The dreaded “ticking time bomb” factory Ammeter

[RJRENTON]

Amperes ( based on a volt rate ) is what makes the car ( or anything, not just car ) to work, not volts by itself. You can get 120 volts to feed your garage bulb the same than 120 volts to feed your welding machine... but both use diff amperage to work. If you don't have the amperes source and the paths ( conector and wires allong with the breaker ) able to feed the welding machine, simply won't work or maybe will burn something around, but the bulb will light up without problems... and both still are 120 volts

What does the forgoing statment have to do with the subject....answer: NOTHING. PERHAPS this guy needs to be introduced to, as I've said before, OHM'S LAW. Or maybe Kirchhoff's circuit laws, which deal with addition aspects of Ohms Law that pertain to individual parts of a circuit and current flow.......or not...
BOB RENTON

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Kirchhoff's circuit laws are two equalities that deal with the current and potential difference in the lumped element model of electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of James Clerk Maxwell. Wikipedia

 

[Don Frelier]

English is not his first language. I think the point he's trying to convey is that automobiles take varying amounts of current but the voltage remains constant.
Let's try and be generous with our comments.

 

[RJRENTON]

English is not his first language. I think the point he's trying to convey is that automobiles take varying amounts of current but the voltage remains constant.
Let's try and be generous with our comments.

I realize that English is not his first language.....but....inaccuracies in the comments and the interpretation of the issues MAY direct others down the wrong path. Perhaps a little education in some of the electrical concepts and theories of how things work might be beneficial.....maybe, the old addage of "a little knowledge can be a dangerous thing" could apply....?? ....from one engineer to another.....
BOB RENTON

 

[Builderguy]

Might want to slow your roll there BOB, insulting someone is no way to try and make a point. It only turns people off to what you are trying to say. Speaking of which I see you use a lot of drawings and formulas that are well know. What you are lacking is a simple diagram done by YOU (like the numerous ones done by by Nacho) that answer the question posted. Nacho has provided several ways to bypass the ammeter and still get a reading. If someone wants to use his advise fine; if not, fine too. But it is far past time for this thread to end.

 

[Nacho-RT74]

Don't worry guys, I'm used to this kind of situations.

The problem is I have noticed most of the times he doesn't pay attention on my post and the reasons for it, but just search for some small inaccuracies of them ( which is true some can get some technical inaccuracies ). Just noticed it on a recent thread where OP was asking about the blue constant voltage MP regulator along the thread and he thought we were talking about the blue ign circuit. And that is just an example of many.

After read some small discussion he got with 72RoadrunnerGTX about the Ammeter function being a battery gauge or not, just noticed this disagreement is a regular situation.

About the specific quote he made we can make another straight experiment on our cars similar to the post he quoted

We maybe have a 120 amps cranking power capacity batt, which maybe is 700 or 800 amps reserve load battery. With the same battery you feed your starter motor able to suck anything between 80-120 amps on a 2 gauge wire, you also feed a fender/hood turn signal lamp which maybe sucks 1/4 of amp with a 18 gauge wire. Both on same 12v nominal rate, but a diff amperage level and wiring is accordingly to the device to be sourced, not the power plant where is connected. The lamp won't burnt being sourced from the same power plant than the starter motor...being both of course designed to work on same nominal voltage rate.

And based on this continuing with the thread, you can install a 120, 150 amps alternator, but if your car sucks just 30 amps average, the alternator will source just that juice. If you have a discharged batt, will suck maybe 20-30 amps more on an initial stance ( we can't push in more amps because battery won't charge faster it's able to get charged on its own chemical process ). What's the deal with this? Just get the paths ready to hold this stage, the 30-40 amps the car will suck on its normal operation, plus the 20-30 amps the batt will suck to get recharged ( which will be going down while is getting recharged BTW ). That makes 50-70 amps.

How many amps will go throught the ammeter? Just the 20-30 amps to recharge the batt, not the 50-70 amps the alt feeds! That is just if the car and accesories are correctly wired and in good conditions. Nothing being sourced from batt or starter relay stud as a tipical junction points being used since ever ( wrong proceeding on ammeter cars ).

The ammeter just reads what comes/goes to the batt, not the full car load. But the alternator path to the ammeter will get the full load for both. An not even the section between the main splice and the ammeter neither the wire between amm and starter relay stud! Mainly just the wire between alt and main splice!! But since we are upgrading wiring actually doesn't hurt to upgrade both ammeter paths.

The only moment the ammeter will take the full car load is on an unnoperative alternator ( completelly damaged or not spinning ), registering discharge of course.

The deal with bigger capacity alts is just warranty the full capacity to source the system including a discharged batt at any engine speed, keeping the batt out of the game the most as posible. Normally an alt is able to feed ( based on specs around we can read ) 40-60% of its max output at iddle speed. So a 120 amps alternator will be on 50-70 amps capacity while iddling.

