Voltage issue

Need to know exactly what they checked. The voltages you listed all say the charging voltage is too low. Minimum should be 13.75 to 14.75 volts. Doing that test with a digital voltmeter only means it is okay to perform the rest of the tests, but that requires a professional load tester. Specifically, we want to see the "full-load output current test". A 150-amp generator is the standard one regardless of engine size and optional equipment. The full-load output test will result in a reading of 0 amps, close to 50 amps, or close to 150 amps.

Obviously 0 amps is not good, but that would have shown up regardless what kind of test was performed. Professional testers will also measure "ripple voltage". If one of the six internal diodes has failed, the most any AC generator will develop is exactly one-third of its maximum rating. Ripple voltage will also be shown as "high". With a failed diode, you will still get some charging current, but not enough under all conditions. The voltage depends on how the voltage regulator is designed. Some will run the generator too hard and system voltage will be a little too high. Some interpret the high spots in the ripple voltage as over-charging, so they reduce output. This is where you'll see charging voltage is higher than battery voltage, which it should be, but not high enough.

Good evening,

Just to add, this could be the belt slipping. Your voltage is low but rises at times. I attached the diagram of the belt and the tensioner for the system. If it is loose, the charge rate will be low.

https://www.2carpros.com/articles/serpentine-belt-tensioner-replacement

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I attached a diagram as well for you of the charging system. Your voltage should be 14 to 14.5 volts running.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter


Roy