Same type of problems had battery testes at autozone 2000 ls v8
Cricket (2k ls 8) has been running fine, still going through all the normal stuff as I got the car used from an auction in July 11.
Recently (about a month ago), I went to the cigar store to get some rope, when I got out, I got in the car (didn't lock it) and it just got starter grind.
Apparently there was power otherwise it wouldn't have cranked.
So I got out, locked it and unlocked it (with the key) got in and it started right up.
The car ran fine for a couple of months then it happened again. Went through the same procedure and went on about my business.
One day my wife was driving it and it suddenly stalled (she was getting gas). She was able to restart the car and drive. She drove a couple of miles and stopped at a light, and the car stalled again. She was able to start it and continue about her business. (I thought maybe bad gas, we use 93 octane)
This was about 2 weeks ago.
I read about failing battery issues on this site so I decided to check it with a volt meter. I did it car off and car running.
With the car off, the battery registered just over 12V, maybe 12.5V.
With the car running, the battery registered (meter on the terminals) 14V.
Car ran fine for about 3 weeks when she called while out checking mail at our po box, and said the car would not start. So I walked her through the lock/unlock process and the car started. she got home.
Today we were out getting some errands done, when all of a sudden the car died. I pulled over and it restarted first try. We continued with our errands.
We were close to an autozone so I went had had the battery checked.
(I should note, I have no idea how old this battery is, remember got it at auction in July)
When the fellow at autozone checked it with his device, he said the voltage was 12.5V but was only half charged.
My guess is this battery is shot (it's a motocraft battery so who knows if it is original, but it's clean).
Push comes to shove, I'm going to take it out of the car and drop it on the pavement (from about 6 to 10 inches) to see if there is any crud that can be broken apart until I can replace it.
There have been some other anomalies such as the average mileage indicator going wacky (showing 6mpg then going to 18+ after driving a bit).
My experience with car batteries (and seeing this may be the source of the problem at this point) is crud builds up around the plates (at the bottom) and slowly starts to short the affected plates. Since this is not uniform, it doesn't just kill the battery. The other side effect is you can never charge the thing fully because it is always discharging internally (or shorting if you prefer).
Since the alternator is pumping out about 14V, I don't think it is the charging system (considering the test at autozone indicated the battery was only half charged), so I'm guessing the cell is bad or rapidly going bad.
My 2 cents