Diagram how to save the the volt gauge on b body 71

[bobfist]

Hi!

Just got all wireharness for my 71 b body
But i read somewhere that it is possible to have the voltage cables not running thru the bulkhead so i dont melt the new one and volt meter
Any diagram how to do that?

[Pete in NH]

Bob,

If you have a 1971 Factory service manual, look for the 65 amp Leece-Neville Alternator installation in a Coronet or Satellite. That will show how the factory did it. It was called the "Fleet By-pass" modification. Many B bodies back then were used as police cars and taxis and had the big alternator to power the radios.


Or, you can run a new #8 black wire from the alternator output stud through a hole with a rubber grommet in the firewall near the bulkhead connector directly to the ammeter stud with the black wire on it. Then you cut the original #12 black wire from the alternator off at the bulk head connector pin. On the other side of the ammeter you run a new #8 red wire through the same grommet to the 5/16" stud on the starter relay through a new fusible link or 50 amp Maxi-Fuse and holder.

[bobfist]

WOULD I SEE THE AMPS ON THE GAUGE THEN?

[Pete in NH]

Yes, the ammeter still show current going into or out of the battery. All this change does is keep the current from flowing through the bulk head connector pins which were handling more current at times than they could do so safely.

Chrysler realized with the bigger 65 amp alternator the connector pins would be way over their limit. But, this is not a bad change to make even with smaller alternators. 

[bobfist]

Thanks

I have every harness new so i dont know if its nessesery but want to
Know how to do it anyway. The car also have the electronic system with volt reg etc but that dosent save me anyway if something goes wrong?

[Nacho-RT74]

http://www.dodgecharger.com/forum/index.php/topic,33574.0/all.html

[bobfist]

Thanks!

[Nacho-RT74]

Chrysler realized with the bigger 65 amp alternator the connector pins would be way over their limit. But, this is not a bad change to make even with smaller alternators. 

Actually as I post on the thread, with smaller alts could be even more important!

[71 SE3834V]

Ok Pete & Nacho, I read another idea/way of bypassing was to just run an 8 or 10 ga. wire from the alternator stud to the starter relay stud with a fusible link or fuse. The electricity would chose the path of least resistance and would flow through the new larger wire instead of the old which is smaller and would have resistance at the bulkhead terminals due to age/corrosion etc. Of course your alt. gauge would no longer work or just move a small amount.
Your opinions on this?

I have all new wiring forward of the firewall and time and effort being a killer for me this would be an easier solution. I will be hooking up a voltage gauge and I don't ever plan on having any more than the stock accessories installed, well unless you count the draw from the lights on the 3 aux gauges. Heck the radio doesn't work and there is no plan in the works to remedy that. 

[Pete in NH]

Hi Jeff,

Yes, you could do that. Don't run the new wire directly to the starter relay stud though, even with a second fuse or fusible link. Join the new wire with the old red wire ahead of the fuse or fusible link so that both wire paths go through the same link of fuse. As you say the ammeter will not longer read correctly.

If you were to use two fusible links in parallel paths you could potentially get up to twice the current through the system. It's likely one link would blow and then the other but, things could get a bit hot in the wiring before that happened.

[71 SE3834V]

Yeah I thought that as soon as you said it.
The only thing is I have a real hard time cutting into my new wire harness. Part of the reason I don't have plans to upgrade my ignition.

When I replaced the harness I cleaned the terminals at the bulkhead. Under the dash there is evidence of some overheating as a couple of wires have just enough melting to make them stick together. As far as my electrical use, I only turn on the heat blower once in a while for testing purposes, rarely drive it at night using the headlights, have never driven in the rain yet so wipers aren't use so I figure at this time my risk is low.

[Pete in NH]

Jeff,

On my 71 the red wire from the ammeter ends in a single wire connector that the fusible link plugs into. The other end of the fusible link goes to a 5/16" ring terminal on the starter relay stud. You shouldn't have to cut into your new wiring harnesses.

[Nacho-RT74]

Making run that wire is like join together batt and alt, and both sharing same power source allmost as an only one electrical source, and both sourcing the car through both terminals at bulkhead at the same time.

The only hard job on run wires to ammeter is make the hole on firewall, that's all... Then as stated ALTHOUGHT initially my thread shows dual fuse link, is better as Pete says, only use one fuse link... I updated that info on same thread on last replies. Was a learning procedure.

