Ammeter to Voltmeter Conversion -- Existing Wire Question

[Nacho-RT74]

If you are adding that kind of stuff, consider an alt able to provide all the power as posible at the less RPMs as posible... this means Iddle. Then also upgrade the wiring accordingly.

You should make this KEEPING OR NOT the ammeter. The battery is just a reserve load capacity and crank up power source, but everything on car must be matched with a correct alternator for everything. However, trust on me and some others who already made it around you can keep the stock ammeter still with all those accesories as far everything is correctly hooked up, works on the correct stages and be sure about and ammeter check inside for a good conditions gauge and related isolators. Remember our cars have been abused for 50 years and electrcal system is the more dismissed area of the car when talking about abuses.

 

[RJRENTON]

The above analogies are largely incorrect. Consider the national power utility grid, where everything is interconnected and the age of the grid, which is reported and purported to be "in poor health due to its age". Yet, everyday, it continues to supply all the energy the consumers require. How is this possible, you ask? How can an aging supply system continue to supply the need? The "secret" is due in large part to the DIVERSITY FACTOR. if the utilities were to design the grid to supply 100% of all connected loads (energy required) 100% of the time, the system (the grid) would need to be several orders of magnitude larger (200x - 300x larger) than it is now. The DIVERSITY FACTOR is a factor that decreases the DEMAND, not the total connected loads on time; usually, this factor is approximately 15% - 20% of total connected load, thereby reducing the amount of power (energy) the grid must supply. When peak demands exceed available capacity, the utilities apply (turn on) "peaking stations", which are independent natural gas powered turbine generators, that supply the momentary/short term demand.
The same thing applies to the vehicle and its "ageing wiring and connections". The supposition, as stated by the previous comment, assumes that 100% of the vehicles requirements are needed to be supplied 100% of the time. Again, this assumes no diversity, and the energy source (alternator) must supply all requirements and the starting battery is used strictly for starting. The battery can an does, seamless, supply the DIFFERENCES IN LOAD between what is connected and what is needed (diversity factor). When the excess demand passes, the existing alternator will recharge the battery. Batteries have two ratings: cold cranking amps (starting) and a specified AMP HOUR rating which, stated how much power can be extracted over a given time period (say 20 amps/hr for a given number of hours) before reaching a specified terminal voltage (10.5 volts). It is this reserve capacity is what allows the variations in the diversity factor of the connected loads.
If the vehicles innitial charging and delivery system were designed to supply 100% of the connected loads 100% of the time, it would be 2x -3x larger than installed. Now, it seems that a large percentage of people want to add power consuming devices to their cars, such as the new cars have: EFI, electric fuel pumps, electric cooling fans, sound systems, aux lighting, heated seats, A/C, heated glass, etc. Yes, to this end, the charging and delivery system MUST BE DESIGNED to accomodate the demand.....not arbitrarily changing things based on supposition or hearsay or "guesses". If the existing system is changed, the changes contemplated need to be based on sound engineering principles and standards. Just my opinion of course.
BOB RENTON

 

[Nacho-RT74]

as mentioned on one of my previous replies... I was to be dismissed on my post. Not a problem... I'm used to that. Guys, just make your own experiments and make your own decision based on the practical world

 

[mrmolding]

as mentioned on one of my previous replies... I was to be dismissed on my post. Not a problem... I'm used to that. Guys, just make your own experiments and make your own decision based on the practical world

No worries. I appreciate your help and understood your comment! For now I'm going all new M&H wires and bone stock. By the time I started driving these they were 15 years old and I drove them for another 9 years with almost no wiring issues whatsoever. My 68 GTX kept blowing ballast resistors and a shop in Springfield, VA figured it out but it was unknown to me what they did. I think nowadays I'd grab my multimeter and start checking everything. So, since I'm starting over it should be a time machine/reset on the car. Right? I've only upgraded the shocks and torsion bars. Everything else is stock even the motor and tranny rebuild from the PO in 2012. I took an electronics class in high school and that's about my level of knowledge. If I decide I want to do anything additional I'll keep plowing through the posts, but every response in here helps greatly! I don't know all of the disciplines to properly build and run these things, so I love all of the feedback and just reading posts. In the old days, you had to understand motors and how to debug a car when it would not run or overheat and that was about the extent of it. So for now, I'll just remain a stock parts replacer. But when I need to upgrade or add something new, eventually something gels after reading lots of posts, and I start down that path. Thanks again and thanks to everyone who responded!

 

[Rebel74]

So... is the issue the full current running through the 50 year old dirty and unmaintained ammeter? OR is it the full current running through 50 year old crapped-out connections at the bulkhead disconnect? Or both?

