My battery is putting out 12.3V with the car off. I used a cheap battery tester and it indicates my battery is 75% charged.
Q: Does this mean that the battery is on it's way out? Is it possible that the battery is good and that the alternator is not charging it properly? The only symptom is slightly longer cranking time to startup than I am accustomed to. It used to fire right up and now requires 2-3 seconds on occasion.
The 12.3 is fine. I wouldn't put much stock in the cheap specific gravity tester. You say it takes longer cranking. Does it crank slower? How old it the battery? If it is cranking slower and the batt is >3 yrs old, I'd change it.
Get your battery tested with a tester that puts a load on it. Most of the chain type (and independent) auto parts places will test it for free, hoping you'll spring for a battery if it's needed. A no load test means little and a cheap battery tester is likely not calibrated all that accurately anyway.
As a battery ages its internal resistance increases and the terminal voltage under heavy load, like the starter, will go way, way down and when it gets too low, the starter doesn't turn over very fast and the engine is apt to have a harder time starting. Once the internal resistance of the battery increases too much it's a lost cause and you're better off putting your $$$ into a new battery and not get yourself stuck unable to start when it's very inconvenient to get a jump start to get you home.
I replaced my orig> My battery is putting out 12.3V with the car off. I used a cheap
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rtt
Just to follow up, I went to Autozone to get the alternator and battery tested. AFter connecting the machine and having me start the car and then rev to 2000rpm for a while, he concluded that "he thinks" the battery is bad and that the alternator is fine. He didn't seem very certain though (just me trying to read his expression). He did say that on startup, the voltage dropped to 8V at one point. I did end up buying a new battery since the one I had was at least 3 years old.
Thanks for the comments. My car still takes longer to crank than is normal. I think perhaps the starter I replaced 2 years ago maybe going now.
Carleton
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