BYPASS the AMMETER? (1969 A12)

[747mopar]

I've had around 20 mopars over the years, worked on way more than that.
I can only recall replacing 2 alternators, never had a belt fly off.

Good for you.... not sure what your point was.

ammeter was eliminated because wasn't cost effective. Is so true than even on laters 80s and 90s models there was not even voltimeters but just an idiot light ( to make it even cheaper ). Need to say they changed to a shunted ammeter system on 75 ( 76 on A bodies ) which is a more expensive than the full load ammeter. In fact, M bodies got the shunted ammeter with a circuit board and an extra voltage test light.

You can be disagree all that you want, But I'm able to proove the ammeter is the best way to know the actual status of the charging system and how to run it safe. But that will work just if you care. If you don't care to learn about it, then won't be the way to show that, no matter what I'm able to say.

I won't argue that point. For me it's a matter of preference, I like seeing the state of my battery vs amps, obviously if the volts are dropping your in trouble but at least you know where you are.

 

[Don Frelier]

Good for you.... not sure what your point was

My point was that you indicated these were reasons to switch to a voltmeter. I'm saying they are so rare or nonexistent they don't support the reasoning.

 

[747mopar]

My point was that you indicated these were reasons to switch to a voltmeter. I'm saying they are so rare or nonexistent they don't support the reasoning.

I indicated that I "personally" like Voltmeter's because you can see the state of your battery and threw in a few examples. No I don't throw belts, I have had it happen during a burn out, I've had a power steering pump lock up which smoked the belt, **** happens. It's like anything else, all preference, no wrong answer as long as things are done correctly. I've had both, both are useful tools, voltmeter's just tell me what I want to know.

 

[Don Frelier]

I have both on my charger. I find the ammeter more useful. It has electric fans and with the array of taillights the voltage will drop to 12volts at a light with the brakes on. Now if you put a voltmeter on a non running car and it read 12 volts it would need a charge. yet in this instance the battery would actually be almost fully charged I just have a high load at idle which is set pretty low around 625 rpm.

 

[RM23M9A]

So, I ask Year One's guru regarding using the harness HU199BM (Elect Ign Modified). He tells me.....

"Note that the engine harness, like the original harness, is not wired to support alternators rated higher than 55 amps. If an alternator rated above 55 amp is desired you will need to add a heavier charge wire. Also, adding the charge wire will result in current bypassing the ammeter, reducing the indicator needle movement. You may want to add a voltmeter or other device to monitor the charging system function".

Here's the tag or sticker from alternator been in my car for 3 years... Could THIS have caused a Ammeter wire to fail?

 

[72RoadrunnerGTX]

A higher output rated alternator, on its own, won’t cause wiring to overheat. Excessive current burns wires, you need a short or other over-load condition to melt wires. That said, when up-sizing the alternator, the charge circuit wiring needs to be up-sized as well to handle the potential alternator output current as determined by the current total vehicle running loads.

The M&H reproductions are just that, copies of the original harnesses, including undersized charge circuit wires running through the bulkhead connectors, the real weakness in the design. I unwrap them, replace the 12ga charge circuit wires with 8ga marine grade wires routed around the bulkhead connector, through a firewall grommet, directly to the ammeter (as the factory did on their later fleet vehicles with larger alternators). Likewise, the charge circuit run to the starter relay in the forward lighting harness. The fusible link will need to be up-sized as well.

End result; a factory appearing harnesses that can handle any and all modern loads I want, a fully functional ammeter, providing way more info than a simple voltmeter.

 

[RM23M9A]

A higher output rated alternator, on its own, won’t cause wiring to overheat. Excessive current burns wires, you need a short or other over-load condition to melt wires. That said, when up-sizing the alternator, the charge circuit wiring needs to be up-sized as well to handle the potential alternator output current as determined by the current total vehicle running loads.

The M&H reproductions are just that, copies of the original harnesses, including undersized charge circuit wires running through the bulkhead connectors, the real weakness in the design. I unwrap them, replace the 12ga charge circuit wires with 8ga marine grade wires routed around the bulkhead connector, through a firewall grommet, directly to the ammeter (as the factory did on their later fleet vehicles with larger alternators). Likewise, the charge circuit run to the starter relay in the forward lighting harness. The fusible link will need to be up-sized as well.

