Car is done but now it runs the battery down

[Pa's Sat]

I have finished the rebuild on my 66 Sat. and added AC to it for comfort. Still have the original alternator in it (rebuilt) and at idle it will discharge the battery. Just wondering if I can get a bigger alternator (like 100 amp output) that will help? If I do that, do I need a different voltage regulator? It's running good otherwise and enjoy driving it. Any suggestions would be great as I am not up on the electrical part. Thanks

 

[monaco66coupe]

so does the car charge with A/C off? if you have a stock non A/C alternator, then at Idle with air on you could see that. However, it is possible you just have a faulty regulator. also be sure the engine is grounded to the body, with that strap on passenger side rear of engine.

 

[pnora]

A/C will not be causing your problem. When you say discharge at idle does the battery go dead? Does it charge above idle?

 

[qkcuda]

I changed my car to a modern solid state voltage regulator and it solved that problem. It looks just like the original, but has solid state internals.

 

[Pa's Sat]

The motor is grounded to the body. It looks like it is a slight discharge at idle with no fan or air on. It does charge with some higher rpm.

 

[monaco66coupe]

which engine do you have? the non air could have a 30 amp alt, but the A/C versions had a 46 amp alternator. 30 amp is enough to operate properly as long as there is not a heavy load on it, so I still feel the Regulator is not doing it's job, if at Idle the needle is straight up or leaning left. how far does the gauge go when you Increase RPM? a little, or a lot?
also, pull on the lights, and see if the gauge heads left big time, or does the gauge compensate, or at least try to?

 

[monaco66coupe]

If you decide to buy another regulator, take the alternator with you, as most places will test it for free. Even though it may have been rebuilt, something could have gone bad.
whatever you do ,don't go real big on the amps, the car is not wired for it.that year all current flows thru the ammeter, they can melt/burn up.Many a dash fire occured with the old cars because of that.

 

[Don Frelier]

Welcome from NY.
I wouldn't worry too much as about it.
Your battery isn't going to go dead in five minutes with a slight discharge.
There's likely nothing wrong with what you have.
If I have the headlights on and hit the brake on my charger it discharges fairly good.
It's done it for 30 years. As long as when you drive five or ten minutes steady it should show just a slight bit of charge above center.

 

[Pa's Sat]

It has a 318 now bored out .30 and came with only power steering. I added AC now. I will get the alternator tested and find out what its output is and maybe a new regulator.
When idling the gage will go slightly left if anything is on but does go right with some increase of rpm.
Don't want to have a dash fire now.
Thanks for the help!

 

[monaco66coupe]

It has a 318 now bored out .30 and came with only power steering. I added AC now. I will get the alternator tested and find out what its output is and maybe a new regulator.
When idling the gage will go slightly left if anything is on but does go right with some increase of rpm.
Don't want to have a dash fire now.
Thanks for the help!

yep, probably a tired unresponsive regulator, it happens allthe time. Don't lose your original alternator, all these stores are selling high output units, and a 66 Satellite don't like that!

I know, I have had belvederes since 1995. this one I restored in 2001. 440 HP original

 

[moparedtn]

Pretty common actually and like others have said already, not necessarily a sign of something
being "wrong".
What RPM is your idle speed? Would bumping it 50-100RPM bring the charge up acceptably?
Alternators need a certain minimum RPM to do their thing.
I totally agree with replacing the voltage regulator with one of the electronic ones - and sure,
use the one that looks identical to the one you have now if you like.

 

[440+6]

I had the same problem years back, took my alternator to a local alternator rebuilding shop and just had them put a smaller pulley on it, been perfect ever since.

 

[Hey-O]

Welcome from Missouri!!

 

[HD539]

Welcome from the Pacific Northwest

 

[Budnicks]

welcome to FBBO

 

[440 Charger]

It has a 318 now bored out .30 and came with only power steering. I added AC now. I will get the alternator tested and find out what its output is and maybe a new regulator.
When idling the gage will go slightly left if anything is on but does go right with some increase of rpm.
Don't want to have a dash fire now.
Thanks for the help!

Led is the new way.

 

[polywideblock]

g'day from Australia

 

[Pa's Sat]

Had the alternator checked and was good. Replaced the voltage regulator and that took care of it. It will now show a straight up or leaning to the right at idle and stays there with the lights and fan on. Thanks for the ideas and help. This is a great place for help!