When I went to go to work this morning, I noticed that the battery gage read less than the normal 12.5-13 volts it normally does (around 10.5-11?). After I got home, I checked all the connections and everything was fine. So I returned the battery and they tested it-they said it was a good battery. They also charged it up also. I then hooked it back up, and let it run for a while. I noticed that the battery gage was still giving the same reading as before. The alternator is fine-had it tested a couple of months ago. So I figured the battery really must be bad. After exchanging it, I got the same result with the gage. My oil gage doesn't work properly, and my RPM gage doesn't work right as well-it is considerably off. I can only assume that it is my battery gage, right. Is there something I am not thinking of that would cause a brand new battery (or good battery) to give a low voltage reading as soon as you connect it to the circuit? I figured it should of at least gave a good reading right when I started the car. Sorry so long, and thanks for the help.

Ryan

 

If you are having problems with all your gauges I would expect a ground problem, but let's get to your immediate problem in the charging system to make sure it is not mal-functioning. Get yourself a hand held volt-meter, or have a shop perform the service for you, and check the output of the alternator, and the charge level of the battery. If you can say for sure with an accurate measuring tool, that your alternator is puting out a certain voltage, and that your battery is holding a consistent level, then you can eliminate the possibility of charging system problems, and focus on the probable poorly grounded main wiring harness. If the charging system checks out, I would take a look at the main ground wires located on the backs of the cylinder heads facing the firewall, and remove/ clean them, especially if you haven't done so in a long time/ever.

 

When I first hooked up the brand new battery, I should get a fully charged voltage output, right (even with a bad alternator). Also, does each gage have its own ground connected at the firewall? If I need to get new gages, is EBAY my best choice, or do you guys know of another?

 

Like Blownyellow said , make sure the alternater is charging first. Put one lead on the positive wire coming off the alternater ( usually the thickest wire coming from the alternater)and put the other lead to a ground. You should be getting around 14.2 to 14.6 volts. If your not getting a charge that could be why all of your guages are acting up. How does the car run because if its not charging and you have an electric fuel pump thats not a good combination.
Good Luck Dan

 

I took a reading with my multimeter and got about 12.5 volts at the alternator. I guess this is a little low-I am going to get it tested again.

My question is this:

Even if there is a problem with my alternator, shouldn't a brand new battery, as soon as I install it and crank the car up, give a full reading until it discharges to the level of which the alternator is able to generate? I also installed the previous battery after they re-charged it and it also showed the same reading (on my gauge) as the new one does. As I mentioned before, my battery gauge never gave me a full reading for my battery (~14V). It seems to always be around 11-12V.

 

The guage is for the voltage that the alternator is putting out, its not for the batteries voltage. When the car is just started that guage should show in the 14 range and after the battery gets charged it will drop a little . It seems to me that you might have a bad voltage regulater, which after 1969 is built into the alternator, since you got a 12.5v reading which is low.
Good luck , Dan

 

Thanks for the help guys. It was indeed a bad alternator. It now puts out around 14.9V at the alternator, and the gauge reads normal as it did.