End result; a factory appearing harnesses that can handle any and all modern loads I want, a fully functional ammeter, providing way more info than a simple voltmeter.

Wow, makes perfect sense now. Seems like the RED 12Ga Ammeter wire is a little "wimpy". Unable to find exactly what amperage a factory Alternator did put out, I really have no choice. Seeing lot of owners going to 90 amp alternators and 4 Ga wiring. But these same people running electric fuel pumps, fans and stereos. None of which I intend to ever use. It sucks that I guess since using Electronic Ignition now, really have no choice. As reading the diagrams shows, the black feed off the Ammeter is main source to everything else behind the firewall.. This should be fun..

Thanks!!

 

[72RoadrunnerGTX]

BTW, On the charge circuit bulkhead by-pass described, if you are not adding loads to the dash harness, it is not necessary to modify any wiring in the dash harness. Leave the black harness ammeter lead on the ammeter to feed the factory splice, disconnect and tape back the red lead.

60amp max output alternator, A12 car, absolutely no loads other than factory stock, no A/C added, no headlight upgrades? I’d have no problem running the reproduction harness as is with one exception, by-pass the bulkhead connections on the charge circuit, both directions.

 

[RM23M9A]

The RED charging wire you modified, runs directly from ALT Output I'm thinking?

Cant seem to rely on the diagrams any longer. A12's must have been different, the colors more closely resemble .a 69 Dart!

 

[72RoadrunnerGTX]

Yes, That’s a ’72 Rallye cluster. Layout is a bit different but basic charging system color coding is the same. Those are 8ga wires.

Ok, forget that picture and comments relating to wire size upgrades for your current scenario, a bone stock electrical system replacement, no added loads. On a ’69, with new engine and dash harness, I would remove the 12ga black charge circuit wire/Packard connector from the bulkhead connector (firewall side), cut and carefully splice an extension lead, route it through the firewall to the ammeter black side stud, leave the dash harness black lead in place. I believe the ’69 has the fusible link connecting directly into the bulkhead connector on the firewall side. I’d remove its Packard connector from the bulkhead connector and splice an extension lead to it, routing to the ammeter red side stud directly, again the existing dash harness red lead can stay put. It’s the Packard connectors that create the most trouble over time.

 

[72RoadrunnerGTX]

The red ammeter lead runs to the battery via the bulkhead connector/fusible link connected to the starter relay.

If you are not up-sizing the entire charge circuit wire run, the extension leads can be 12 ga as well, nothing gained by short lengths of larger wire. I'd use 10 ga for the extensions, good soldered splices, shrink tubing, good quality grommet.

Yes, your old bulkhead charge circuit connections burned up from excessive resistance and resulting heat at the Packard connectors.

 

[RM23M9A]

What IF, I use a 55 AMP single grove pulley Alternator?!!

No wiring work needed?
Just reconfiguring alternator brackets I suppose?

 

[Nacho-RT74]

Ok several notes because I still can see lot of stuff is not clear.

The alt just will put out whatever load the car requires as far is able to. Your car is what sucks 30, 40 or 50 amps, so the wiring must be matched to the loads it requires, NO MATTER the alt you have. The amperes are not pushed in by the alt but sucked out by car. If the alt doesn't have the capacity, the batt will be sucked out. But still will demand same load.

The problem with stock alts is they are really poor at iddle and low speeds, which depending in your driving or city, could be the most time spends ( traffic, rain ) so it keeps sucking from batt, then you give gas, and alt has to supply per battery demand, the load lost while alt was not capable. What I said the trick on this? If your car sucks a constant 30, 40, 50 amps loads then keep the batt out of the game sucking more amps... 30 amps becomes maybe in 45, 40 amps becomes on 53, 50 amps becomes on 64 amps... these extra 15, 13, 14 amps are the one being sucked by the batt to get recharged again then this will be the load going through the ammeter as a Charge reading.

