ammeter / voltmeter

If you read the causes will understand. The fail you got IS NOT because the ammeter. Not at least per the ammeter by itself, but some other parts underrated ( being the alt as the first underrated device )

STOP blamming the ammeter ( which is not the real cause ) if you don't understand how it works the system.

Take a look at the diagram:


Check out the long path that the charging current has to go through to reach the battery. To me, this seems like a real bass-ackward way to design a system. This also places a fluctuating current into everything inside. Even when new, it seems to me that this was not optimal. Add 40-50 years of time and corrosion and those two intersections where power enters and leaves the bulkhead get corroded and burn.

Now, while this diagram is an improvement, I did my car a little different. These guys just "looped" the ammeter wiring and sent it back through to the fusible link. I eliminated the wire they show as RED. My power feed is a larger 10 gauge.
No more of this:

KD have you ever read my thread at DC.com ?

Rusty 72 said:

everyone should make it a priority to bypass that amp gauge.

Click to expand...

Couldn’t disagree more with this blanket statement. Research the facts and address the real causes.

Information overload in that thread.
What I caught in summary is that in pure stock form with no corrosion and tight connections, the ammeter is fine. This is one perspective.
Another is...Dump the ammeter, reroute the alternator wiring to allow a direct path to the battery rather than into the interior through tiny spade connectors and install a voltmeter.
In my Charger, I added an entirely new gauge cluster that had a voltmeter.
In my Power Wagon, I just did the bypass and the MAD conversion similar to what I posted in post # 22. I added a voltmeter there.
Same with the '72 Duster that I just finished today.
What is the drawback to bypassing the ammeter? A non stock appearance?

Well I did say just my $0.02.
I'm not claiming to be an expert by any means. I do know that the failure and near fire for me (thank god it didn't happen) was on the path that the Amp gauge was on. Seeing that you have a large voltage funneled through a gauge that I'm sure wasn't anywhere near a 10 gauge wire, it makes sense to me to remove it.
As far as the OP, it seems they were having trouble with original wiring and possibly that gauge, so since it isn't needed it makes sense to me again to suggest they bypass it.

because you are being simple... IT SEEMS... but is not.

when ppl gets a carb trouble, fix or replace the carb after work hard and find the problem IS ACTUALLY the carb. You don't replace the carb if the problem is the gas pump... well it is more less the same. Locate the problem and then blame the real reason, not what IT SEEMS to be the reason.

You can bypass the ammeter but the low charge problem will persist.

KD, anybody can make anything it wants but as far is based on the correct understanding of the system and not simply because it reads everywhere the ammeter "is the problem" which IS NOT the problem. It could BECOME on a problem if get some other problems around. But guess what? nobody cares untill is late. Nobody pays attention on a consistent discharge reading or a constant swap back and forth reading of the ammeter untill is late! Everybody despites the electricity system mantenience and or correct upgrades on it simply because never consider how important is. Electrical system is same important than the gas lines, your brakes or add more power to the engine! You change your TC if you change the Camshaft... but nobody change the alt or check the wiring when changing to a bigger capacity batt

as we could read, the ammeter gave a consistent reading on discharge side and the voltimeter gave 14 volts reading. So, if you didn't have the ammeter you could think everything is fine, but it wasn't.

I totally agree with you that the charging system deserves its due respect just as any other system and very much so gets overlooked.
I was one of those that was quick to allow shoddy work on my part in the past. This 72 Charger had already been damaged when I purchased it non running. The previous owner said "the Alt wire had burned up". Upon inspection it was so much worse.
After having to rewire the entire car I am certainly going to take another look at other project vehicles I have as well.

And a HUGE mistake made due the unknownledgement of how the charging system works with an ammeter is EVERYBODY sourcing all added accesories on batt post. This accelerated the burning and overload process of the system, including of course the ammeter. Then still blame the ammeter when once again IS NOT, but the IDIOT wiring the new accesories ( mech or owner ).

Ammeter cars must get accesories sourced from alt side of the charging system. Alt post, or some buss in the middle of the line between amm and alt, just like factory made.

Between amm and batt it must be NOTHING.

JUST STARTER RELAY to feed the starter motor is in the middle because that big load must be out of the ammeter ASIDE is a temporally load. Then the ammeter will sense the charge process after the load lost while cranking. But feed anything else with constant loads like stereo plants, headlights upgrades, etc... is a BIG mistake. And EVERYBODY makes that!

Just some temporally loads could be sourced from batt side of the ammeter ( factory made that also on some models for power windows ).

And of course, acc added ---> alt ( and wiring ) must be upgraded accordingly... but once again nobody made it and BOOM once again, ammeter blame LOL

OE went to a voltmeter not because it is better but cheaper to install

Kern Dog said:

Take a look at the diagram:

View attachment 847600
Check out the long path that the charging current has to go through to reach the battery. To me, this seems like a real bass-ackward way to design a system. This also places a fluctuating current into everything inside. Even when new, it seems to me that this was not optimal. Add 40-50 years of time and corrosion and those two intersections where power enters and leaves the bulkhead get corroded and burn.
View attachment 847601
Now, while this diagram is an improvement, I did my car a little different. These guys just "looped" the ammeter wiring and sent it back through to the fusible link. I eliminated the wire they show as RED. My power feed is a larger 10 gauge.
No more of this:

View attachment 847603

Click to expand...

One thing to also remember is yes its a longer path for the alt to charge the battery but its a short path for the alt to supply all the units on the car that the alt needs to supply when the car is running. With a good charged battery most of the amps are flowing the shorter path supplying everything on in the car. And only a small amount of about 5 amps or so will need to flow to a good charged battery to keep it up.

In the bottom pic with the alt output going to the starter relay the amps flow is now farther to supply all the loads in the car. Both can have advantages depending on if its stock amp gauge wiring of if its been modified and changed to a by passed amp gauge and a voltmeter. Ron

Not sure I’m following, are you saying the length of conductors in the charging circuit effects the charging or load current flow on a healthy original design?

I also rewired my 67 a bit differently too. It was the fastest and easiest way I came up with, without drilling new wires through the firewall.