Battery, Good or Bad?

[Tazman]

Out here in AZ our batteries do not last to long.I went to autozone and had mine checked.Was told it was bad yet it has 98 % charge in it.Can some please explain to me how can that be?I think the guy is trying to sell a new battery. Thanks

[Irish_Alley]

It means its a fully charged volt wise. But it doesn't have the cranking amps to turn the motor over. If you try to bring in a dead battery from a truck that was sitting for a month it would say " charge and re-test" so you do need a new battery just cause its holding 12v doesn't mean it will turn over the engine

[topp]

Nor will it possibly hold that charge for long.

Several reasons for a battery to have voltage and still be bad

[slammed79]

Bad cells. If you have the money, get an Optima, they hold up better than anything I've tried to this clustered weather we have down here.

[Irish_Alley]

i do have an optima in my 94 its 6 years old now and i got it from a customer at autozone who drained it dead and who knows how long he had it before then. he said it was old and dead so he used it as a core i charged it and used it in my 86 then in my 94. i would of used it in my 79 but i have a winch so i use a deep cycle

[zieg85]

My company car a 2009 Ford Escape, had it about 15 months/70K miles at that point and my battery tested bad...  On the other side of the coin I just had to change the battery in old faithful, my 1985 C20, battery was dated 10/02...

[bake74]

     If he tested the battery right, he would have done a full load test and draw test.  As stated before, a battery can show 12 volts but still not be good enough to crank at the rated cranking amps.  As slammed said, if cells are bad you can charge the battery and it will show 12 volts, it might even hold 12 volts for awhile, you start cranking that battery and it will go dead in no time flat.

[Irish_Alley]

I remember testing some batteries that would read 12 volts but when you tested them if it drops below 10 volts during the load it would test bad even if it returned back to 12

[PromiseKeeper]

Just curious, but why were they testing it? There must be a problem somewhere? Most likely he did it in the parking lot and you could watch what he did and see the results. More info might be helpful to get a better answer.

[Tazman]

I went to three places to have it tested and got three responeses the last suggesting to change it as soon as possible which I did.Had free replacement so all I was out was my time.Thanks

[roadrage41]

Interstate megatron. Any battery issues go to them honestly, batteries is what they do.

[roger97338]

Not that this pertains to your battery, (maybe it does, maybe it doesn't), anyway....a 12 volt battery is actually 12.6 volts. Each cell produces 2.1 volts, times six cells, equals 12.6 volts. So, if you charge your battery completely, and the next day you put a volt meter on it, and it's only 10.5 volts or thereabouts, one of the cells is bad.

Or, if you have a hydrometer, check each cell with it. Five will read 1.265 specific gravity, and one will read 1.000 s.g. (Or pretty close, anyway.)

That's just to check for a cell short, aka bad cell. Occasionally, one of the connectors between the cells will break, and you'll have a "broken inter-cell connector." And batteries also get weaker with age, they freeze if they're dead and the temperature drops below freezing, or if they sit for a long time without use, the acid will crystallize on the plates. Which is sometimes reversible, sometimes not.

Many years ago, I sold batteries to commercial accounts. I learned a thing or two, and just wanted to pass it along.