Q: Folks, what's the charging voltage (as measured at the battery terminals) supposed to be for a 1991 V8Q ?? My battery fault indicator keeps going on, especially when the lights are on. I'm measuring 13.65 V on the terminals with the lights off, 13.45 V with the lights on. Should be ok? Battery is 2 years old, brush / diode pack was replaced a year ago. I jump started a poor unfortunate soul driving a Volvo today, his battery was very dead, way worse than I thought, and I initially tried to jump it without my car running and it dragged the battery right down, I had to start my car and let that POS volvo charge for a bit before it would start. Do you folks think I damaged something, like the battery maybe?
A: Have your battery fully charged and then load tested. If it passes the load test, you have another problem. You might possibly have an alternator problem. You could have possibly blown a diode inside the alternator. You should be measuring closer to 14 volts with the lights off. 13.65 is okay, but it seems like it should be higher. WIth the battery light coming on it and the voltage being slightly lower, it sounds like a diode is leaking. Try finding an independent Starter and ALternator shop, they should be able to help you. If you take the alternator off of the car, it can be tested on a machine tester for draws, and bad diodes. Some places might have the equipment to determine a bad alternator without removing it. First have the battery tested to make sure it is okay. Hope this helps and I wish you the best of luck.