QuestionI have a 62 thunderbird with 17 volts in the battery.I have turn the lights on without starting the engine to try to discharge the battery which the lights get dim and the volts on the battery our about 8 or 9 volts.When I turn the lights off the battery jumps up to 17 volts again and now the car wont start. Why is my battery getting 17 volts and why when the lights our turned off the battery goes back to 17 from 8 volts when the lightsour left on. Can I still charge the battery up without frying the battery to just start it again. Thank you so much. Larry.
AnswerIf your battery is a normal 12 volt car battery, there isn't any way for it to be showing 17 volts when the engine isn't running, so either you have a defective voltmeter, or you are making some kind of a mistake in measuring it. A 12 volt battery has 6 cells, and each cell can generate at most 2.3 volts, so the maximum you can read for voltage from the battery is 13.8 unless it is being charged when you measure the voltage. That is an absolute limit, due to the chemical reaction that generates the voltage.
If you are not familiar with electrical measurements, you need to get the car to an automotive electrical shop and have them figure out what is going on.
If you have a normal type battery charger, yes, you can charge up the battery so the car can be started. To avoid damaging anything in the car, disconnect one of the battery cables while you are charging the battery.
If you take the car to an Auto-Zone store, they will diagnose it for free, if you buy whatever parts you need from them. Other auto parts stores do this also, so if you don't have an Auto-Zone in your area, call around to the other parts stores in your area to see if they offer the same free service.
Dick
