After Market Ammeter?

nm9stheham said:

FWIW... the later plastic ammeters were a lot worse to fail than the earlier ones. And harness/connection failures take place separately from the ammeters, so that is confusing issues. Ammeter aren't worthless if you know how to read them; voltmeters don't tell you everything either.

Regardless, Coalman is getting good help and advice.

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so, what do you need to know that a voltmeter won't tell you?

First thing that comes to mind is that an ammeter will tell you if the battery is consistently pulling a charge and providing current when needed (like at low RPM's with the headlights on, which is a usable indicator of battery health. A VM can't do that.

In some cases, both take some skilled interpretation of possible causes, like if you have a blown diode so neither has any real advantage there.

For most folks, what a VM says is simpler, and so takes less interpretation.

What do you think happens to a voltmeter when the battery is providing the charge with the engine running?

It will read far below the normal charging state the alternator provides.

Watts, volts and amps are ALL interconnected and the ammeter is still a worthless gauge that can burn up your car...

crackedback said:

What do you think happens to a voltmeter when the battery is providing the charge with the engine running?

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Yes, it shows a lower voltage..... which does not actually tell you that any current is flowing out of the battery. It only says the system's voltage is lower, and nothing about the battery's contribution and operation in that situation.

Not all ammeters are bad ju-ju; ammeters are fine if good and wired right. Piper and Cessna light aircraft came with them for several decades. No general issues with them, none at all; the ammeter is still in my '61 Cherokee and there were never any AD's on the ammeters. It has to stay there because there are no STC's to allow it to be removed. They were built better and the wiring was done right. And the early Mopar ammeters were indeed constructed differently. The later ones are surely suspect with their age; but none of the 5 new A/F bodies and 3 new C bodies that my family had when I was growing up ever had a hint of ammeter issues, both plastic and pre-plastic designs.

As I have the instrument cluster out and most of the wiring in work, I thought of installing an extra 4 place ganged glass fuse holder tapped off the run side of the ignition switch. Any suggestions on where to tap in and anything else related would be appreciated. Thanks a bunch

the entire problem with all (at least U.S.) ammeters is that "car makers are cheap." The "full current" Mopars were a problem, and the "improved" external shunt ones, whether GM, Ford, or Mopar were sometimes "numb" meaning, they were way too unresponsive. this is because the manufacturers all did exactly the same thing.........used the actual wiring harness for the shunt for the system. This created an ammeter which could barely "tell" if the headlights were on or off!!