Generator dash light

On my 1976 Cadillac superior combo - occasionally I will see the GENERATOR dash light dimly lit - mostly at idle. Battery is one year old and after running the the car for a time, the next morning the battery reads 12.4 or more volts. There are no beacons or sirens, just headlights and I was running the heater tonight. Any thoughts? Thank you GaryK
 
most likely a regulator problem. as soon as the rpm comes up it goes put. but check the idle speed. if it's a little low you can get that in gear at a stop sign
 
Battery age isn't always a good way to check a battery. You need to check the voltage after manually charging it, and then let it sit for a day, and check it again. If it doesn't loose voltage, it is safe to say that all the cells are working as they should. The second thing that needs to be checked is the alternator output voltage. This is a little more difficult, unless you have the proper equipment. There is a slight possibility that there is a damaged diode in the alternator, or it could be something simple as a loose belt, causing the belt to slip when the vehicle calls for full output of the alternator. Depending on the alternator that is installed on your car, the fix can be inexpensive, or very expensive. If you have the 130 amp alternator, it will be expensive, and parts are difficult to find. What sometimes is even more difficult, is finding someone that knows how to work on that alternator. A good alternator repairman will have no trouble fixing it, if you can find the parts. Problem is that it has to be disassembled and each diode needs to be checked to see if it is good or bad. When mine went out on my 1969, it took me almost 3 weeks to get the parts needed from a few different suppliers. No one supplier had all the diodes that it required. I did luck out with a shop in California that Kevin O'Connell recommended, however, I recently learned that the shop had closed. Kevin has no idea what became of the inventory.
 
My experience tells me that you should probably have the alternator rebuilt. Having said that, I defer to the experts here, of which I am not one.
 
Along with all that aforementioned, go to a reputable battery dealer and have them load test the battery. That will tell you if there is a bad cell or not. Age sometimes does not matter.
 
if the only time you get the flicker or dime light going in and out is at a idle in gear it is ault out put. most likely due to low speed of the alternator. if you move out and it stays out you may just need to increase the idle speed. when is the last time the car was tuned up? do the simple stuff first check the belt make sure the engine is operating at specks. if the problem was coming and going at all speeds then it's most likely the ault. a bad battery will eat up the ault. but it will be showing other problems also. a poor connection also but they usually come with other problems also. a flicker or dimming at idle is normally just low engine speed.
 
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