Similar problem as Albert with a twist

Probably a bad diode in the alternator.

Suburb Hi,

Try changing the voltage regulator here is why I state that you car is over charging the battery at 14.8 volts dc... Max is 14.5 VDC. you will burn up the battery at 14.8 all the time.

Here is what I know (some of what I know smile.)
normal charging rate of any car to properly keep the battery charged is 13.7 to 14.5 volts... Except as my late father would say below.

Hint... Measure the battery with a volt meter on DC ( which you did)
Then measure it on AC if you have a bad diode then you will produce an ac voltage, if it is shorted (what I call DC with an AC constant)

I will tell you this... My car which I have had for years, at idle, is under 13.7 volts closer to 12.7 but as soon as you give it gas it jumps to 13.9 to 14.2 Vdc. My dad came over on the boat from Italy and made his way thru life as an electronics tech (tv radio) he told me as long as you are charging 1 volt over the non charging battery voltage you are ok.

PS I installed a new alt and voltage regulator, and it did not change. I have checked every connection and termination. No Problems.
PS PS I am an Electrical Engineer.

As Forest says it could be a bad diode in the alt but the voltage relay is cheaper and easier to swap first.

Joe

A good alternator is $35 to $250 the better is best, the best fix? get rid of that old junk, just wire in a Chevy 1-wire alternator.

Hey Chris, how mutch would that be, easy to install, build in regulator? Thanks Urbain.

The GM 12si alternator works well. They are available at most parts stores and should be available in your location. The one wire version needs spun up a bit to start charging and the 3 wire (which is actually a 2 wire since you loop one back onto the battery terminal) lets you keep your indicator light and starts charging as soon as the cars starts. I prefer to keep the light since it gives you another visual notification if you have a belt or alternator failure.

If you change it to the GM, you will need to drill out the mount to 7/16 since the mounting hole is for the 10mm bolt and the ford is 7/16. You will also need a 1 inch thick spacer for the back of the alternator mount since the Ford mount is 3 inches and the GM is 2 inches. The pulley location is oriented correct when you keep the front the GM alternator forward on the mount.

Here is one mounted to a bulkhead reduction kit mount next to a SD508 rotary compressor.

Another view.

Kirk. Please give me a call next week. Mike Mayberry 818-424-2694

How easy, Kirk has answered that question, spacer is the biggest problem and that isn't much, I have never had or see the spin up to begin charging as a issue, after 1000rpm at start the exciter kicks in, and to clarify it charges continually at any rpm and you just run 1 wire to your battery (and the little wire to the trouble light), this alternator has huge after market support (available anywhere) The oem's are cheap, but they didn't last,the problem is their is no or very little air circulation in the bubble, it gets hot in their! I stepped up to a powerhouse $250.00 that was 8 years ago, 0 problems.

Whats wrong with the Ford gen 3 alt?
Got a after market example , has internal fan ,internal regulator, no mounting adapters , bolts right in.
Pa Performance # 1614E , small case , 95 amp off idle , up to 120 amp max.
Pa Performance has a over priced box that looks like a Ford external regulator that perserves the idiot light.
A word of caution I used a #4 wire from the output terminal to the starter solenoid and a 120 amp manual reset circuit breaker on the fire wall. Stock wires look under sized for the stock alt. The amp meter was replaced with a expanded scale volt meter. (fire hazard)
The stator out put will drive a relay so the electric choke only has power if the engine is running. I am sure no one has ever borrowed ignition power to power the choke.
Something seems a little off to use a AC Delco alt on a Ford product , even if every parts store has one in stock. I am sure there is a Ford alt in the salvage yard , have not researched it.