No need to cut anything. You could make a small piece of wire between existing red wire and fuse link with male and female terminals to fit in the middle, where will splice the new wire.

[71 SE3834V]

Jeff,

On my 71 the red wire from the ammeter ends in a single wire connector that the fusible link plugs into. The other end of the fusible link goes to a 5/16" ring terminal on the starter relay stud. You shouldn't have to cut into your new wiring harnesses.

I guess that would be pretty easy! I don't have my car home yet so I didn't have it here to reference.

Making run that wire is like join together batt and alt, and both sharing same power source allmost as an only one electrical source, and both sourcing the car through both terminals at bulkhead at the same time.

The only hard job on run wires to ammeter is make the hole on firewall, that's all... Then as stated ALTHOUGHT initially my thread shows dual fuse link, is better as Pete says, only use one fuse link... I updated that info on same thread on last replies. Was a learning procedure.

No need to cut anything. You could make a small piece of wire between existing red wire and fuse link with male and female terminals to fit in the middle, where will splice the new wire.

I think I understand what you're saying Nacho. Here's my understanding of what would happen.
Basically the full power of the Alt. would go to the battery.
The needs of the cars electrical system would feed through the bulkhead from the relay stud but it would be much less amperage than what is needed to charge the battery after starting therefore much less risk. The highest draw would be if and when you had everything on (lights, heater, wipers, etc.) at the same time.
How's my theory? (I did have electrical theory but that was 35 yrs ago.  )

Bare in mind when I talk about difficultly I'm not talking about my ability to do it. I'm talking about how hard it is physically on me. Wiring has gotten difficult for me lately with the arthritic hands and anything under the dash is terrible with my back. I realize that the best way to work behind the dash would be to pull the cluster.

[Nacho-RT74]

The full power of the alt, won't go to the battery if the battery doesn't need it. The full power of the alt will be spliced through both paths, the existant one and the one spliced into the starter relay, then going to the cab LIKE if it was coming from the batt and the alt at the same time. But the batt side will be providing the less due the ammeter resistance.

Same when engine is not running. The power from batt will be going through both paths, the existant one and the added wire to the alt stud, then into the cab through the existant alt wire, but once again, the less from the batt side, due the ammeter resistance

Which is true, is when the batt gets discharged, the full power won't go into the cab and throught the bulkhead

[71 SE3834V]

If the battery doesn't need recharged then doesn't the regulator cut back on the alt. output? Through testing I have seen my truck alternator go from minimal amp output to full amp output when using my snowplow.

The amperage output of the alt wouldn't be split equally between the 2 wires if you used a larger gauge wire than the existing one as the larger the wire the less resistance it has therefore you will get more amps through the larger wire.
The original design was bad enough but you add in the corrosion in the connections (mostly at the bulkhead) and you have added more resistance the the equation. The alternator is trying to push the same amperage through a connection that now has more resistance in it and the result is heat.

[Nacho-RT74]

if the batt doesn't need to be recharged, the regulator cuts the power just enough to keep the car working. Hence on a correct wired ammeter, the needle should stay death centered. No power coming or going to the batt through the ammeter, just alt sourcing the car demands.

remember the missconception from factory about the ammeter, saying is an alt gauge where is really a BATT gauge. The alternator will never discharge since is not an acumulator, so how an ammeter can be an alt gauge with a DISCHARGE rate reading ?

the amperage output will be spliced "equal", true, but with more conections allong the line, more resistance, and the power coming from batt will find more resistance due the ammeter from that side to feed the main splice which is on alt side of ammeter.

You'll find the ammeter needle will barelly move, ( if really moves ) with the jumper wire. What do you think will mean ?

[Nacho-RT74]

The original design was bad enough but you add in the corrosion in the connections (mostly at the bulkhead) and you have added more resistance the the equation. The alternator is trying to push the same amperage through a connection that now has more resistance in it and the result is heat.

the original design got the main fail actually on low alt capacities, specially at iddle... THEN after that the bulkhead terminals being weak and prone to fail due the enviroments. Then they came out with the wires straight through the firewall with bigger and better terminals before the firewall.



