for any situation. Start at the highest voltage source of power, and trace where the current must flow through to get to the equipment or lights, and finally ground.
For example, do it for the starting situation. In that case the Battery positive is the highest voltage source. Start from there and follow the path(s) to where the power needs are.
Do the same now to where you've located the relay for the electric pump both for starting and for running. It makes a difference if your relays draw power from the alternator output, the fusebox or the battery positive.
 
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Having been an electrical guy all my life, I think it is fair to say that it is hard to get an answer from an electrical guy that doesn’t have “it depends” in it somewhere. If you ask a mechanical guy a question, you generally get a straight forward answer, not so much in the electrical side of the house.
With that said, I’m not sure there is necessarily a “best” way of improving the electrical wiring. It depends (see what I mean) on what you are trying to accomplish or optimize, how much effort you want to put in it, $$, and your skill level. Even the best modification will not work right if done poorly.
All of the mods in this thread will probably work fine. There are a few big things to watch out for:

1. Make sure EVERYTHING is fused that hooks up to the battery. This can be a fuse or a fusible link. There is a huge amount of power in a car battery. I have melted wrenches across a battery. It will also melt your wiring and start a fire. Very sad to lose a car this way.

My earlier comment on parallel fuses was a little vague. In the first three diagrams in the post, you only need to blow one fuse (or fusible link) to isolate a fault. I the last two diagrams you have to blow two fuses to isolate a fault, and it takes twice as much current. If you are not intentionally trying to double your current maximum for some reason, like a killer car stereo, maybe you shouldn’t do it. Once again, it is not a bad mod to increase current if you need it, but twice as big of a fuse is twice as much risk ( sort of).

2. High current connections ( above about 10 amps) must be done well, or they will overheat an burn up. Make sure your crimp lugs and splices are tight and solid. Pull hard on them after you crimp them. Some number of mine fail this test & I think I am good at it (maybe not...). I like to solder them, but that is not in everyone’s skill set.

3. Make sure your wiring has good physical protection. Use grommets on holes in metal to prevent shorts. Keep wiring away from exhaust manifolds and things that move. Don't pull it tight, leave some slack for stress relief.

4. The bulkhead connections are a well known weak link, and will probably fail on you if you don’t deal with them. You can bypass them or replace them as shown in this thread, just keep it fused.

I like my amp meter, so I am partial to designs that leave it operational. Personal preference.

While we are taking bulkhead connections, the other one that fails is the ignition power. Might be good to eliminate the bulkhead connection or bypass it while you are there. I think it is on the same connector on mine.

5. Modifications to the car. If you add or change something from stock, that can have an effect on the electrical system. If you replace your 30 amp alternator with a 100 amp unit, then your wiring may not be adequate anymore, even though it hooks up the same.

6. If you are not an electrical guy and all this makes your brain hurt, you can buy ready made wiring from at least one guy on this forum who has a lot of good feedback. Sometimes it is worth paying somebody else to do some of the thinking for you.
 
Mike69cuda said:
Having been an electrical guy all my life, I think it is fair to say that it is hard to get an answer from an electrical guy that doesn’t have “it depends” in it somewhere. If you ask a mechanical guy a question, you generally get a straight forward answer, not so much in the electrical side of the house.
With that said, I’m not sure there is necessarily a “best” way of improving the electrical wiring. It depends (see what I mean) on what you are trying to accomplish or optimize, how much effort you want to put in it, $$, and your skill level. Even the best modification will not work right if done poorly.
All of the mods in this thread will probably work fine. There are a few big things to watch out for:

1. Make sure EVERYTHING is fused that hooks up to the battery. This can be a fuse or a fusible link. There is a huge amount of power in a car battery. I have melted wrenches across a battery. It will also melt your wiring and start a fire. Very sad to lose a car this way.

My earlier comment on parallel fuses was a little vague. In the first three diagrams in the post, you only need to blow one fuse (or fusible link) to isolate a fault. I the last two diagrams you have to blow two fuses to isolate a fault, and it takes twice as much current. If you are not intentionally trying to double your current maximum for some reason, like a killer car stereo, maybe you shouldn’t do it. Once again, it is not a bad mod to increase current if you need it, but twice as big of a fuse is twice as much risk ( sort of).

2. High current connections ( above about 10 amps) must be done well, or they will overheat an burn up. Make sure your crimp lugs and splices are tight and solid. Pull hard on them after you crimp them. Some number of mine fail this test & I think I am good at it (maybe not...). I like to solder them, but that is not in everyone’s skill set.

3. Make sure your wiring has good physical protection. Use grommets on holes in metal to prevent shorts. Keep wiring away from exhaust manifolds and things that move. Don't pull it tight, leave some slack for stress relief.

4. The bulkhead connections are a well known weak link, and will probably fail on you if you don’t deal with them. You can bypass them or replace them as shown in this thread, just keep it fused.

I like my amp meter, so I am partial to designs that leave it operational. Personal preference.

