Thanks for the clarification Gary T, I definitely had that one mixed up.
This is shaping to be a really informational thread. It’s cold right now but not tremendously so, maybe -3 Celcius.
battery terminals WILL corrode no matter how tight your connections seem or how long it has worked with no problems.
Use a wire brush and clean the terminals and the posts and see if it makes a difference. If it doesnt then likely you will need a new battery.
If the car started (i wasnt entirely clear on that from your post) and THEN the lights began to dim and the power failed, then your problem is not with the battery but rather with the alternator.
ONLY do this with the battery completely disconnected from the car cables, test it like this with ONLY the tester leads attached correctly to the posts.
Also, a fully charged battery will Never read only 12 volts. A fully charged battery SHOULD read as 14 to 15.5 volts immediately after a charge and should settle to 13.5 to 14 volts.
A read of 10 volts is basically “dead” and needs replacement.
Resistance? AH, so there are Three (3) components to electricity (unless someone wants to interject watts here, and that would just be ridiculous)
And 6 cells of 2.2 volts each would equal how many volts total? Not 12.2, but 13.2 (even though each cell is actually 2.4 volts giving 14.4volts total read for 6 cells - theoretically. Realistically it is more, like 15.5 volts for 6 cells )
I really hope the OP has resolved the battery problems by now, it being 11 years since asking!
tl;dr, but:
The key might be the age.
Battery terminals are/were a lead alloy or something similar.
As they age under tension (as in being clamped tightly to a post) they stretch. The inside diameter expands so that a tightly clamped terminal is still loose,
Wiggle the battery terminals.
A quick fix is to drive a small brad between the post and the terminal. Crude, but it works.
Moderator Action
The OP of this thread hasn’t been active on this board since 2004, and other posters to this thread are also no longer around.
DanDrum, please do not bump old threads.
If anyone wishes to discuss car batteries in a more recent and relevant context, feel free to start a new thread.
Thread closed.