Diagnosis MOPAR Charging System

[72RoadrunnerGTX]

Jumper cables.

Crank it over and the engine goes into high idle once it starts and that 120+ amps that the alternator is capable of pumping out goes THROUGH the ammeter to that battery that is sucking it through the 60-rated ammeter and, thus, turning it into a fuse.

If you have problems with your ammeter circuit, that ain't all that's wrong.
All of the power to run your car comes through that bulkhead connector and, before the ammeter, it splits off and services all of the vehicle's circuits. The only current flowing through the ammeter after you replace the voltage lost during starting the vehicle is just a trickle charge on the battery.

Bypassing the alternator circuit with an under-the-hood shunt does absolutely NOTHING to remedy the loss of current-carrying capacity of the marginal bulkhead connectors.

You haven't fixed the REAL problem, you've just kluged up a symptom-elimination patch.
Every electrical system in the vehicle depends on good, tight bulkhead connections.
Loose and dirty bulkhead connections get hot with use.
Every time you use the heater, wipers, headlights, etc., you are deriving your current through these faulty bulkhead connections.

The ONLY thing you have eliminated with the shunt is the ammeter itself which wasn't the problem in the first place because ALL of your system loads are tapped into the alternator circuit BEFORE passing through the ammeter.
The ONLY time current passes through the ammeter is:
(1) when the engine ISN'T running in which case the battery is supplying the current.
(2) the alternator isn't charging, again, in which case the battery is supplying the current.
(3) when the alternator is replenishing the voltage drained off during start-up and,
(4) once that has stabilized, the voltage regulator keeps the alternator output just barely over the the current being used by ALL of your electrical systems and is trickle charging your battery.

You DON'T need an ammeter to run a charging system. You can use a volt meter, instead, to monitor the condition of the charging system. That's why Powermaster exists. Their method of connecting the alternator directly to the battery DOES work and is a valid method for their application but, and that's a big "but" if you try and use their technology on an older ammeter style circuit as a repair for dim headlights, slow wipers, etc., you had better make damn sure that the power getting inside the cabin is not being compromised by worn, overheated and/or corroded bulkhead connectors.

Adding your own shunt or switching to a high amperage Powermaster alternator is not a valid substitute for inadequate bulkhead connections. You also have to address to real reason for the "upgrade" and replace the brass terminals in the bulkhead connector. (or replace the under dash and engine bay harnesses)

Basic charging system with an ammeter.



The shunt does NOTHING to repair the poor connections in the bulkhead connector and the current STILL has to pass through that connector regardless of whether there's a home made shunt or a Powermaster alternator.

Ok, one more time, 90 percent of what is posted here, I can’t/don't disagree with. Remaining points of contention, first, there are no published ratings for these ammeters. The cross-section of the brass ammeter internal bus, at its narrowest point, roughly equates to the cross-section of 8-6 ga solid core copper wire, the ammeter is not going turn into a fuse before all supporting 12ga wiring, terminal connections, Packard terminals light up first under the described extreme case scenario. With good tight stud connections, these original passenger car ammeters from this time will handle a great deal of current for short periods of time, will not turn into a fuse by any means before all other related stock conductors in that circuit burn up first.

At the risk of repeating myself yet again, the described battery to alternator shunt wire, overlaying the original stock charge path, not only shunts the ammeter, it shunts the entire stock charge path, removes the bulk of the charging current off the bulkhead Packards, leaving only the vehicle loads on the Packards but now splits the vehicle loads between the two sets of Packards, reducing current loads though the Packards (good thing). The REALLY BAD THING is it also shunts the stock circuit protection (the fusible link) for all remaining stock unfused 12ga wiring and components. Raises the overcurrent limiting level for the entire system by many fold thanks to Kirchhoff's current divider rule. In the event of a short circuit anywhere in the system, wires will burn with that shunt wire in place.

Once more, Post #32

 

[ynst]

The current flowing through the alternator output wire supplies very little current to a battery that's had it's initial drain replenished in the first few minutes after starting the car.