While we are taking bulkhead connections, the other one that fails is the ignition power. Might be good to eliminate the bulkhead connection or bypass it while you are there. I think it is on the same connector on mine.

5. Modifications to the car. If you add or change something from stock, that can have an effect on the electrical system. If you replace your 30 amp alternator with a 100 amp unit, then your wiring may not be adequate anymore, even though it hooks up the same.

6. If you are not an electrical guy and all this makes your brain hurt, you can buy ready made wiring from at least one guy on this forum who has a lot of good feedback. Sometimes it is worth paying somebody else to do some of the thinking for you.
Click to expand...
 
I am not worried about doing the work, more worried that it won't fix the problem of the charging system fluctuating and bouncing the Volt meter around. I got a new battery and that helped a lot, the charging system seems to work fine going down the road with a steady 14 volts, at idle it starts fluctuating. Thanks for your response
 
Thanks for amplifying!
Mike69cuda said:
I the last two diagrams you have to blow two fuses to isolate a fault, and it takes twice as much current.
Click to expand...
In fact, when he realized that, NachoRT went to a single link on his battery side parallel lines (the one repeated below). I just don't have an updated illustration on hand.
parallel-redrawn-jpg.jpg
 
Mattax said:
Not sure what you're asking, but I think you're asking about where protection is needed.

Fusible links were used to protect downstream of the battery while allowing occassional high draws for short periods of time. The battery, while only at 12.8 Volts at best, has lots of stored power - enough to turn a starter motor in the freezing cold and enough weld with! That's why the original factory design added in a fusible link to the battery feed, but not on the alternator feed. Also the alternator won't produce power if there a short that prevents the field from getting electricity.

So to figure it where your fuses should go, you need to know the flow of current in your car. This will depend on where the pump and headlight relays get power.
Both MAD and my diagrams above show a vehicle with the stock arrangement (no relays or additonal electric equipment). All of the power for running the car flows through the main junction (splice).
That's what the purple arrows illustrate.
View attachment 1715218980
You can do it yourself for any situation. Start at the highest voltage source of power, and trace where the current must flow through to get to the equipment or lights, and finally ground.
For example, do it for the starting situation. In that case the Battery positive is the highest voltage source. Start from there and follow the path(s) to where the power needs are.
Do the same now to where you've located the relay for the electric pump both for starting and for running. It makes difference if your relays draw power from the alternator output, the fusebox or the battery positive.
Click to expand...
Thanks for reply..
 
coalman said:
I am not worried about doing the work, more worried that it won't fix the problem of the charging system fluctuating and bouncing the Volt meter around. I got a new battery and that helped a lot, the charging system seems to work fine going down the road with a steady 14 volts, at idle it starts fluctuating. Thanks for your response
Click to expand...
The maximum alternator output depends on rpm. The regulator will try to hold the output voltage at 14 Volts but if the power demand exceeds the maximum power it can produce at that rpm, the output voltage will drop. If the voltage drops to 12.8, its likely the battery is supplying a portion of the power.

Low rpm power output can be improved in various ways if needed. Beware that sometimes a higher output alternator has worse low rpm performance.

Here's an example showing the dependency of power output on rpm. Its a test report that came with a reman'd late squareback chrysler alternator.
A few things to be aware of:
1. RPM is alternator rpm, not crank rpm.
2. Output current in a test can be changed by altering the voltage. ( In this test the voltage was regulated to 13.2 Volts.)
3.a. Rating is usually given near maximum but I've not seen an industry standard.
3b. Chrysler's FSM tests for output are usually done around 1250 engine rpm with voltage controlled by a carbon pile. When you see that in the book, its not the same as the 'rating'.
output%20chart.jpg
 
Do you still have the mechanical voltage regulator? Those are notorious for jumping the charge voltage around. Could be a bad regulator even if it is a solid state one. Or possibly an alternator. Is it jumping around enough that you can see it in the headlights at idle? If not, maybe your voltmeter is just a little sensitive.
 
Mike69cuda said:
Do you still have the mechanical voltage regulator? Those are notorious for jumping the charge voltage around. Could be a bad regulator even if it is a solid state one. Or possibly an alternator. Is it jumping around enough that you can see it in the headlights at idle? If not, maybe your voltmeter is just a little sensitive.
Click to expand...

I had a new solid state, and replaced it with a mech. same results, the alternator is not that old I replaced it a while back. I suppose I can take it down and have it checked off the car. Thanks for your help!!
 
No problem, I have learned a lot from this forum & would like to contribute when I can.
 
I really used to like ammeters, but the fact is that NObody that I'm aware of, had (back in the day) come out with a decent system that wasn't somewhat or a lotta'what "numb." Some of the Fords you could turn the headlights on/ off and you'd look at the ammeter and there would be a huge question "did it move?"