However with just 40-60 amps alternator capacity at iddle, your battery will NEVER ( or barelly, depending on car options and actual alt capacity ) get discharged on regular situations, so your ammeter will be peacefully at 0 reading 85-90% of the time. 0 reading means no load going throught the ammeter. No Load, no heat. No heat, everything safe and happy, and just need to be sure about the paths capacities to the cab.

 

[Triple Black 73]

Here's the deal. You guys are missing the context.

This all got started way back when because I recommended the best way to install a large alternator and large battery would be to completely by-pass the ammeter. And that started a $#!+ storm from old timers that think ammeters are the best thing since sliced bread.

Yet, they fail to understand the whys: Why they were ever used in the first place. Why they are bad to use with big alternators and batteries. And why zero modern cars use them.

But I'm the knuckle head running 160+ amps load on my '73 Charger without issue? okay.

 

[Hemirunner]

I vote that we start a few more ammeter threads... lol

 

[70chall440]

I think that a large part of this problem is the majority of people do not understand electrical systems in general and to be honest Ma Mopar didn't make it any easier with the way they wired these cars. So if you are coming from a place of misunderstanding or a lack of understanding, it can be a challenge to understand how these systems function especially when you start to make changes. On top of this, the internet is full of misleading and at times incorrect information. Lastly, people who do understand the systems tend not to be good teachers (no offense meant to any one here), while they know what they are talking about, sometimes it they do not convey their thoughts or message well which to someone who doesn't understand in the first place makes it even more confusing.

None of us were born with this knowledge and all of us are still learning, I know for a fact that I learn something new pretty much every day and find that things I "thought" I knew were in fact wrong.

As it relates to the amp meter, I can only say that since it is rated at 35 amps, if you are running a charging system higher than that (most probably are) then it makes sense that it cannot or should not be used as it only presents a potential problem. Personally, I merely disconnect the 2 wires and join them ensuring that they are well isolated from any thing could ground them. On all of my larger builds, I completely rewire the car with a new harness which never has a provision for a amp meter.

 

[Triple Black 73]

As it relates to the amp meter, I can only say that since it is rated at 35 amps, if you are running a charging system higher than that (most probably are) then it makes sense that it cannot or should not be used as it only presents a potential problem.

Thank you. Someone finally agrees with me!

I rewired the heck out of my car for the EFI upgrade. Even wired the headlights as a ground trigger. That was a fun little project to figure out! Not much is left of the original Year One engine harness. I have a 220 AMP alternator that runs directly to a 1000 CCA battery. Never had cleaner power in that old car!

My normal running load is over 100 amps (without audio system) and most of it it goes to an Eaton 8 relay/fuse waterproof box mounted inside the left fender. That box powers the ECU, fuel pump, CDI ignition, 2x big fans, and the headlights. The last circuit will power PS and oil coolers with auto temp fans.

 

[Ranger16]

I vote that we start a few more ammeter threads... lol

And by the way, what's the "best oil" to use in my ammeter?

 

[Nacho-RT74]

You really are not understanding how it works. And if with all the threads posted explaining with every detail as posible, diagrams included you still don't understand, nothing will do.

UNTILL you experience it by yourself.

Sorry, it can't be explained more simple that has been posted ( aside maybe some language barrier at least on my side )

of course everything gets its limits, but making everything correctly you won't have anything to worry.

 

[Nacho-RT74]

On a side note. Of course a 100 amps load won't be hold nicelly by the ammeter, but this load would read by the amm just when engine is off as a discharge ( once again, if correctly sourced )... which shouldn't be of course, because the correct is being sourced with engine running on most of these loads added

 

[72RoadrunnerGTX]

since it is rated at 35 amps

Curious where the “rating” you speak of is published, where have you seen that. In all this “Old-timers” experience, I’ve have never seen a listed rating for these ammeters anywhere, including factory docs from the time at the dealers. I’ve seen a few different variations of scaling, but all have the same basic internal design that can handle much more than 35 amps without issue.
Reminder, this thread, and some others here on this subject, was intended to be about ammeters in a stock, or somewhat stock, configuration and the false myths and misinformation propagated by some of the whippersnappers in this hobby.

 

[RJRENTON]

Some respondents to the issue of amp meters, automotive electrical distribution systems and the fundamental parameters of Ohm's law and Kirchoff's laws, should, at least, become aware of these fundamentals before venturing an opinion or a recommendation based on their redoubtable expertise (?) .....
I agree with the premise of ending this and associated threads dealing with issue......as it's been beaten to death as the subject of: best oil, best coolant, should i use a 160 degree thermostat, best wax, best spark plugs, or beer....
BOB RENTON

 

[70chall440]

Curious where the “rating” you speak of is published, where have you seen that. In all this “Old-timers” experience, I’ve have never seen a listed rating for these ammeters anywhere, including factory docs from the time at the dealers. I’ve seen a few different variations of scaling, but all have the same basic internal design that can handle much more than 35 amps without issue.
Reminder, this thread, and some others here on this subject, was intended to be about ammeters in a stock, or somewhat stock, configuration and the false myths and misinformation propagated by some of the whippersnappers in this hobby.