The addition of a shunt alters the current-flow path that supplies the power to the vehicle.
The majority of the alternator's output used to go straight through the firewall to the fuse box, power seat circuit breaker, headlight switch (not parking lights), ignition switch but, then back out to the starter solenoid/relay battery post on a second terminal in the bulkhead connector.
With the shunt installed current still runs in through the firewall plug but on the old "output" wire, instead.

In the past I've bypassed (put all the wires on one terminal) a couple of ammeters in MoPars and more than I can remember in early Chevrolets when the owners installed high amperage, internally-regulated, marine style, alternators to run cooling fans, audio amplifiers, and MSD 6AL boxes to run their ignitions but, simply, replaced the factory alternators with these higher amperage internally-regulated GM alternators connected to the factory wiring.

Every one of the ammeters I had to bypass were fried but we left them in the dash so as to maintain the appearance of a stock system and replaced the high-current Packard 56 style bulkhead terminals to maintain the current carrying capabilities of the circuits. Simply moving the wire from the battery side of the ammeter and placing it on the alternator side turns the ammeter into an ornament but retains all of the under-dash circuitry.

A volt meter, usually hidden in the glove box because the owners preferred that arrangement, was used to monitor the charging system.

The problem with the MSD, if it's wired correctly, is that it is connected to the battery terminal at the starter to help eliminate electronic noise interference and to provide sufficient current to run the MSD. This arrangement causes the MSD to get it's power from the battery side of the ammeter and it raises the current flow through the ammeter when the engine is running. The ammeter will never center itself if there's a corectly-wired MSD in the vehicle.

Many high output amplifiers also need to be conneced right to the battery and these increase the ammeter current flow as well.

A lot of these guys stored their vehicles all winter (we don't drive collector cars in the winter up here on salt-covered New England roads) and the batteries are not always up to snuff in the spring time to start the car so out comes the jumper pack. These checkbook car collectors aren't mechanics and when the car starts, they start racing the engine for a while. (great for the dry engine bearings, too)

I used to be able to smell the burned ammeters but I've lost my sense of smell but these guys sometimes tell me about "smelling something and, now the car won't start" and when I go look, the car won't start because the "fuse" between the battery and the ignition switch is what smelled.
What fuse, you ask?
The ammeter, when they blew it out running the engine too fast when the battery was dead.
As long as the engine was running and the alternator was charging, everything was fine but once the engine was shut off, the current path back to the ignition switch was broken by the burned out ammeter.

 

[72RoadrunnerGTX]

The current flowing through the alternator output wire supplies very little current to a battery that's had it's initial drain replenished in the first few minutes after starting the car.

The addition of a shunt alters the current-flow path that supplies the power to the vehicle.
The majority of the alternator's output used to go straight through the firewall to the fuse box, power seat circuit breaker, headlight switch (not parking lights), ignition switch but, then back out to the starter solenoid/relay battery post on a second terminal in the bulkhead connector.
With the shunt installed current still runs in through the firewall plug but on the old "output" wire, instead.

In the past I've bypassed (put all the wires on one terminal) a couple of ammeters in MoPars and more than I can remember in early Chevrolets when the owners installed high amperage, internally-regulated, marine style, alternators to run cooling fans, audio amplifiers, and MSD 6AL boxes to run their ignitions but, simply, replaced the factory alternators with these higher amperage internally-regulated GM alternators connected to the factory wiring.

Every one of the ammeters I had to bypass were fried but we left them in the dash so as to maintain the appearance of a stock system and replaced the high-current Packard 56 style bulkhead terminals to maintain the current carrying capabilities of the circuits. Simply moving the wire from the battery side of the ammeter and placing it on the alternator side turns the ammeter into an ornament but retains all of the under-dash circuitry.

A volt meter, usually hidden in the glove box because the owners preferred that arrangement, was used to monitor the charging system.