While the batt is charged, the load supplied by the alt will be JUST for the car, right on the splice between ammeter and bulkhead on black wire. It won't be running anymore to batt and ammeter won't get any load going throught, zero reading. no load it means no heat. This is the ideal status.

The batt is just like a baby! Will be sucking milk while is hungry! When is not hungry, won't suck anymore!

Sure it will be load running throught the bulkhead, SPECIALLY on black wire, not so much on red wire ( same reason, batt is full, and won't be running load to that side ) so, the bulkhead bypass will save this loads. It can be done on several ways. 72RoadrunnerGTX chosen just forgett the bulkhead path and keep exclusively the bulkhead bypass. Myself I preffer to keep the bulkhead path and get an extra one being parallel. Why? Because in that way the main splice, which is in the middle between ammeter and bulkhead, will keep being sourced from both sides, the wire between splice and ammeter, and the wire between splice and bulkhead. This means the splice is being feeded by 2 12 gauge wires. Using just one path, the one bypassing the bulkhead despiting the stock one running throught the bulkhead, even if you use an 8 gauge wire, the main splice is still being feed by just 1 12 wire, the existant one between ammeter and splice. Sure you still will be safer to feed the batt when required with this, but IMHO you can keep doubled the sourced to the main splice keeping the stock one.

72RoadrunnerGTX is using what it was done from factory on earlier cars and later upgraded at dealers, but on laters factory setup with high load cars the bulkhead path was kept in place, adding the extra path without despite the bulkhead one. 73/74 diagrams show keep the bulkhead path still using the extra one.


Is true stock ammeter are designed to work. On +/-40 amp range, so it won't hold 50, 60, 90 amps, but ONCE AGAIN, the alternator will never put 90 amps, because your car will never suck 90 amps on normal conditions. The deal with 90, 130 amps is get the best iddle capacity ( 40, 50 amps ) to keep the batt out of the game, hence the ammeter too.

ASIDE THIS, You can't speed up the charge on batt even having a 400 amps alternator! Batteries gets it own chemical process to be recharged and you can't push it up. Once again, as a baby, it will get its own speed to suck the milk! in NORMAL conditions, a discharged batt can suck maybe 30 amps for 3 or 5 minutes, but once this initial process began, it will be into 10-20 amps untill is fully charged. The more charged, the less load will be sucking and you'll see this load through the ammeter. So you will see THIS LOAD going through the ammeter on its reading, not the full 90 or 130 amps from alt

 

[RM23M9A]

Ok several notes because I still can see lot of stuff is not clear.

The alt just will put out whatever load the car requires as far is able to. Your car is what sucks 30, 40 or 50 amps, so the wiring must be matched to the loads it requires, NO MATTER the alt you have. The amperes are not pushed in by the alt but sucked out by car. If the alt doesn't have the capacity, the batt will be sucked out. But still will demand same load.

The problem with stock alts is they are really poor at iddle and low speeds, which depending in your driving or city, could be the most time spends ( traffic, rain ) so it keeps sucking from batt, then you give gas, and alt has to supply per battery demand, the load lost while alt was not capable. What I said the trick on this? If your car sucks a constant 30, 40, 50 amps loads then keep the batt out of the game sucking more amps... 30 amps becomes maybe in 45, 40 amps becomes on 53, 50 amps becomes on 64 amps... these extra 15, 13, 14 amps are the one being sucked by the batt to get recharged again then this will be the load going through the ammeter as a Charge reading.

While the batt is charged, the load supplied by the alt will be JUST for the car, right on the splice between ammeter and bulkhead on black wire. It won't be running anymore to batt and ammeter won't get any load going throught, zero reading. no load it means no heat. This is the ideal status.

The batt is just like a baby! Will be sucking milk while is hungry! When is not hungry, won't suck anymore!

