84 Cutlass Supreme Brougham battery/charge question

[Richard S]

My daughter has a 84 cutlass supreme that doesn't like to start all the time. I thought it was the battery, took it out and took it to parts house to be tested they say battery is good. I still have to jump it occasionally. I took the negative battery terminal loose tonight and put a test light between the negative cable and neg. post on the battery (switch is off) no light on test light.
I then used a voltmeter red to pos. and black to neg in the 20 Volt range. engine not running I get 12.85 V. Start the engine then it goes to about 14.75. Battery is about 2 years old. I still have doubts about the battery but I'm not sure. Any ideas would be greatly appreciated thanks in advance.

[MagicRat]

Your voltage readings are very good. Virtually all cars in good working order will show similar readings.

Your test light process only demonstrates your car has no unnecessary electrical drain... again that is a good result.

IMO I think your terminals are dirty/.corroded. Try removing both terminals and clean up the cable ends and the battery terminals with a wire brush until they are nice and shiny, then reinstall them and see if the situation improves.

Also, clean up the ground cable where it bolts to the engine.

[Richard S]

I forgot to say I have already done that. My oldest daughter has a Buick that had terminal/bat cable problems so I used the same process. Cut away the red /black plastic and took the cable to the grinder with wire brush and cleaned both ends. That cured the problem on the Buick, but hasn't on the Olds. A battery shop also told me to put grease over the terminals after reattaching to keep down corrosion. Thanks I will keep looking and post back what I find.

I talked to a mechanic I know today and he told me to change the battery. I went to auto zone and had the battery tested again today. He told me, which I was not aware of, the way they test is only for load and to see if cells are bad and not whether the battery will hold charge. He told me also by the test that I run it eliminated the electrical system in the car, and only thing left was battery. He told me he has run into this quite a bit lately. I guess time will tell.

[Richard S]

I think the new battery did the trick, I would have had to jump it by now. Lesson learned if it continues to hold.

[Richard S]

I guess I jumped to conclusions to quick. New battery was dead this morning. I used a different test light that reads lower voltage something like 3 volts and light comes on. I also used amp meter in between neg post and neg cable end. It is drawing 13.6 amps. I have a book that says it should not draw more than .5 volts. My son and I pulled every fuse one at a time and light never went out on tester. I am thinking maybe I need to pull two fuses at a time in case one circuit is shorted to another. Is is possible to have a bad switch, and is there a way to test for that? I read something in the book about a bad fusible link but the way I am reading it, if correct the vehicle would not start. It does start.

[MagicRat]

You most likely have a bad starter motor or starter solenoid (which is attached to the starter). Try disconnecting the thick battery cable that goes to the starter motor and see if the light goes out.

[Richard S]

I made a typo don't know how much of a difference it makes, but I'm sure it is quit a bit. It was set to millamp. 13.6 mill amp draw. I am still going to check the wire to starter. My regular test light won't come on when it is between neg cable and post but it will light if I put it across the battery. I forgot to look at the idiot light to see if it comes on when the switch is on but I took the alternator out last night and am going to have it checked. I could have a burn out light on dash, that should have been the first thing I checked but. Thanks I will post back what I find.

[Richard S]

I think I may have fixed it today. I changed the battery cables. Negative and Positive. Did not have to jump. It started on its own. As usual with my luck though found more problems. I guess better to find them in the driveway than the side of the road. Have a great day. Thanks.