Amp Breaker

[318willrun]

A lot of people do a lot of things.
Nothing wrong with the factory setup for factory like you have.
If the car has anything other than the 6012 headlights, then a relay harness powered from the alternator will (a) protect the headlight circuit, (b) provide brighter lights, (c) divert those 9-10 ampos so they never go through the bulkhead connector or the main splice.

A voltmeter doesn't show battery charging or discharging. It shows system voltage at the location its connect to. From that we must assume the charge rate is OK. It doesn't show if the charge rate is 5 amps or 50 amps.
The ammeter doesn't show voltage. We assume when it shows normal charging and discharging that the system is OK, and when it shows something like discharging while the engine is running, the alternator isn't working.

If you like videos, there's a bunch in this thread from a guy delving into this. I didn't watch them but he seems to understand the issues.

very good discussion in the thread you provided. Truthfully, I'm very elementary on wiring and some of it I cannot follow. I do not add electric fans, booming stereos, or such components that may stress the old wiring. If I could (or do I need to??) take some of the load off the bulk head/amp gage in a simple, safe manner I would.

 

[Mattax]

If I could (or do I need to??) take some of the load off the bulk head/amp gage in a simple, safe manner I would.

The guy's videos may be helpful. I agree the diagram he posted is a little confusing at first glance.

Lets just deal with the load on the amp gage with no amps, no plow, no winch.
When driving around, there is no load on the ammeter.
The alternator is producing power at 14 volts. The battery is maintained at full charge with this 14 volts.

After starting, the battery will recharge.

The only load on the ammeter in the discharge direction is when the car is run on battery power (either startup or dead alternator). Even with the heater fan on max and headlights on, the current flowing out will be around 20 - 25 amps. The ammeter can handle that.

The main way to keep excessive loads off the ammeter is to avoid running the battery down.
If the battery is run down it and can't be charged on a charger, then keep the rpms down and the drive distance short. Then let everything cool off. The idea of keeping the rpms down is to control the current by maxing out the alternator's capacity. Alternators don't produce their maximum power until around 1300 to 1500 engine rpm.

Bulkhead connections can get hot. Especially with continous loads over 30 amps.
I think first thing is to clean them and put new seals in.
Second is don't let the battery get too low. LOL. if the car needs a jump, leave it charging on the other guy's car as long as possible.
A headlight relay harness is way to keep 9-10 amps from ever going through the connector (or connectors if the car has an 'engine connector') on the alternator output wire.

Another technique is to spilt the load before it goes through the bulkhead connector. That's what the factory did in '75.
A similar method is to add a second wire from the alternator directly to the ammeter. I did this on my '67 when I had the instrument panel out. A few pics here.

Another way to run a parallel wire is to a spare terminal (if available) on the hot side of the fuse box. This is what the guy was showing with the 'C-body recall'.
Let's draw that into the diagram.

Now there is a second path to the main splice that doesn't go through the bulkhead connector.

As far as the ammeter itself. The ammeter is nothing more than a stamped metal plate with studs pressed in. When electrons move past the needle, the magnetic field created by the electrons moving around the pivot cause the needle to deflect.
The weak point electrically is the pressed fit studs. It's not that weak, but its weaker than the studs or the plate.
Some apparently are better than others. Early 70s cars seem to have the most reported issues and it may relate to the water leaks common in those cars.

 

[318willrun]

The guy's videos may be helpful. I agree the diagram he posted is a little confusing at first glance.

Lets just deal with the load on the amp gage with no amps, no plow, no winch.
When driving around, there is no load on the ammeter.
The alternator is producing power at 14 volts. The battery is maintained at full charge with this 14 volts.
View attachment 1716406231


After starting, the battery will recharge.
View attachment 1716406234

The only load on the ammeter in the discharge direction is when the car is run on battery power (either startup or dead alternator). Even with the heater fan on max and headlights on, the current flowing out will be around 20 - 25 amps. The ammeter can handle that.

The main way to keep excessive loads off the ammeter is to avoid running the battery down.
If the battery is run down it can't be charged on a charger, then keep the rpms down and the drive distance short. Then let everything cool off. The idea of keeping the rpms down is to control the current by maxing out the alternator's capacity. Alternators don't produce their maximum power until around 1300 to 1500 engine rpm.