The problem with the MSD, if it's wired correctly, is that it is connected to the battery terminal at the starter to help eliminate electronic noise interference and to provide sufficient current to run the MSD. This arrangement causes the MSD to get it's power from the battery side of the ammeter and it raises the current flow through the ammeter when the engine is running. The ammeter will never center itself if there's a corectly-wired MSD in the vehicle.

Many high output amplifiers also need to be conneced right to the battery and these increase the ammeter current flow as well.

A lot of these guys stored their vehicles all winter (we don't drive collector cars in the winter up here on salt-covered New England roads) and the batteries are not always up to snuff in the spring time to start the car so out comes the jumper pack. These checkbook car collectors aren't mechanics and when the car starts, they start racing the engine for a while. (great for the dry engine bearings, too)

I used to be able to smell the burned ammeters but I've lost my sense of smell but these guys sometimes tell me about "smelling something and, now the car won't start" and when I go look, the car won't start because the "fuse" between the battery and the ignition switch is what smelled.
What fuse, you ask?
The ammeter, when they blew it out running the engine too fast when the battery was dead.
As long as the engine was running and the alternator was charging, everything was fine but once the engine was shut off, the current path back to the ignition switch was broken by the burned out ammeter.

For the purpose of clarity, let’s stick to only the all-as-stock Chrysler ammeter-based charging system discussed here without all of the mentioned added aftermarket misplaced loading at the battery. Typical heat damaged Chrysler ammeters are the result of the combination of resistance at the internal bus to terminal stud head connection, loose stud nuts, and/or current levels well beyond what they were designed to handle, mostly from the described misplaced loads at the battery, they don’t open like a fuse. Terminal abuse, loose nuts, damaged insulators, the added current from loads connected at battery lead to most all heat related ammeter failures, has always been the case. In my humble experience, never saw one ammeter, or ammeter connection, failure not directly caused by abuse at the terminals or misplaced loading at the battery subjecting the ammeter and related circuit conductors to current levels well beyond battery charging and what it was designed to handle.

Voltmeters? To monitor the charging system? Useless really, can get an idiot light to tell you the same information, as to whether or not the alternator is functioning. There is way more real time monitoring information from an ammeter if you understand what its telling you, again only when loaded correctly.

Well aware and understand why many aftermarket equipment manufacturers want direct power connections at the battery, for 99.9% of all vehicles on the road today, no issue whatsoever but it causes problems for this as-stock charging system. Guess what, I run high output alternators, MSD, fuel pumps, EFI, audio amps and several other added loads, with nothing connected directly to the battery and a factory battery ammeter on all of my builds, it can be done safely.

Speaking of safety, a bunch more words typed there, still not one word addressing the severe danger the shunt wire bypass adds to the stock system because it “shunts” the factory circuit protection as well.

 

[RJRENTON]

For the purpose of clarity, let’s stick to only the all-as-stock Chrysler ammeter-based charging system discussed here without all of the mentioned added aftermarket misplaced loading at the battery. Typical heat damaged Chrysler ammeters are the result of the combination of resistance at the internal bus to terminal stud head connection, loose stud nuts, and/or current levels well beyond what they were designed to handle, mostly from the described misplaced loads at the battery, they don’t open like a fuse. Terminal abuse, loose nuts, damaged insulators, the added current from loads connected at battery lead to most all heat related ammeter failures, has always been the case. In my humble experience, never saw one ammeter, or ammeter connection, failure not directly caused by abuse at the terminals or misplaced loading at the battery subjecting the ammeter and related circuit conductors to current levels well beyond battery charging and what it was designed to handle.

Voltmeters? To monitor the charging system? Useless really, can get an idiot light to tell you the same information, as to whether or not the alternator is functioning. There is way more real time monitoring information from an ammeter if you understand what its telling you, again only when loaded correctly.

Well aware and understand why many aftermarket equipment manufacturers want direct power connections at the battery, for 99.9% of all vehicles on the road today, no issue whatsoever but it causes problems for this as-stock charging system. Guess what, I run high output alternators, MSD, fuel pumps, EFI, audio amps and several other added loads, with nothing connected directly to the battery and a factory battery ammeter on all of my builds, it can be done safely.

