1972 Battery gauge question

[Gary S.]

So here is one that I don't understand. My 72 has sat all summer long (don't ask - job situations) and I finally decide to make time to drive it. I put the battery on charge for five hours and then my wife and I will take it to a nice little drive in joint frequented by classics, rods, and customs. Click, click, click. So I jump start it and drive it for a few minutes, put it back on the charger for an hour and more clicking when I go to start the car.

No big deal, dead battery. Get a new one. And now the battery gauge starts working. My battery gauge stopped working last fall when I stored the car and I assumed that I had corroded contacts or some other minor issue.

So here is my question - can anyone explain why a car that will start and run on an old, but working battery, like it did last fall won't have a working battery gauge? No positive or negative swing with the ignition on, engine off and operating on the battery. And, in the same vein, why will the battery gauge start working the instant I put in the new battery? Is there a certain voltage or amperage threshold that must be met before it indicates +/-? K.I.S.S please.

thank you,
Gary

[Terry M.]

Re: 1972 Battery gauge question

When you installed the new battery did you clean the connections?

At minimum you tightened the connections and may now have a better connection than you had last fall. Few people realize how important a good connection is to a good automotive electrical system -- oh, and to your home electrical system as well.

[Gary S.]

Re: 1972 Battery gauge question

Hi Terry,
Nope. Did nothing except unscrew the terminals from the old battery and screw them on to the new battery. I know, from reading here, what bad connections will do to our fiberglass cars. In fact, after I bought my first corvette in the early 90's, I started yearly cleaning of the terminals on our family cars and covering them with the red battery terminal protective spray. It is certainly possible that either the connection to battery cutoff switch or the connection to the battery itself may have been bad, all terminals and connections were clean and free of corrosion.

While I am what I consider to be a competant shade tree mechanic, I have not seen this issue before. The good news? I don't have to hunt down and fix my battery gauge issue.