1969 Roadrunner Fusible Link Burning Hot to Touch When Running / Fine With Engine Off / Help Troubleshoot

[j-c-c-62]

So why then even have an "AMMETER" in the first place?
Are they mostly to indicate one has an operational alternator belt?

 

[Nacho-RT74]

The ammeter shows the load status at the battery and, if you analize correctly, you can know where is coming the load being used and of course the alt status (after really understand the ammeter), but the gauge is PRIMARILY a batt status load reader

If discharge… all or most of the load comes from battery… you battery is being discharged. Your alt is not quite enough to keep up the load demands on car.

If charge… alternator is charging back the battery on discharged batt stage and IS BEING ENOUGH to feed the car loads demand

Is zero… the alternator is taking care of all the loads demands and battery is in rest stage. This is the IDEAL stage

This is JUST if car wiring is correct

If you begin to source added accesories from battery, the loads readings begins to be distorted and loads are running through paths weren’t designed to hold that extra load as a constant load stage (for example, the fuse link).

You can get a constant charge reading if alt is good enough but not really charging the battery while really feeding the accs added to the battery side. This is simply wrong and is an unnecessary stress added into the system, special at ammeter and bulkhead.

Then everybody blames the ammeters, while the culprit is the owners/mechs unknownledge

 

[72RoadrunnerGTX]

So why then even have an "AMMETER" in the first place?
Are they mostly to indicate one has an operational alternator belt?

The original primary function of the ammeter is to monitor the health, charge/discharge status of the battery. Batteries from the time tended not to last more than 2-3 years with most failures showing an abnormally high charge rate prior to total failure. And abnormal discharging would indicate a charging system failure. Stock, as original, normal healthy battery and charging system, centered needle, shouldn’t be indicating any load current other than the battery. If you just want to know if the alternator is working, run a stand-alone voltmeter or an idiot light. Any serious monitoring of DC electrical system involves ammeters of some kind; there is a reason why they were designed into this system originally.

 

[j-c-c-62]

............... Any serious monitoring of DC electrical system involves ammeters of some kind; there is a reason why they were designed into this system originally.

I submit "serious" would also include the omitted voltmeter, which unlike an ammeter has no real potential downside. I doubt the original single choice of an ammeter considered the intended reliable safe use for over 5+ decades.

 

[j-c-c-62]

The ammeter shows the load status at the battery and, if you analize correctly, you can know where is coming the load being used and of course the alt status (after really understand the ammeter), but the gauge is PRIMARILY a batt status load reader

If discharge… all or most of the load comes from battery… you battery is being discharged. Your alt is not quite enough to keep up the load demands on car.

If charge… alternator is charging back the battery on discharged batt stage and IS BEING ENOUGH to feed the car loads demand

Is zero… the alternator is taking care of all the loads demands and battery is in rest stage. This is the IDEAL stage

This is JUST if car wiring is correct

If you begin to source added accesories from battery, the loads readings begins to be distorted and loads are running through paths weren’t designed to hold that extra load as a constant load stage (for example, the fuse link).

You can get a constant charge reading if alt is good enough but not really charging the battery while really feeding the accs added to the battery side. This is simply wrong and is an unnecessary stress added into the system, special at ammeter and bulkhead.

Then everybody blames the ammeters, while the culprit is the owners/mechs unknownledge

All meaning what? You left your lights on and the alternator is working to recharge it? A voltmeter would essentially indicate the same info. In reality, the driver can affect it in no real way except keep driving or stop driving.

And a fuse link DOES NOT keep extra load at a constant load stage, it serves as one time partly slow limiter.

 

[72RoadrunnerGTX]

I submit "serious" would also include the omitted voltmeter, which unlike an ammeter has no real potential downside. I doubt the original single choice of an ammeter considered the intended reliable safe use for over 5+ decades.

There would be absolutely no reason to monitor the system voltage while running the stock stand-alone ammeter, correct load placement, if the ammeter needle is centered, the system is balanced, and the alternator is operating at its regulated voltage level. Any change to that voltage level would be indicated by discharge on the ammeter, voltmeter would be useless.

Nothing about these cars were designed to last more than a few years, until the next trade-in. I’ve seen many of these all-stock untouched electrical systems/ammeters in perfect condition many decades on. Add in 5+ decades of abuse, people screwing with system who shouldn’t be, there will be problems with anything. A properly maintained stock electrical system, correctly loaded, has no downside. The ammeter will tell you much more than a voltmeter only can if you understand what it’s telling you. You want to redesign this system, add a bunch of loads, place them at the battery or wherever you want, you should run a voltmeter.

