Got an odd question, and after a couple quick searching ..didnt see anything that helped too much .. lot of redtop vs X type battery discussions.
I've always been told you can follow some general guidelines on battery testing. Not exact but its always been close.
At least in a pinch it has always worked out for taking a battery for replacement...
Fully charge a battery, let it sit overnight .. or pull turn on the headlights for a couple minutes to bleed off the surface charge.
Then Check voltage with a meter
12.75v - good battery
12.25v - iffy....retest or replace
11.75 or under - Your asking for trouble..
Anything under about 12.25 indicates either a bad charge or bad battery.
Usually i run it twice on something that im not 100% sure on, those that fail my test get a visit to the local parts shop for a test/replacement.
SO far its not failed me or left me stranded.
Now to what leads me to the question.
Only had this car around a year now. Out of the year I've never had any issues wit the the car sitting a week or two.
This time I've not driven the car in about 3 weeks ....went out to drive ..and nothing .. not even door locks, thought my fob was dead to start with .
Nope ... Sure enough battery was dead.
Couldn't find anything that might have been left drawing power in the car. It looks like the date on the optima red is from late 2009, (on when i bought it ... guessing it could have been installed even during 2010.
Ran through my testing..
I did check to make sure my charger would be ok with the battery type .. Found nothing indicating problems .. and i was able to charge it from its current state up.
On the optima red tops i'm the readings are the same however
Fully charged one over night... 6amp for 1 hour .. then 2 amps for 6-8 hours. Then it trickled charged for about another 12 hours.
Was up to about 12.8 volts around this point.
I let it sit overnight .. pulled voltage ... 12.15 volts.
Typically i would test about from trickle or 2 amp charge again, but if i drop the trickle charger on it .. Its showing fully charged at this point. Car cranks just fine over night. everything seems fine ..
Voltage just seems low, not low enough to be a dead cell ... but lower than what I'm used too seeing.
Of course this has me wondering if the sitting voltage might be a little less on the AGM batteries than the older flooded batteries I'm used to working with. And of course its got me a bit hesitant to drive the car at any length til i resolve it.
If nothing else i may pull it out and have it tested in the parts store ..
Anyone have some suggestions?
I've always been told you can follow some general guidelines on battery testing. Not exact but its always been close.
At least in a pinch it has always worked out for taking a battery for replacement...
Fully charge a battery, let it sit overnight .. or pull turn on the headlights for a couple minutes to bleed off the surface charge.
Then Check voltage with a meter
12.75v - good battery
12.25v - iffy....retest or replace
11.75 or under - Your asking for trouble..
Anything under about 12.25 indicates either a bad charge or bad battery.
Usually i run it twice on something that im not 100% sure on, those that fail my test get a visit to the local parts shop for a test/replacement.
SO far its not failed me or left me stranded.
Now to what leads me to the question.
Only had this car around a year now. Out of the year I've never had any issues wit the the car sitting a week or two.
This time I've not driven the car in about 3 weeks ....went out to drive ..and nothing .. not even door locks, thought my fob was dead to start with .
Nope ... Sure enough battery was dead.
Couldn't find anything that might have been left drawing power in the car. It looks like the date on the optima red is from late 2009, (on when i bought it ... guessing it could have been installed even during 2010.
Ran through my testing..
I did check to make sure my charger would be ok with the battery type .. Found nothing indicating problems .. and i was able to charge it from its current state up.
On the optima red tops i'm the readings are the same however
Fully charged one over night... 6amp for 1 hour .. then 2 amps for 6-8 hours. Then it trickled charged for about another 12 hours.
Was up to about 12.8 volts around this point.
I let it sit overnight .. pulled voltage ... 12.15 volts.
Typically i would test about from trickle or 2 amp charge again, but if i drop the trickle charger on it .. Its showing fully charged at this point. Car cranks just fine over night. everything seems fine ..
Voltage just seems low, not low enough to be a dead cell ... but lower than what I'm used too seeing.
Of course this has me wondering if the sitting voltage might be a little less on the AGM batteries than the older flooded batteries I'm used to working with. And of course its got me a bit hesitant to drive the car at any length til i resolve it.
If nothing else i may pull it out and have it tested in the parts store ..
Anyone have some suggestions?
You're correct in the initial rough battery testing proceedures, just make sure the battery's not hooked to anything. From the way you're doing it, should read about 12.8 volts. Only means all the cells are functioning to some degree, but maybe sulphated up. If so, the battery wont supply much current, and quickly self discharge. You'll really need a load or conductance test for a better idea. I have a Midtronics 200 conductance tester that calculate's availible CCA plate area. You'd be suprised how many batteries show decent terminal voltage, with very low CCA. Some chargers like Ctek's have de-sulph circuitry, but don't think it's for really bad stuff.