I'm speakin of the later "external shunt systems. These actually USED the voltage drop present in the factory harness to send readings to a sensitive meter
 
Yeah, I heard that they intentionally designed them crappy so that people would not get excited if the needles moved around too much. The no numbers on the scales helped along the crappy theme too. Kinda defeats the purpose of a gauge if it doesn’t really tell you much doesn’t it.....
 
Thanks again, also does it matter where the fusible links are in the wire run? It looks like it will be crowded at the starter relay.
 
For maximum protection the fuse (fusible link) should be as close to the power source as practical. This lowers the risk of damage from a short in the wiring before the fuse. Right off the starter relay is the best point for the fuse.

Like in a house, in a car electrical system there are “main fuses” and sub circuit fuses ( breakers in a house). In a house the power comes in and goes through the main breaker first thing. Then it goes to the sub circuit breakers. The main breaker keeps your house from taking down the power grid. The sub circuit breakers protect the circuits in your house.

Same in a car. The fusible link is the “ main breaker “ equivalent in a car. From there the power goes to the fuse box. The fuse box can be located some distance away from the power source, since the wiring to it is protected by the fusible link. The fuses in the fuse box protect the individual circuits and keep one short from taking down the whole car electrical system. The fusible link keeps you from shorting out the battery in case of a short before the fuse box. An unfused short on a car battery is likely a fire.

Sorry for the long winded answer, but once you figure out what the designers were trying to do with wiring, a lot of the electrical stuff isn’t that hard, it is just not obvious sometimes.
 
Thanks for your time, done the car today it is wired like MAD directed. I did install a 10 gauge wire to replace the 12 off the alternator with the correct fusible link at the relay along with the other one. I don't like the looks of the two 12 gauge wires spliced together.
I have not hooked up the battery yet I am going to OHM check everything in the morning, too hot in the garage right now... Thanks again to everyone else too!!!
 
Oh well, back to square one. Ran the car this morning, still have pulsating charging, might even be a little worse. Any suggestions??? I sure need them, Thanks
 
There's no way to know if the charging is pulsing. You would need an ammeter on the charge wire to know that.
What you're seeing on the voltmeter is system voltage fluctuating.

There are a few possibilities.
The alternator at idle is just at the minimum speed to 'turn on' so voltage is fluctuating between alternator output and battery voltage.

The alternator at idle speed is producing less power than is being demanded.
example:
Lets say the alternator can produce 10 amps at idle;
and the ignition needs 2 amps, the field current 3 amps, and the electric fuel pump 6 amps for a total of 11 amps.
The alternator can't supply the 11 amps so the voltage drops.

example part 2:
Lets say the alternator can't supply the power needs at idle, voltge drops below 13 V or so and the battery supplies a portion of the power. As a result the battery will recharge when the alternator is spinning faster and can do so and if not recharged, it will be trying to suck power whenever the alternator voltage is above the battery's voltage. Until the battery is recharged, its becomes an added demand on the alternator's output.
Taking the example above,
ignition needs 2 amps,
field current 3 amps,
fuel pump 6 amps
recharging 1 amp
for a total of 12 amps.

Ripple voltage which is the left over wave of AC current being rectified to DC. Really shouldn't see that unless a diode is bad.
 
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Not sure if you're following.
Power flows from high voltage to low. If we were discussing water, it's like having a well pump and water storage tank; and the well pump can supply up to 10 gallons per minute at 14.5 psi. Until the water tank is full, some of those possible 10 gal/min will go to filling the tank. If someone is taking a shower and another is washing dishes there might not be enough flow to do all three things at 14.5 psi.
 
The ammeter is like having a flow meter on the line to the water tank. It shows gallons per minute in or out of the tank.
The voltmeter is like the pressure gage on the system.
 
Just frustrated right now, I read somewhere here that the ignition switch could cause this? Thanks
 
My two cents worth: if wiring were causing your fluctuations, you would have a lot of other problems, like smoking connections or the car wouldn’t run right, or other electrical things also would malfunction.
If you can see it in the headlights, that means it is really happening and not a voltmeter issue. It is possible that you could have made it worse by improving your wiring. If you follow Mattax’s water analogy, if you install a bigger pipe you will move more water faster. A bigger wire from the alternator might make the fluctuations more visible.

I agree with mattax, I think your charging system is the issue. An alternator can have some burned out diodes and still operate but not correctly. A regulator, even a new one can be defective. One can even take out the other. Having the alternator tested would be a good idea. If you replace it, change the regulator too.

The wiring is different on the old mechanical regulator and the solid state one, unless it is designed to as a drop in to directly replace the old mechanical one.

The charging circuit does not go through the ignition switch, so I think that would be a long shot.

If it goes away when you rev it up, seems almost certain to be the alternator or regulator.
 
Thanks a lot, I hope I can figure it out, just part of having an old car...
 
My hardest riddles always seem obvious once I figure them out. Usually there are a bunch of clues I have missed / ignored because they weren’t what I was looking for. But if we didn’t enjoy the challenge, we wouldn’t be doing this!
 
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