I'm not a fan of removing parts for testing. Generators need to be tested for full-load output current and "ripple" voltage. That will identify one bad diode of the six. With one bad diode the generator will only develop a maximum of exactly one third of its design rating and that's not enough to meet the demands of the electrical system under all conditions. The battery will have to make up the difference until it runs down. The test benches at auto parts stores aren't strong enough to run a generator at full load. They can only measure the output voltage, (electrical pressure). It has to be on the car to measure maximum current, (electrical flow). In most cases when the maximum current is low due to a bad diode the output voltage will still be near perfect, so you can get a false "good" result on a test bench.
All the symptoms you mentioned point to the generator being unable to deliver the required current. Have it tested on the car for full-load output current and ripple voltage before we go looking for some other cause that may not exist.
Tuesday, June 4th, 2013 AT 12:31 AM