Bulkhead connections can get hot. Especially with continous loads over 30 amps.
I think first thing is to clean them and put new seals in.
Second is don't let the battery get too low. LOL. if the car needs a jump, leave it charging on the other guy's car as long as possible.
A headlight relay harness is way to keep 9-10 amps from ever going through the connector (or connectors if the car has an 'engine connector') on the alternator output wire.
View attachment 1716406235


Another technique is to spilt the load before it goes through the bulkhead connector. That's what the factory did in '75.
A similar method is to add a second wire from the alternator directly to the ammeter. I did this on my '67 when I had the instrument panel out. A few pics here.

Another way to run a parallel wire is to a spare terminal (if available) on the hot side of the fuse box. This is what the guy was showing with the 'C-body recall'.
Let's draw that into the diagram.
View attachment 1716406241
Now there is a second path to the main splice that doesn't go through the bulkhead connector.

As far as the ammeter itself. The ammeter is nothing more than a stamped metal plate with studs pressed in. When electrons move past the needle, the magnetic field created by the electrons moving around the pivot cause the needle to deflect.
The weak point electrically is the pressed fit studs. It's not that weak, but its weaker than the studs or the plate.
Some apparently are better than others. Early 70s cars seem to have the most reported issues and it may relate to the water leaks common in those cars.

Thanks, this helped me a lot !

 

[Ironmike]

I ran a big red wire from my alt straight to the battery, with the breaker in line. No other mods. Amp gauge now shows nothing. This was explained to me by Supercharged Dart, here. on the forum. Good friend of mine and he was right(electrical genius). You get great charging and it takes all the load off the ammeter.

 

[67Dart273]

I ran a big red wire from my alt straight to the battery, with the breaker in line. No other mods. Amp gauge now shows nothing. This was explained to me by Supercharged Dart, here. on the forum. Good friend of mine and he was right(electrical genius). You get great charging and it takes all the load off the ammeter.

BUT.........You still need the ammeter circuit to be "fixed" so that it can properly conduct power from the start relay into the passenger compartment where power is tapped off. In other words, the big red and big black ammeter wires, the bulkhead connector terminals, and the ammeter, or tie the two together.

AND you did not mention......did you fuse or install a breaker in this new wire?

As I mentioned before, the object of a fuse is to protect the wire, or if it's a piece of delicate equipment, separate, smaller fuses to protect (the wire) and the equipment.

 

[72RoadRunnerGTX]

Has anyone run one of these after the starter relay on their classic? Would want the same amp as alternator I'd assume.
RED WOLF 60 Amp Car Circuit Breaker Fuse Holder W/Manual Reset Switch for Boa... | eBay
I see Steve Dulcich put one on his truck.

As mentioned, size the circuit protection devices to protect the wiring, not the alternator. Nothing wrong with the original 16-gauge fusible link for that application on an all-stock loaded system. Fusible links will absorb the occasional current spike that will trip a fuse or circuit breaker. In the referenced Dulcich video he specifically mentions other modifications to the charging system of that vehicle. The mentioned alternator to battery bypass circumvents the designed circuit protection, very dangerous without other modifications. A lot of misinformation about this original electrical system in circulation, has been for many years. If the videos mentioned are confusing, I would suggest starting with the older diagram-based explanations. Some do get fairly deep into these subjects and depend on some understanding of material covered in the preceding videos.
1972 Road Runner GTX

 

[Ironmike]

BUT.........You still need the ammeter circuit to be "fixed" so that it can properly conduct power from the start relay into the passenger compartment where power is tapped off. In other words, the big red and big black ammeter wires, the bulkhead connector terminals, and the ammeter, or tie the two together.

AND you did not mention......did you fuse or install a breaker in this new wire?

As I mentioned before, the object of a fuse is to protect the wire, or if it's a piece of delicate equipment, separate, smaller fuses to protect (the wire) and the equipment.

I did mention a breaker. In the first sentence of my post. I didn't do anything to my ammeter or bulkhead. All is fine 2 years now.