So that if you cleaned the electrical up, perhaps replace the connections at the bulkhead with wire running direct through using grommets, and clean or if necessary replace the ammeter and its connections, and make sure all your wiring/fuses match whatever loads you expect to be drawing, then you should be good to go?

 

[hunt2elk]

So... is the issue the full current running through the 50 year old dirty and unmaintained ammeter? OR is it the full current running through 50 year old crapped-out connections at the bulkhead disconnect? Or both?

So that if you cleaned the electrical up, perhaps replace the connections at the bulkhead with wire running direct through using grommets, and clean or if necessary replace the ammeter and its connections, and make sure all your wiring/fuses match whatever loads you expect to be drawing, then you should be good to go?

Biggest issue is the big red and black wires going through the bulkhead terminals to the ammeter. Those terminals really aren't great for high amp loads. When they get loose or the connection is compromised, that causes more heat, leading to a meltdown or fire. Really, if you don't have any non factory high load accessories and keep those 2 connections clean and tight as well as the connections on the ammeter in the same condition, you should be fine.
I personally eliminate the bulkhead connections as well as the ammeter just for piece of mind. My Grandpas 1970 Satellite which he bought new, burned up from a dash fire in 1985. Of coarse the bulkhead and ammeter connections were never maintained on that car, it is always stuck in the back of my mind.

 

[72RoadrunnerGTX]

So that if you cleaned the electrical up, perhaps replace the connections at the bulkhead with wire running direct through using grommets, and clean or if necessary replace the ammeter and its connections, and make sure all your wiring/fuses match whatever loads you expect to be drawing, then you should be good to go?

At the risk of repeating previous posts here, by far the weakest link in the original design, as far as longevity is concerned, is the use of underrated and unsealed terminations in the charge circuit at the bulkhead connector, in an effort to reduce initial assembly time. These terminations have been failing at high rate since these cars were new. At a minimum, bypass both bulkhead terminations with a direct wire runs to the ammeter. Details above I’m sure.

Yes, as with any other systems on a 50-year-old car, some maintenance is required. Wiring, connections, insulators and added aftermarket load points should be checked, issues corrected. Any electrical system can/will fail if abused and neglected.

 

[Dave6T4]

At the risk of repeating previous posts here, by far the weakest link in the original design, as far as longevity is concerned, is the use of underrated and unsealed terminations in the charge circuit at the bulkhead connector, in an effort to reduce initial assembly time. These terminations have been failing at high rate since these cars were new. At a minimum, bypass both bulkhead terminations with a direct wire runs to the ammeter. Details above I’m sure.

Yes, as with any other systems on a 50-year-old car, some maintenance is required. Wiring, connections, insulators and added aftermarket load points should be checked, issues corrected. Any electrical system can/will fail if abused and neglected.

As I discovered while helping a friend with his '62 Dart, 1962 and 1963 Dodge's had buss bars that passed through the firewall block that the red and black wires bolted to. It is too bad that Chrysler did not continue this arrangement.

 

[72RoadrunnerGTX]

As I discovered while helping a friend with his '62 Dart, 1962 and 1963 Dodge's had buss bars that passed through the firewall block that the red and black wires bolted to. It is too bad that Chrysler did not continue this arrangement.

Yes, screw terminals are a more reliable higher current connection in high moisture environments but do require more time to assemble. The “click-together” Bulkhead connector change likely shaved off a minute or two per car on the assembly line. That and the fact that nothing about these cars was ever designed to last more a few years.

 

[mrmolding]

After I created this thread, I had a change of heart and decided to find out what happens when you do a total reset of electrical and keep the car stock just to cruise around in. I started driving these when they were about 10 years old and I did experience electrical issues with my 68 GTX in 83 or so. I had to take it to a specialty shop to fix it.
So, I decided to get new or repop everything to replace all electrical -- all new M&H harnesses, new light pigtails, ignition switch, etc. The only thing I did not put in were NOS like the turn signal switch and some heater control switch wiring. All gauges are repop OER (might be a huge mistake, but we shall see). Took me 4 months on weekends and I'm still finishing up power steering and interior. I will update in a few months if this was a massive failure and I'll run my dash down to Red Line to get the voltmeter conversion and put in Crackedback's charge wire. I guess I really want to see if resetting everything and keeping it stock with current replacement components will be sufficient.
Just got the steering column painted, reassembled, and ready to go back in the car. Someday I'll get a proper bench and not makeshift saw horses, bubble wrap, and bungee cords to keep it steady and protect it while I'm working.