I will be honest, I pulled the 35 amps from this thread and from what I have heard over the years. I readily admit that I do not have a source or intimate knowledge of the actual figure. I am not necessarily an amp gauge hater but it seems when this subject comes up there is always someone who says "so long as the terminals are clean..." which is probably true but as I see it, why leave something that "could" become an issue for no good reason other than it came that way. I will say this, I have dug into quite a few vintage Mopars and it is very rare to find one that doesn't show some evidence of melting or overheating at the amp gauge. That coupled with the pretty much uselessness of the gauge itself convinces me to deactivate it.

Hey if you like it and want it, then you should have it. I would say that Mopar did have up to 120A alternators in cars that had amp gauges so I guess they determined it was fine up to that amount at least.

 

[72RoadrunnerGTX]

As I posted before, "Ammeters are only useless to those who don’t understand completely the information they provide as it relates to the original charging system function. Admittedly, this would include likely 99% of the owners of these cars then and now."

Will add one more point then will let this thread go, I’ve never seen connection/insulator issues on any ammeters in cars that clearly haven’t been messed with after leaving the factory, even to this day. Heat issues at the connections are the result of being over tightened or left loose by some previous cluster servicing in my experience.

 

[Nacho-RT74]

Curious where the “rating” you speak of is published, where have you seen that. In all this “Old-timers” experience, I’ve have never seen a listed rating for these ammeters anywhere, including factory docs from the time at the dealers. I’ve seen a few different variations of scaling, but all have the same basic internal design that can handle much more than 35 amps without issue.

Agreed, and even better if reinforced, just the full scale won't be read due the calibration by itself, and as any path with incorrect wire gauge section for 100 amps, it gets its own limits where the heat becomes on the issue due the section resistance to that load BUT, a batt will never suck 100 amps to be recharged ( amps can't be pushed in, battery gets its own charging speed based on chemical process ), AND as mentioned hundred of times if correctly sourced, all upgrades will "should" work with engine running to the alt source that load, and not the batt with engine off which could be the ONLY instant the ammeter could get that load ( and on a damaged alt/reg stage )

Reminder, this thread, and some others here on this subject, was intended to be about ammeters in a stock, or somewhat stock, configuration and the false myths and misinformation propagated by some of the whippersnappers in this hobby.

THIS IS the point. Ppl who advise instantly to bypass the ammeter like a red flag spring loaded waiting to be triggered anxiously without consider the real situation first. Is simply an automatic response without any previous analysis from ppl who don't even understand the charging system.

Make the corrections and experimenting how the corrections make the difference to personally check how the corrections really works is SOOOOO SIMPLE!!!, but nobody cares really and goes into the "fast" solution. Most of the times is like run to replace the engine where the failure it was just the gas pump or a clogged gas filter.

 

[Nacho-RT74]

Some respondents to the issue of amp meters, automotive electrical distribution systems and the fundamental parameters of Ohm's law and Kirchoff's laws, should, at least, become aware of these fundamentals before venturing an opinion or a recommendation based on their redoubtable expertise (?) .....
I agree with the premise of ending this and associated threads dealing with issue......as it's been beaten to death as the subject of: best oil, best coolant, should i use a 160 degree thermostat, best wax, best spark plugs, or beer....
BOB RENTON

Bob, yes, everything on the theorical is great and as I thanked you on the PM you sent me once, I give you the thanks here too ( taking aside the post with a non precisely respectful opinion ), BUT I'm talking from the experience making the setup on my own DRIVER car and watching the results daily of every change, upgrade and full operation of my car electrical system. AND the tech service bulletins and master tech conference lit/vids where our statements are supported on how the ammeter on our car works and what really means its reading.

If just MaMopar made a correct alternator selection with more output from factory ( giving a correct output rate at iddle ), and considered these loads on most of our cars to the bulkhead paths, this was never become on an issue. Or not at least on the same grade like it became.

The low rated alt was a mistake from factory or it was due lack of technology for better alts back in the 60/70s? Or a combination of both? Dunno.

On a side note, I would be even more gratefulll if you actually read my posts before any claim or response where not just once, but several times has been clearly noticeable you don't read completelly my posts or where is my response going

 

[Triple Black 73]

@72RoadrunnerGTX

You're still pushing the idea that people who don't like ammeter are just dumb? What an ***.

 

[Triple Black 73]

THIS IS the point. Ppl who advise instantly to bypass the ammeter like a red flag spring loaded waiting to be triggered anxiously without consider the real situation first. Is simply an automatic response without any previous analysis from ppl who don't even understand the charging system.

Why is it always agree or you're just dumb?

Maybe some people (like the entire automotive industry) understand exactly how the old charging system work and realized its not ideal. Maybe they realized (about 40 years ago) that an ammeter has no place in a vehicle. Maybe smart folks figured the best thing to do is wire the alternator directly to the battery, then battery to the rest of electrical system.

Nope. It's because we don't understand an electrical system designed for 35 amps. And the issues we have is only related to bad connectors & loose terminals. Certainly not designed limits of that ancient charging system and small wire designed to only carry the current it was rated for. No sir... Just a failure of understanding....