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  #1  
Old 01-17-2022, 11:34 AM
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Battery fully charged tops out at 12.4v

I have a AGM from 2017 that even after leaving it charging for 3+ days, as soon as its disconnected and I turn the lights on for 3 minutes to remove that "phantom" charge and the battery drops down to about 12.38v-12.4v.

Is that a typical sign the battery is beginning to degrade, or nothing to worry about?

Reason I ask is that after a few weeks I'm dropping down to 12.2v and then starting begins to be a little sluggish.

thoughts? thanks

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Old 01-17-2022, 11:49 AM
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Yep, battery getting tired. 5 years is a good life on batteries anymore.
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Old 01-17-2022, 02:52 PM
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i got ripped buying a used AGM once so i sprung for a hand held tester and it has really come up huge for me. i went to see a 'new' old stock' red top optima that was showing 12.4 v but the CA and CCA were both at about 20% of what they should be (1000 CA was 225 and 850 CCA was 171)

also invested in a C-tek charger that has a reconditioning function and that has rejuventated a few that seemed to be going away on me
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Old 01-17-2022, 03:22 PM
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Originally Posted by Hogweed View Post
i got ripped buying a used AGM once so i sprung for a hand held tester and it has really come up huge for me. i went to see a 'new' old stock' red top optima that was showing 12.4 v but the CA and CCA were both at about 20% of what they should be (1000 CA was 225 and 850 CCA was 171)

also invested in a C-tek charger that has a reconditioning function and that has rejuventated a few that seemed to be going away on me
I could try and use the reconditioning on my Nocco 5amp charger and see. I know the CCA are still pretty good at 750.
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Old 01-21-2022, 12:34 PM
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Quote:
Originally Posted by ps2cho View Post
I have a AGM from 2017 that even after leaving it charging for 3+ days, as soon as its disconnected and I turn the lights on for 3 minutes to remove that "phantom" charge and the battery drops down to about 12.38v-12.4v.

Is that a typical sign the battery is beginning to degrade, or nothing to worry about?

Reason I ask is that after a few weeks I'm dropping down to 12.2v and then starting begins to be a little sluggish.

thoughts? thanks
does the battery have above 12.5V after being parked overnight? If you are getting low volts after a few weeks, then probably your battery is toast.
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  #6  
Old 01-21-2022, 02:36 PM
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I would test the cold cranking amps on the battery to see what percentage it holds compared to what it is rated for.

Also, after putting that load on the battery you might have to wait a while for the voltage reading to rise and to be accurate.
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  #7  
Old 01-29-2022, 08:39 PM
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Originally Posted by jdulle View Post
I would test the cold cranking amps on the battery to see what percentage it holds compared to what it is rated for.
Good advice! I always do that if a battery is suspect. But you do have to get the battery fully charged first (or at least full as it will take in say 12 hours with a decent charger.

I used to only have those basic Sears and other chargers. I then bought a marine smart charger and haven't looked back. It is marine version of this one that they now sell here in Canada I am sure there are equivalent units available in USA.

Basically what I am trying to say - Get a decent charger! Get the battery as fully charged as you can, then do a load test with a cheap unit like this.
https://www.schumacherelectric.com/products/battery-load-tester/
Or maybe one of the more sophisticated electronic units! They were out of my price range, but looked neat
https://canadianbestseller.com/pd/ancel-bst500-12v-24v-100-2000-cca-automotive-battery-load-tester-car-cranking-and-charging-system-analyzer-scan-tool-with-printer-for-heavy-duty-trucks-cars-motorcycles-and-more/?v=3e8d115eb4b3#gsc.tab=0
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  #8  
Old 02-15-2022, 11:55 AM
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I had a problem charging an AGM battery with a C-Tek charger.

With the battery connected it charged only to 12.4 Volt.
With the battery disconnected it charged to 12.85 Volt
The battery is a 5 year old Varta AGM.

A warning, the reconditioning program of the C-Tek can destroy the voltage regulator of the alternator. Always disconnect the battery when using this program!

Rob

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