Voltage Reading
Asked by Stephanie Oct 30, 2016 at 09:14 PM about the 1990 Ford Thunderbird RWD
Question type: Maintenance & Repair
What should the voltage of the battery read when
you use a multimeter while the car is running when
i did it read 15.05 but my battery keeps going dead
but will run as long as it is jumped and last the day
but not over night the alternator is good
6 Answers
CarsonAutoSales answered 7 years ago
If you read the voltage while the engine is running then the 15V is good, it is reading the output voltage from the alternator. Check the battery volts with the engine off. It should be above 12. Sounds like your battery is not holding a charge and should be replaced.
Thats what im leaning towards but i was told if i check the battery with no power and the amperage still drops i have a power draw somewhere then i was told to disconnect the neg cable and if it keeps dropping the battert is bad is that true
I can just disconect the negative or do i need to totally disconnect the battery
I just ran every multimeter test everything came back good even with turning everything on high nothing is drawing any extra power so now im cleaning connections
So i pulled my battery out of my car and every so often i check it and the volts are dropping really slowly so i assume thats saying this battery is junk so im getting a new one and hopefully thats the end of it
Guru94XCB7 answered 3 years ago
1978 Ford Thunderbird I have replaced the battery and alternator plus the voltage regulator Output The same 12ish Checked Wires and connection cleaned Cannot find the problem I am considering doing a conversion Ford alternator adjustable Voltage regulator one wire conversion kit HD version what do you think