Note, I'm not saying the jumper wire between alt and batt ( starter relay stud ) won't work... just saying will not work like everybody thinks

[Nacho-RT74]

If the battery doesn't need recharged then doesn't the regulator cut back on the alt. output? Through testing I have seen my truck alternator go from minimal amp output to full amp output when using my snowplow.

from where is being sourced the snowplow ? battery?

if you are sourcing it from battery ( what is what I think ) then of course the ammeter will give you CHARGE reading but doesn't mean actually is charging the batt, just means the load is going through ammeter to the batt side to feed the snowplow ( or any accesory you incorrectly source on batt, power plants to stereos etc.. ). That is an added stress allways has happened on our cars, when incorrectly sourcing the extra accesories from batt instead from alt.

an ammeter won't say you YOU ARE SOURCING THE SNOWPLOW, is saying THE LOAD IS GOING TO THE BATT "charging it"... then you have to think... do I have something sucking the power on batt side aside the batt itself to get really a charge reading being the batt is actually charged ?

[71 SE3834V]

If the battery doesn't need recharged then doesn't the regulator cut back on the alt. output? Through testing I have seen my truck alternator go from minimal amp output to full amp output when using my snowplow.

from where is being sourced the snowplow ? battery?

if you are sourcing it from battery ( what is what I think ) then of course the ammeter will give you CHARGE reading but doesn't mean actually is charging the batt, just means the load is going through ammeter to the batt side to feed the snowplow ( or any accesory you incorrectly source on batt, power plants to stereos etc.. ). That is an added stress allways has happened on our cars, when incorrectly sourcing the extra accesories from batt instead from alt.

an ammeter won't say you YOU ARE SOURCING THE SNOWPLOW, is saying THE LOAD IS GOING TO THE BATT "charging it"... then you have to think... do I have something sucking the power on batt side aside the batt itself to get really a charge reading being the batt is actually charged ?

Your misunderstand my setup mostly because it's very hard to explain things w/o seeing them.

When I said I got a high reading from a gauge it was NOT a dash gauge but an ampmeter hooked inline to the alt to test the output.
You cannot connect a snowplow motor to the alt. or source it to the alt. It requires battery sized cables and the alt will not put out enough power. I think my alt is a 150 amp. The snowplow motor is the size off a starter motor and will draw high amps to use. We used to install 2 batteries run parallel to run the plows because you are constantly using the battery to work the plow and if you only used 1 battery it would be run down in a couple of years. This was back many years ago when alternators were only 100-110 amp. Since the larger alternators are now available the batteries last longer because the alt can keep the charge up.

[71 SE3834V]

THEN after that the bulkhead terminals being weak and prone to fail due the enviroments.

If you lived in this area w/the salt usage in the winter then you might think differently about the corrosion issue. It's a HUGE problem with older vehicles. I've owned many snowplow trucks over 30 years and corroding wires were a constant problem up until they started sealing the connections.

[71 SE3834V]

if the batt doesn't need to be recharged, the regulator cuts the power just enough to keep the car working. Hence on a correct wired ammeter, the needle should stay death centered. No power coming or going to the batt through the ammeter, just alt sourcing the car demands.

remember the missconception from factory about the ammeter, saying is an alt gauge where is really a BATT gauge. The alternator will never discharge since is not an acumulator, so how an ammeter can be an alt gauge with a DISCHARGE rate reading ?

the amperage output will be spliced "equal", true, but with more conections allong the line, more resistance, and the power coming from batt will find more resistance due the ammeter from that side to feed the main splice which is on alt side of ammeter.

You'll find the ammeter needle will barelly move, ( if really moves ) with the jumper wire. What do you think will mean ?

I fully understood your post on the bypass conversion when I read it a while back.

Paragraph #1 above:
I fully understood that. I have a pretty good understanding of 12v electricity. I have been formally trained and have worked with it for decades though not everyday.

Paragraph #2:
The gauge is neither an alt gauge nor a battery gauge. It is an ampmeter gauge or a "movement of amperage" gauge showing in which direction electricity is moving. Either from the battery (discharge) or to the battery (charging).