 

[j-c-c-62]

There would be absolutely no reason to monitor the system voltage while running the stock stand-alone ammeter, correct load placement, if the ammeter needle is centered, the system is balanced, and the alternator is operating at its regulated voltage level.

You missed the point, a voltage meter alone pretty much gives a driver all they need to know, no real need for an ammeter. We don't care much if the system is in balance. What are we supposed to while driving, turn off the lights, radio, a/c, etc? We do care if the voltage drops or is dropping.

Any change to that voltage level would be indicated by discharge on the ammeter, voltmeter would be useless.

Discharge that an alternator cannot adequately supply would result in a voltage drop that a meter would indicate in every
case.

Nothing about these cars were designed to last more than a few years, until the next trade-in.

We agree

I’ve seen many of these all-stock untouched electrical systems/ammeters in perfect condition many decades on.

Yet we still read about bulkhead wiring etc failures

Add in 5+ decades of abuse, people screwing with system who shouldn’t be, there will be problems with anything.

So your point is an ammeter is necessary because of people improperly screwing with their electrical systems?
That solution is obvious.

A properly maintained stock electrical system, correctly loaded, has no downside.

Not so sure about. But I am sure with no ammeter in dash, it can't be the source of the problem, that a simple volt meter cannot produce.

The ammeter will tell you much more than a voltmeter only can if you understand what it’s telling you.

Not sure about the much more part, but I do question if the info it is telling you is really pertinent, or more so that a volt meter provides

You want to redesign this system, add a bunch of loads, place them at the battery or wherever you want, you should run a voltmeter.

I agree, just like most modern cars on the road for the past 4? decades.

 

[Canadian1968]

You missed the point, a voltage meter alone pretty much gives a driver all they need to know, no real need for an ammeter. We don't care much if the system is in balance. What are we supposed to while driving, turn off the lights, radio, a/c, etc? We do care if the voltage drops or is dropping

That doesn't make any sense.... if you had a voltmeter and you see your volts dropping what are you going to do ?
VS
You have the ammeter and it shows a discharge , both are telling you the same thing. Actually the ammeter would probably show you something is wrong before the voltmeter would.

 

[72RoadrunnerGTX]

You missed the point, a voltage meter alone pretty much gives a driver all they need to know, no real need for an ammeter. We don't care much if the system is in balance. What are we supposed to while driving, turn off the lights, radio, a/c, etc? We do care if the voltage drops or is dropping.
So your point is an ammeter is necessary because of people improperly screwing with their electrical systems?

Sounds like you may have missed some points as well. We’ll leave it at that. I don’t think the ammeter vs. voltmeter debate is going to end here and now.

Yes, technology has moved on from the time these cars were designed. Batteries became more dependable, more electrical demands from added standard equipment requiring more alternator output capacity. Things changed, that doesn’t mean the engineers who designed this, and all other brand’s, electrical systems back in that time, for the technology of the time, didn’t know what they were doing. I blame the bean counters for the weakness at the charge path bulkhead connectors, nothing to do with the presence of the ammeter.

I’ve put many hundreds of thousands of miles on more recent/modern drivers with voltmeters or idiot lights only, experienced many failed alternators and batteries over that time. Voltmeter gave no indication of abnormal charging rates and possible pending battery failure, it can’t. Just one day it won’t start. Alternator failures, voltmeter showed it stopped working, that’s it, no way to gauge at what rate the battery is discharging, when the vehicle stops running due to a fully depleted battery.

 

[j-c-c-62]

That doesn't make any sense.... if you had a voltmeter and you see your volts dropping what are you going to do ?

Sure it does, Same thing you would do with an ammeter. except you don't need a fire extinguisher to put out the fire started by the bulkhead connector.

VS
You have the ammeter and it shows a discharge , both are telling you the same thing.

Bingo

Actually the ammeter would probably show you something is wrong before the voltmeter would.

Like what, because the time response according to physics must be the same the rate of change might be different, but if you concerned about a belt being tossed, both will indicate, and you will still have to limp home at the worst. Hard to imagine what electrical failure other than a bulkhead connector shorting would occur that would not be fused limited and an alternator could not overpower, but a volt meter would show as an unexplained voltage drain at high currents.