 

[Nacho-RT74]

Get an alt able to handle the car loads at iddle to complete the job. They use to be rated at 90-100 amps output to feed around its 60% capacity at iddle... if not, you'll be resetting to the initial status with their original fail included. With an alt able to feed the car load demands, even the bulkhead Which is the weakest point will be able to survive, because they will never get the car loads PLUS the batt recharge load since the batt will never or barelly demand for charge load.

How is that?
If your car usually needs 35-40 amps to operate with their accesories, that will be what the alt will feed. If the batt gets discharged, this will add 15-25 amps to the car load ( depending on the batt discharge rate and alt speed ) this mean the black wire coming from alt will feed anything between 50-65 amps. Here is when the bulkhead ON BLACK WIRE becomes the dangerous point. Keeping the batt out of the game because you have a good alt, will keep this extra charge load also out of the game.

And never feed anything from batt or starter relay posts.

 

[mrmolding]

Get an alt able to handle the car loads at iddle to complete the job. They use to be rated at 90-100 amps output to feed around its 60% capacity at iddle... if not, you'll be resetting to the initial status with their original fail included. With an alt able to feed the car load demands, even the bulkhead Which is the weakest point will be able to survive, because they will never get the car loads PLUS the batt recharge load since the batt will never or barelly demand for charge load.

How is that?
If your car usually needs 35-40 amps to operate with their accesories, that will be what the alt will feed. If the batt gets discharged, this will add 15-25 amps to the car load ( depending on the batt discharge rate and alt speed ) this mean the black wire coming from alt will feed anything between 50-65 amps. Here is when the bulkhead ON BLACK WIRE becomes the dangerous point. Keeping the batt out of the game because you have a good alt, will keep this extra charge load also out of the game.

And never feed anything from batt or starter relay posts.

Thanks! Actually, if I am going to be using all stock, do you recommend a specific alternator? I know it only draws what it needs, but the only thing that I have not yet replaced in the alternator in the car.

 

[Nacho-RT74]

As mentioned, any alt rated at at least 90-100 amps. Several brands around I can't guarantee. I'm personally toward to TuffStuff which I'll get when the money for it comes, but there are some other options around too like Powermaster, dB Electrics... Some other will tell you newer units like Nippondenso.

 

[mrmolding]

As mentioned, any alt rated at at least 90-100 amps. Several brands around I can't guarantee. I'm personally toward to TuffStuff which I'll get when the money for it comes, but there are some other options around too like Powermaster, dB Electrics... Some other will tell you newer units like Nippondenso.

Great! Thanks again for all of the help!

 

[zyzzyx]

While I have no experience whatsoever about recommending an alternator, I'm leaning towards
a Nippondenso that is internally regulated. Two birds with one rock! Very dependable, and charge
at idle RPM. Just my .02

 

[Nacho-RT74]

As far I know/recall there are some Nippondenso units externally regulated, so would be somehow a plug and play job.

However the other three mentioned are stock look. Specially TuffStuff. Powermaster and DB Electric use the revised later squareback unit. TuffStuff uses as far I know earliers squareback units which in case to be used with mech regs ( pre 70 ) will require ground one of the brushes

 

[Rebel74]

Do I understand correctly that if I were to install a modern internally regulated alternator I can do away with the voltage regulator on the firewall? I would just need to keep the regulator under the dash that manages the instrument gauges (5 volts, if I remember correctly)?

 

[Jeff Erwin]

Do I understand correctly that if I were to install a modern internally regulated alternator I can do away with the voltage regulator on the firewall? I would just need to keep the regulator under the dash that manages the instrument gauges (5 volts, if I remember correctly)?

You are correct. I kept my voltage regulator on the firewall just so it looks right but the wires aren't connected to anything.

 

[Don67Satellite]

Our C-Body brethren have a thread or 2 on this going as well. This guy has an interesting approach for an "under hood bypass" to remove 50% of the load from the ammeter circuit. He also spells out a full bypass later in the thread for those that were wanting that.

https://www.forcbodiesonly.com/mopar-forum/threads/underhood-ammeter-bypass.55911/

Direct link for his "Simple Bulkhead Bypass"

https://www.forcbodiesonly.com/mopar-forum/threads/simple-bulkhead-bypass.56391/

 

[mrmolding]

So I keep forgetting to ask this — if you have a lower output alternator say 45-60 amps vs 90 or higher, does the lower alternator prevent too much current/overload? Basically I understand a higher output amp will power only as much as you need but does a lower amp alternator prevent too much load to keep in line with original wiring requirements?