Paragraph #3:
I didn't know the main splice was on the alt side of gauge. That WILL play a part in resistance but how much. If battery charging amperage is eliminated how much is left to run through the original wiring and gauge? The lights and blower would be your largest draw. Could the original system handle that plus whats needed to run the car? If you don't use the blower and rarely the lights I would think your risk would be much lower.
I think ultimately your bypass would be the best way to go but running an 8 gauge wire spliced to the fusible link would be a quick fix to lower your risk until the better fix is performed.

Paragragh #4:
If main splice is on the alt side of gauge then gauge would most likely show a discharge all the time since the cars needs are moving from the battery through the gauge to the main splice. How much? I don't know. It might be important if you are selling the car to show everything is working correctly but I could live w/it since I will have a volt meter/gauge installed.

[Nacho-RT74]

#2
the ammeter shows what you say, true, but in relation with batt . Rest of system can work, getting loads here and there and if ammeter doesn't registry any activity, it means the batt is quite resting without provide any load to source anything on the car and the alt is providing everything. Thats what I say about getting a good alternator will save your ammeter.

#3
is shown on the diagrams on my thread. ALL the loads are taking from alt side of ammeter, no one on batt side ( but starter motor which load is never registered by ammeter... too much for it )

#4
if gauge shows discharge being main splice on alt side, it means the alt power is not enough to fill the car demand, then the batt begins to provide what alt is not able to give. So is true, will show a discharge reading on THAT moment. BUT if alt is enough to feed the car demand, the ammeter won't read anything. All the load play is out of the ammeter reading... EXCEPT if BATT is ALSO requesting load to fill it back untill its chemical balance is made ( fully charged )

[Nacho-RT74]

THEN after that the bulkhead terminals being weak and prone to fail due the enviroments.

If you lived in this area w/the salt usage in the winter then you might think differently about the corrosion issue. It's a HUGE problem with older vehicles. I've owned many snowplow trucks over 30 years and corroding wires were a constant problem up until they started sealing the connections.

don't worry, we have same enviroments conditions down here LOL... excepte salt useage due the winter, but close to the coast, and salt is around in the air

[Nacho-RT74]

If the battery doesn't need recharged then doesn't the regulator cut back on the alt. output? Through testing I have seen my truck alternator go from minimal amp output to full amp output when using my snowplow.

from where is being sourced the snowplow ? battery?

if you are sourcing it from battery ( what is what I think ) then of course the ammeter will give you CHARGE reading but doesn't mean actually is charging the batt, just means the load is going through ammeter to the batt side to feed the snowplow ( or any accesory you incorrectly source on batt, power plants to stereos etc.. ). That is an added stress allways has happened on our cars, when incorrectly sourcing the extra accesories from batt instead from alt.

an ammeter won't say you YOU ARE SOURCING THE SNOWPLOW, is saying THE LOAD IS GOING TO THE BATT "charging it"... then you have to think... do I have something sucking the power on batt side aside the batt itself to get really a charge reading being the batt is actually charged ?

Your misunderstand my setup mostly because it's very hard to explain things w/o seeing them.

When I said I got a high reading from a gauge it was NOT a dash gauge but an ampmeter hooked inline to the alt to test the output.
You cannot connect a snowplow motor to the alt. or source it to the alt. It requires battery sized cables and the alt will not put out enough power. I think my alt is a 150 amp. The snowplow motor is the size off a starter motor and will draw high amps to use. We used to install 2 batteries run parallel to run the plows because you are constantly using the battery to work the plow and if you only used 1 battery it would be run down in a couple of years. This was back many years ago when alternators were only 100-110 amp. Since the larger alternators are now available the batteries last longer because the alt can keep the charge up.

yes is true, I don't have in mind how you are connecting or how you have wired the snowplow into the truck... will be great you shown me

however... is more less the same the alt is providing what snowplow is sucking. In line Ammeter is registring that load requested by the snowplow... but if you turn off the snowplow, the SAME alt at SAME RPMs with SAME ammeter, will get you smaller to 0 reading, because there is nothing sucking power, no matter if alt is still spinning the same.

would need to know how you have wired everything to tell you exactly what is happening thought

alt provides what car needs ( devices, batt ) if there is nothing demanding power, alt ( of course, managed by the regulator ) won't send anything. Ammeter will register what batt is getting or providing, but if fully charged, nothing will go or come from it, so ammeter will read 0... everything will be playing into the alt side without ammeter play.