Without getting into every detail to bore you here goes. I started my daytona up this year and noticed the amp gauge showing a slight discharge.
I took the alternator and a new(but years on a shelf) spare Ive had for years to get tested. Napa said both were bad, Autozone said my original was bad and the spare was good.
Soooo, I put the spare on and got the same result of a slight discharge. When I had the car running and disconnected the battery ground cable the car would stop running. So I ordered a new Volt. Reg.from FBO because my car was converted to a Pertronix elec. ignition.
I put the new regulator on and the spare Alt and all was good. Also put the original alt. (that was supposeldy bad) back on and the gauge read just fine. Took the car out for a drive, did a burnout across an intersection and hit a bump which made me go from first to third. Now I noticed the gauge was back to a slight discharge!! Mother F@$#^R
So I ordered another Volt Regulator and an ignition module just in case. Put them in and the gauge was reading fine-actually it was pretty far to the + side. Let it idle just fine. Revved the engine a couple time and it went to slightly discharge again!!!
So explain this. I tried both alternators in my 63 Valiant Convertible - BOTH indicate everything is charging according to the gauge but when I disconnect the battery on the original the car shuts off ----when i disconnect the battery when I have the spare Alt on it will keep running--- but when I do the same thing, with the same Alt on the daytona, the daytona shuts off. I'm stumped and pissed-- I HATE electrical shit. Building a house is easier
Any time the ammeter is on the discharge side it means the car is consuming more power than the charging system is supplying; this could be because the charging system isn't working correctly or because something in the electrical system is consuming a lot of power, more than the properly operating system can supply. A short circuit anywhere in the electrical system could be the cause of the high power consumption.
Have you inspected the bulkhead connector? Bad connection/ high resistance could be causing it.
you should never disconnect a battery cable while the engine is running. The electronics in the alternator, regulator, and ignition systems do not like it....test your system properly with a volt meter and an ammeter hooked in series with a battery cable