Sure it will be load running throught the bulkhead, SPECIALLY on black wire, not so much on red wire ( same reason, batt is full, and won't be running load to that side ) so, the bulkhead bypass will save this loads. It can be done on several ways. 72RoadrunnerGTX chosen just forgett the bulkhead path and keep exclusively the bulkhead bypass. Myself I preffer to keep the bulkhead path and get an extra one being parallel. Why? Because in that way the main splice, which is in the middle between ammeter and bulkhead, will keep being sourced from both sides, the wire between splice and ammeter, and the wire between splice and bulkhead. This means the splice is being feeded by 2 12 gauge wires. Using just one path, the one bypassing the bulkhead despising the stock one running throught the bulkhead, even if you use an 8 gauge wire, the main splice is still being feed by just 1 12 wire, the one between ammeter and splice. Sure you still will be safer to feed the batt when required with this, but IMHO you can keep doubled the sourced to the main splice keeping the stock one

72RoadrunnerGTX is using what it was done from factory on earlier cars, but on laters the bulkhead path was kept in place, adding the extra path without despite the bulkhead one. 73/74 diagrams show this.


Is true stock ammeter are designed to work. On +/-40 amp range, so it won't hold 50, 60, 90 amps, but ONCE AGAIN, the alternator will never put 90 amps, because your car will never suck 90 amps. The deal with 90, 130 amps is get the best iddle capacity ( 40, 50 amps ) to keep the batt out of the game, hence the ammeter too.

You can't speed up the charge on batt even having a 400 amps alternator! Batteries gets it own chemical process to be recharged and you can't push it up. Once again, as a baby, it will get its own speed to suck the milk! in NORMAL conditions, a discharged batt can suck maybe 30 amps for 3 or 5 minutes, but once this initial process began, it will be into 10-20 amps untill is fully charged. The more charged, the less load will be sucking and you'll see this load through the ammeter. So you will see THIS LOAD going through the ammeter on its reading, not the full 90 or 130 amps from alt

Ahhh, I see! So going BACK to a 55 amp alternator really wont help at all?
Wow

 

[RM23M9A]

Man, what a pain in the butt!
LoL.. So best advice? Stick with the 60 amp I have?

 

[RM23M9A]

If I could find a DIAGRAM on how someone did this, be so much easier...

Thank.You!!

 

[Nacho-RT74]

Ahhh, I see! So going BACK to a 55 amp alternator really wont help at all?
Wow
View attachment 979115

I was to quote this before the later reply LOL.

a 55 amps alt is sure an improvement over a 50 or 45 older amps, but will still feed 25/30 amps iddling as max output. At day light and no traffic is quite enough BUT As soon you are in traffic, let's say at night, press brakes, headlights on and even worst, RAINING ( wipers on ) you'll see your ammeter going down to discharge, headlights will dimmout, wipers going slower. Wipers by them self sucks around 10-12 amps! You can check that with engine off and turn them on. The ammeter will register that load coming out from the batt!

You don't have AC but got heater I guess. The blower is the problem with them, not th AC by itself. blower sucks also 8-15 amps depending on speed selected. Sure AC adds a problem because compressor reduces the engine speed, which also makes slow down the alt, getting less juice, but blower sucks the same on both

The alternator decal you posted shows 81 amps as max output and 41 at 2000 ALTERNATOR RPMs. That is maybe 35-38 amps at 750-800 RPMs engine.

 

[Nacho-RT74]

If I could find a DIAGRAM on how someone did this, be so much easier...

Thank.You!!

Sure is was made... ON THE TREAD I POSTED AT DODGECHARGER.COM!!! lol.

Several updates made along the years, so check it all.

 

[RM23M9A]

Yep. Its still on car, was putting out 15.05V at idle..
Thought maybe thats too much? Especially at idle!

Seemed to run fine with it until i got this burnt up.ECU problem. Decided to just replace all the wiring. It was fried.

 

[Nacho-RT74]

15 volts is not necesarilly a charge status! It could be a regulator deal, or even a malfunction alt. Once I had 18 volts and discharge on ammeter. Alternator was shorting while spinning ( one of the stator leads making friction with one of the rotor vent vanes wile spinning ). This caused a voltage spike, but a load lack. Still with 18 volts I unplugged batt and engine stalled.

Volts can burn stuff but never will melt anything. Volts doesn't cause heat! Amperes does.

High Volts rate can go througth a hair thick wire, amperes not.