Speaking of safety, a bunch more words typed there, still not one word addressing the severe danger the shunt wire bypass adds to the stock system because it “shunts” the factory circuit protection as well.

EXCELLENT PRESENTATION.......personally, 90% of your audience does not/cannot understand what you've presented......only words like: ammeter shunt wire, one wire alternator systems, short circuit protection seems to sink in or partially understood.....taking into account the words of others seems to be all that's understood.....just a personal observation......
BOB RENTON

 

[ynst]

For the purpose of clarity, let’s stick to only the all-as-stock Chrysler ammeter-based charging system discussed here without all of the mentioned added aftermarket misplaced loading at the battery. Typical heat damaged Chrysler ammeters are the result of the combination of resistance at the internal bus to terminal stud head connection, loose stud nuts, and/or current levels well beyond what they were designed to handle, mostly from the described misplaced loads at the battery, they don’t open like a fuse. Terminal abuse, loose nuts, damaged insulators, the added current from loads connected at battery lead to most all heat related ammeter failures, has always been the case. In my humble experience, never saw one ammeter, or ammeter connection, failure not directly caused by abuse at the terminals or misplaced loading at the battery subjecting the ammeter and related circuit conductors to current levels well beyond battery charging and what it was designed to handle.

Voltmeters? To monitor the charging system? Useless really, can get an idiot light to tell you the same information, as to whether or not the alternator is functioning. There is way more real time monitoring information from an ammeter if you understand what its telling you, again only when loaded correctly.

Well aware and understand why many aftermarket equipment manufacturers want direct power connections at the battery, for 99.9% of all vehicles on the road today, no issue whatsoever but it causes problems for this as-stock charging system. Guess what, I run high output alternators, MSD, fuel pumps, EFI, audio amps and several other added loads, with nothing connected directly to the battery and a factory battery ammeter on all of my builds, it can be done safely.

Speaking of safety, a bunch more words typed there, still not one word addressing the severe danger the shunt wire bypass adds to the stock system because it “shunts” the factory circuit protection as well.

I totally agree with the volt meter being useless as a charging system monitor but when Detroit started building higher capacity charging systems they switched to volt meters and idiot lights as the ammeter technology was limited to 65-ish amp systems.

100 amp internal-shunt ammeters are available but they need to be hung under the dash.

Powermaster alternator instructions, I believe, stress the inclusion of a fusible link or a mega fuse or similar large capacity fuse in the 8 gauge shunt wire.
The MoPar fusible link on the supply line going into the bulkhead will protect the vehicle wiring and fuse or fusible link on the alternator output will protect against a full-fielding, runaway, alternator.

As-stock charging systems should be kept as-stock not semi-upgraded to later technology. If you want to do that, have someone build you a resto-mod.

Me, I'll keep the stock configuration and maintain the integrity of terminals and components. If I want to add something that draws a lot of current, that'll be connected to the charging system before (electrically) the alternator and most likely under the hood with weatherproof connectors.

If something that I want will require an alternator output upgrade, I'll pass on adding it. If my stock alternator ever full-fields itself, it won't overpower the ammeter like some of these newer alternators would.

 

[72RoadrunnerGTX]

Powermaster alternator instructions, I believe, stress the inclusion of a fusible link or a mega fuse or similar large capacity fuse in the 8 gauge shunt wire.
The MoPar fusible link on the supply line going into the bulkhead will protect the vehicle wiring and fuse or fusible link on the alternator output will protect against a full-fielding, runaway, alternator.

There it is, forget everything else for a sec, I think you are missing the key point here. It does not matter if the shunt wire has its own circuit protection device or not. The shunt wire, fused or not, provides for a parallel current path around the stock fusible link. Should a short happen anywhere in the stock unfused wiring or components, the total amount of current needed to open both of the now paralleled circuit protection devices (stock fusible link and whatever breaker or fuse is in the shunt wire) will far exceed the ampacity of the stock conductors/wiring, wires will burn. The designed circuit protection for the stock wiring is effectively defeated with this shunt wire in place! I have posted twice now in this thread a video link where this is demonstrated. Circuit protection matters.