 

[72RoadrunnerGTX]

Sure it does, Same thing you would do with an ammeter. except you don't need a fire extinguisher to put out the fire started by the bulkhead connector.

...a bulkhead connector shorting....

Curious, how many car fires “started by the bulkhead connector” have you experienced or have first-hand knowledge of?

You believe the fairly common resistance caused heat damage around the bulkhead charge path under-rated Packard terminals are the result of a short to ground at the bulkhead terminal? Mis-placed loading at the battery is the number one cause of all stock charge path overloading related connection failures on this original design. The Packard terminals in the charge path just happen to be the weakest link, will be the first to fail when current stressed from mis-placed loading at the battery.

 

[Canadian1968]

Sure it does, Same thing you would do with an ammeter. except you don't need a fire extinguisher to put out the fire started by the bulkhead connector.

If you have installed a voltmeter , unhooked the ammeter and tied those wires together the same weak link at the bulkhead still remains.

Voltmeter or ammeter, if you load the system incorrectly the same weak link is still there . Remember the weak link is the bulk head NOT the gauge.

Now if you have rewired the entire system to skip or bypass the bulk head that's fine , you could have done that AND kept the ammeter and enjoyed the benefits that you don't get with voltmeter .

 

[Crackedback]

It's groundhog day around here again.

The charge system on muscle era mopars have caused issues from the day they rolled off the line. Saying otherwise is just not true. Smoked bulkheads on totally OEM cars was common, especially in hot environments with AC cars. Saw cars that were under 2 years old with issues. A balanced system would provide for adequate alternator output under all conditions, mopars engineers missed the mark.

Want to run an ammeter, run it. Want to run a voltmeter run it.

 

[72RoadrunnerGTX]

It's groundhog day around here again.

The charge system on muscle era mopars have caused issues from the day they rolled off the line. Saying otherwise is just not true. Smoked bulkheads on totally OEM cars was common, especially in hot environments with AC cars. Saw cars that were under 2 years old with issues. A balanced system would provide for adequate alternator output under all conditions, mopars engineers missed the mark.

Want to run an ammeter, run it. Want to run a voltmeter run it.

Don’t you mean fibbing?

Who is saying there hasn’t been issues at the bulkhead charge path Packard’s from early on, especially on higher optioned cars with more factory loads? C-body recall? Considering the original design of bulkhead charge path pass-through in the early sixties was a screw terminal design that did not suffer the later Packard terminal failure rate, hard to blame the engineers and not the bean counters who opted for the later click together Packard bulkhead connector to save a couple of seconds on the assembly line. Have said it for years, the bulkhead under-rated Packards are the weakest link in that charge path, have been failing since these cars were new, be it from optioned factory loads (alternator feed Packard) or added aftermarket mis-placed loads (both alternator and battery feed Packards). Yet in my time at the dealers back then, for every bulkhead connection issue I saw, there were many, there were many more cars that managed to survive unscathed with no issues at all for many years. Common denominator? All stock, well maintained, and nobody screwed with loading.

 

[Nacho-RT74]

All meaning what? You left your lights on and the alternator is working to recharge it? A voltmeter would essentially indicate the same info. In reality, the driver can affect it in no real way except keep driving or stop driving.

And a fuse link DOES NOT keep extra load at a constant load stage, it serves as one time partly slow limiter.

being the amperes the actual force what makes to work everything, the ammeter is a straight reading of what is happening. Not saying the voltmeter doesn’t work too, but ammeter is better for that.

Let’s put it like this, with an example I like a lot to post.

3 guys pushing a car… that’s voltage
The effort every one put to move the car… that’s amperage

Voltmeter will tell you if guys are beginning to sweat due their effort, but ammeter is reading directly the force being applied by each one. When they begin to sweat is a bit later than knowing the effort being applied on real time.

The fuse link shouldn’t get throught it any load to work more than the recharge battery stage if necessary with engine running after get discharged. Of course when engine is off, every accesory being feeded will get its power running through the fuse link but that’s not the regular scenario. If you source accesories from batt post, you are adding more load through the fuse link which is not designed for. This becomes dangerous if while batt is discharged being recharged while alt is able to do it, then also gets loads to feed those accs. Of course, it happens the same to the ammeter.

On this last stage in fact you can get a charge reading still with batt fully charged, where you are not really charging batt but feeding accs on batt side.