Ok, b4 I installed new alternator, the old alternator the indash Amp Meter would constantly discharge, and the voltmeter would range 13-14 volts!!
Not sure where voltmeter wires r connected, was in car when I bought it,
You may be dealing with a wiring hack. 13 to 14 Volts is about right for operating voltage. It may go down a little at slow idle, especially with lights on.
Yes, all readings at idle, tried to identical under dash voltmeter and also a voltmeter tester!! Not sure where voltmeter wires r connected, was in car when I bought it, also b4 new alternator with old alternator, in dash amp Gage would constantly discharge but voltmeter would read 13-14 volts!!!
OK, lets skip the under dash meter for now,
When you measure with a meter, where you measure, and under what conditions, can make a difference.
The voltage throughout the system should always be the same until it runs through a device (light, resistor, electromagnet, etc)
BUT when
current flows through a poor/small section of wiring, some voltage is lost due to resistance.
I mentioned two possibilities before. One is that the ammeter is hooked up backwards.
Flip on the dome light or parking lights and see which way the ammeter points. If shows "charge" we know some wiring is backwards.
The other thing to do is visually follow each of the power supply feeds. Make a drawing to keep track of what you see.
There are two sources of power in our cars; the alternator, and the battery.
There is a supply wire from each that goes to a welded splice under the dash. The splice is wrapped in tape. Leave it alone.
Power comes from the one that is at the highest voltage.
Uusually, when the engine is running, that is the alternator.
On a '66, once the battery is charged, about 4 amps should be provided by the alternator to keep everything running.
Flow looks like this.
And after starting up, it should flow like this. (The ammeter's scale is 40 to 0 to 40 amps.)
For the current to be flowing to the battery, the voltage supplied by the alternator must be above battery voltage!
So when your voltmeter shows 10.5 volts, if that's at the alternator output stud or the battery terminal, or anywhere in between, the ammeter shouldn't be showing charging. That makes no sense.
Typically at idle, the alternator will struggle to provide power to the heater fan, all of the lights, and also charge the battery.
So the ammeter should show less charging or no charging. If alternator can't provide enough power, then the battery takes over.
If you want to test again, charge the battery on a charger. Check the connections at the battery and alternator.
The while the engine is running and some lights or heater fan is on, check the voltage across the battery, and check the voltage at the alternator output stud (marked Batt on the alternator).
If the alternator can produce enough power, and system voltage stays above 13 V or so, current flows like this.
And I think you can picture what it looks like if it can't produce enough power.