 

[ynst]

In a parallel circuit, the path of least resistance will carry the majority of the current as evidenced by your video. You are drawing over 100 amps out of the battery in your video but that current is flowing through an 8 ga wire. If the 12 ga fusible link fails, the 100+ amps will, then, be diverted through the factory wire and instantly blow the factory fusible link, or in this case, your 20 amp fuse in the video.

 

[72RoadrunnerGTX]

In a parallel circuit, the path of least resistance will carry the majority of the current as evidenced by your video. You are drawing over 100 amps out of the battery in your video but that current is flowing through an 8 ga wire. If the 12 ga fusible link fails, the 100+ amps will, then, be diverted through the factory wire and instantly blow the factory fusible link, or in this case, your 20 amp fuse in the video.

Ok, and? Does not matter which leg carries more current or has less resistance. Doesn’t not matter which fusible link opens first. What matters is how much total current flows before any circuit protection reacts and will any segments of conductors in any part of the newly created parallel circuit be able to safely handle the combined current being allowed to flow by the paralleled fusible links. In this case, the carbon pile load is connected to the battery bus on the fuse box for this demonstration, routing from there to splice 1 on a single 12ga wire, from splice 1, with the shunt wire in place, there are now two paths to the battery, one through the ammeter and out to the battery via one set of Packards (12ga wires) and the stock fusible link and another path out the alternator feed (12ga wires), through another set of Packards to the alternator stud then on to the battery through the shunt wire and its fusible. Yes, the shunt wire will have less voltage drop, doesn’t matter which leg has the least resistance from the alternator post, total current flowing to the point of a short anywhere in the stock wiring far exceeds the ampacity of any stock 12 ga wiring with the fusible link shunted. If you look carefully, it was actually 130+ amps before the 20amp circuit protection trips in the demo. That’s not enough to burn 12ga wires? How much current would you say will light up 12ga wiring?

According to Powermaster, circuit protection on the shunt wire is optional, there are others who promote this shunt wire with no circuit protection at all, a full-sized battery cable directly from a battery terminal to the alternator.

I think I’m done with this thread now, pretty clear I’m not getting anywhere here. Have a fire extinguisher handy always, shorts happen.

 

[Nacho-RT74]

Crank it over and the engine goes into high idle once it starts and that 120+ amps that the alternator is capable of pumping out goes THROUGH the ammeter to that battery that is sucking it through the 60-rated ammeter and, thus, turning it into a fuse.

I will read this post carefully later along with the consequent replies by Doug, but this statement got me somehow stunned., so had to reply to this specific first.

When you have been a battery requesting 120 amps to be recharged? You can’t speed up the recharge process just because the alt is able to provide it. So the ammeter won’t get that either.

Plus: even less if the 120 amps doesn’t provide that current at iddle (nor at fast iddle when warming engine)

With my 80 amps Mopar alt even revving up just the firts 1 or 2 minutes I have got max ammeter charge reading starting from a jumped flat battery. Then begins to decrease still revving up the engine.

IMHO, the battery recharge process has its own speed by its own internal chemical process and can’t be speeded up no matter the recharge capacity from the alt.

Just asking, not being critic… and sharing what I have experienced at least.

What I made is not correct either because from a flat batt the right procedure is recharge it out of the car, HOWEVER in an emergency this situation can be saved and I got a trick to save the emergency… charge the batt on car with headlights on (and even some other accs like blower). This will save some of the load being requested by the full system sensed by the regulator will be out of the ammeter. Although the batt will take more time to be recharged.

Of course just works safe yet if the firewall paths has been upgraded/saved, specially the alt path to the cab.

Once again, is my own experience based on real world personal situations I have been. It was no my imagination but a real personal experienced situation.

P.S.: in case of this emergency, having a 8 gauge jumper wire on trunk to run it temporarily between alt and batt could be good idea. To save this emerge on the road.