My alternator gauge is acting strange in my 68 Charger R/T. At idle it is 0 to slightly minus, but recently it is going all the way to plus 40 when it get over 1500 rpm.
Every piece of wiring in the car is new Year one harnesses. I have the solid state voltage regulator that is in the original looking 68 style caseing. Alternator has 3 connections and it has a chrome ignition box, all which are new. What do I check first? Car runs fine and starts right up after driving it.

I'll give you a for this one... maybe the question here should be: How "should" the factory in-dash amp gauge be reading under normal driving conditions? I would say mine is:

In gear, stopped, foot on brake, headlights on = Reads about -20 on the gauge

In park, idling, no headlights = Reads just slightly to the "-" side

Cruising at a constant speed, lights on or off = Reads maybe up to +20 on the gauge

Under heavy acceleration, it will sometimes jump up above +20 but just for short temporary bursts. I'd like to hear from others about how their gauge behaves.

Darren

What an ammeter does depends on a few things:

The charge on the battery

The amount of load, like lights, heater, A/C

The RPM of the engine.

When you start a car, say in the spring, when you don't need heat or A/C, and get out on the blvd and cruise for a few miles, it should not take long for the meter to "zero" when cruising at a steady speed. At speed, say you turn on the A/C. The meter might jump a little, but it should go right back to center.

Now, here you are at the "red light." The engine is idling slowly, maybe you've got both the lights and the A/C running, so there's lots of load. The alternator cannot keep up, so the meter goes negative some amount.

If you rev the engine a little, or go through the light, the meter should charge again, for a little while, until it gets the battery "caught up."

Some good indicators of problems IN THE LONG RUN are things like wild fluctuations, dim or really bright lights, odor from the battery, or worse, damage to the cables and paint around the battery.

Of course if you let the dreaded smoke out, that's still another story.

The other problem with ammeters, is, it turns out all these late '60's and early '70's cars had a poor design, namely the wire size was marginal, the firewall connector is a problem, and the ammeter connections can get hot, loose, and fail.

Also, when you start rewireing them, you can end up with loads--like accessory lamps, or even things being re-wired--you can end up with loads on the "wrong side" of the ammeter, electrically. This will cause the ammeter to give you erroneous readings.


My problem is, I really like ammeters, but more and more, as I read the posts on these forums, I realize what a pain they've become.

charging and wiring upgrades

this topic was wrote by me... English is not my mother language so I hope will be good enough

GO to this web site and it will answer all your questions on your alter. gauge issues. And tell you how to fix them. Trust me we went throught 5 cars with this problem and corrected them all.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

I defeated the ammeter and bulkhead connection in my car by performing the following steps:

1st-the original connection to/from the starter relay was disconnected and taped back.

2nd-the original connection to the ammeter "input" stud was disconnected and taped back.

3rd-a 12gauge wire (with a 16gauge fuse-link) was run from the starter relay to the alternator stud.

4th-a 12gauge wire (with a 16 gauge fuse-link) was run from the starter relay to the ammeter "output" stud through a grommet in the firewall.

Doing this will eliminate the ammeter's function and questionable bulkhead connections. It will also give 2 paths for current to flow to the factory "weld splice" (a.k.a. the ammeter's "output" stud) which is the main power feed to the entire vehicle.

Seems like a better idea to me!

Dan

If it just started, (1)VR lost it's ground or(2) batt has a bad cell. or(3) corroded connections somewhere.