Ammeter gauge shows slight discharge

[rms492]

Hello, I have a '70 Dart, and recently, I noticed the ammeter is showing a slight discharge whenever I have any electrical stuff on...such as brake lights when stopped, the ammeter shows a discharge. I put the A/C on, and a much bigger discharge. Once I accelerate, the ammeter stays right in the middle.

It used to be not like this, it would always slow a slight charge.

I just changed the voltage regulator to a new one from YearOne...could that be the cause? Does that need to be grounded correctly to the firewall? maybe I didn't tighten the two bolts firmly enough to the firewall?

thanks

 

[Bad Sport]

Try cleaning up the spot where it's bolted on.

 

[Bulldozer]

read this thread
http://www.forabodiesonly.com/mopar/showthread.php?t=173673

 

[67Dart273]

Discharge at low speeds can be from a few causes

First, you may have an "early" so called "roundback" alternator. The later so called "square back" ones are better at low RPM

Second, there might be a bad diode, etc, which dimishes the output power of the alternator

If someone has done some performance mods, you might have "underdrive" pulleys, common for drag and other racing, which slow down the alternator And don't discount that the belt may be marginal, as well

Third, wiring problems such as "the usual suspects" the bulkhead connector, etc, can aggravate the symptoms

Last, Up to a certain point, "that's how it is" with stock Mopars. Frankly, back in the day, most people just went on with their lives and "it was fine." You really have to ask yourself "just how much time do I spend idling?"

The alternator below was originally a 69/ earlier "grounded field" roundback. This is one that a rebuilder has actually MODIFIED (see the hole at top) to install a second brush to convert it for use on a 70/ later vehicle. STAY AWAY

The FACTORY roundbacks for 70/ later were also used, but also charged poorly at low RPM

Below is a later "squareback" which comes ONLY in isolated field. However you can use them with 69/ earlier regulators by grounding one field terminal. These are the ones you want for better low RPM charging

The bottom photo is out of a 70 shop manual. This was the original "isolated field" so it is NOT a rebuilder modified 69/ earlier. It has two legitimate factory isolated brushes. These also are less desirable for low RPM