Battery Tester Diagnostics Uncovering the Causes of Voltage Swings

The fluctuation happens when parked and driving while increasing engine RPM's. ... First check all the wiring connections to the alternator ... A good battery with engine off should read 12.5vdc. Your charging system (DIC) when running should read about 14.2vdc. There is always the possibility that the battery is simply at its end of its useful life. Voltage readings of the battery and during charging ... Noticed today my volts are fluctuating while RPM's are near or above 2000 on highway trip. At stop light had battery light come on. Make sure your cable from alternator to battery is absolutely clean and makes good contact at the alternator. Always use dielectric grease on ... Seems to be a normal variance between charging/not charging once a battery is essentially full. Your fairly lengthy trip probably gave your ... I installed a AGM battery and with a volt meter I am reading 14.9-15.3 volts at the battery with it running in park. The needle on the dash ... No it will NOT immediately go to 14 volts while the grid heaters are cycling...they pull a huge amount of current, more than the alternator can ... The voltage regulator shuts down the alternator as the battery reaches its charge and the gauge gradually drops to battery voltage. When there's ... (take it off the truck, your local auto parts store should be able to test it.) If the alt tests good, voltage regulator is bad, which, ...