12.3v in the morning indicates there is an undercharged battery, a parasitic draw, or a sulfated and undercharged battery.
Cold temps can of course also draw down the fully charged resting voltage.
The right charger can make a difference, but the Odyssey chargers are quite expensive for a Schumacher charger with a different algorithm.
Strangely, these top out at 25 amps, when they say their group 31 requires 40 amps minimum. Yet this 25 amp charger is 'approved' for their group 31. Very few 40 amp 'smart' chargers on the market.
Really on these TPPL AGM batteries, the prescribed recharge regimen is most important only when deeply cycled or often cycled to below 80% and incompletely recharged time and again. The 80% to 100% takes no less that 3.5 hours when held at ideal absorption voltages, so short drives with lesser voltages in the 13's simply will not do it, nor make the battery truly happy where it will perform best and last the longest.
Your Die hard platinum/Odyssey battery
is showing some signs that it is not so happy, but it is nowhere near the recyclers, not with a proper recharging.
I wonder what someone would pay to have their battery properly reconditioned by someone with the tools and knowledge to do so properly, and not someone who just claims to do so, and is also a battery retailer?
I'd hate to have to guarantee a restoration of capacity and CCA. One does not know if it will be successful until it is tried, and if successful, how long would it last. Lots of Guess work. No guarantees unless the results are glowing.
I got sick of automatic smart chargers telling me the job was done, when a hydrometer screamed "FOUL!!!, LIAR!!!!", and the battery cried.
I now use a adjustable voltage power supply capable of 40 amps, and control voltage and the duration the battery is held at the voltage I choose.
If you delivered me your group 34 Odyssey TPPL AGM battery to 'recondition'...
Here is what I would do.
Assuming a battery and Ambient temperature of 77F, I'd just turn my power supply to 14.7v and let it run until amps tapered to under 0.32a.
I'd let it rest 24 hours with no load, and check voltage, and 'If' I had your solar tester impedance device, take and record a baseline reading.
Are battery impedance testers worth it? Please read this:
http://www.pbase.com/mainecruising/impedance_testers
That guy's knowledge and experience in this area, are second to none, in my opinion.
Granted the article linked above is more concerned with deep cycle battery capacity rather than cold cranking amps of starting batteries, but of course there are strong correlations, and the Odyssey battery is regularly deeply cycled by the boating crowd, and I regularly deeply cycle a Northstar TPPL AGM battery which is very similar.
To this now 'fully' charged, but lazy battery, I'd apply a load, the load at which it earned its 68Ah 20 hour capacity rating. 68 divided by 20 is 3.4.
I'd try and find a load which was steady at 3.4 amps, but the lowering battery voltage during the discharge, will usually make this amperage also change, so it would not be a truly accurate 20 hour capacity test, but it would be useful for comparison to the test subsequent to the high amp and complete recharge as long as the same load was employed both times.
When battery voltage fell to 10.5v (100% discharged) under that 3.4 amp load, I would record the time it took since I first applied the load. If the load were exactly 3.4 amps the whole time, for 20 hours before voltage hit 10.5v, the battery would be rated at 68 Amp hours as when newish and broken in with a few cycles on It. Deep cycle flooded batteries actually increase in capacity slightly for the first 2 or 3 dozen cycles as long as they are recharged properly and completely. Not sure about CCA figures or how AGM's compare, break in wise.
From this 100% depletion to 10.5v under that 3.4 amp load, I would then apply my 40 amp power supply set to 14.7v, and let it go, monitoring temperature that first few hours. If battery got above 115F, I would terminate the charge and let battery cool, then restart the charger. I have an Amp hour and watt hour counter on my power supply output and it would be interesting to see how many AH accumulated before the battery terminal voltage rose to 14.7v for comparison to the next test, and how many accumulated before amps tapered to 0.5% of capacity.
From the time ~14.6 volts is attained at the output terminals of the Charging source( there will be some voltage drop on the 8awg cables at 40 amps), the amps will start tapering. If the battery is healthy, it will require about 4 more hours being held at 14.7v for amps to taper to 0.34 amps, at which point it can be considered 100% charged.
IF the battery is unhealthy, this tapering, constant voltage, absorption stage, might take 8 hours, 12 hours, perhaps longer. One can only guess then observe the ammeter, perhaps raise an eyebrow. Temperature is still a concern. If 120f was flirted with, I would again terminate and allow to cool then restart. If it did approach this temperature with an ambient temp of 77f, it is not a good sign of battery health.
After amps taper to 0.34a or less, Which is 0.5% of 68AH, I would terminate charging and let battery rest for 24 hours, then take a voltage reading, and let the impedence tester do another reading, and compare to the original readings.
Odyssey says that a second 100% discharge and a high amp recharge is beneficial for reconditioning, so I would restart the load test with the same 3.4 amp load, and see how long it took for battery voltage to drop to 10.5v.
I'd then initiate the 40 amp to 14.7v recharge again, and compare all recordings to first high amp recharge.
How long to 14.7v was attained?
How many Ah had accumulated before that voltage was reached?
How long between when 14.7v was attained compared to when amps tapered to below .34?
Is the capacity anywhere in near the 68Ah rating the battery had when new?
If so, let out a Homeresque Whohoo!!, and dance a Jig.
Is it only ~80% of when the battery was new? Well the failure rates of batteries under 80% of their original capacity is much much higher than those with more than 80% of their original capacity.
If it was in the 80% range, I'd ask the battery owner if they wanted me to try Lifeline's reconditioning procedure.
If affirmative, since the battery is already fully charged, I would reattach it to my power supply at 14.7v, wait the 30 seconds or so it would take for amperage to taper again to under 0.34a, then I would bump up voltage slowly, watching ammeter, keeping amps to about 3.4 or less and making sure 15.5v was not exceeded.
Lifeline says hold 15.5v for 8 hours. A healthy AGM battery would likely taper pretty quickly to 0.5 amps again, but the unhealthy might slowly taper from 3.4 amps, and might heat up considerably more. If at any point the amps required to hold 15.5 start rising instead of dropping, I would terminate the 15.5v reconditioning as thermal runaway could be starting.
I'd monitor for that 120F degrees for those 8 hours at 15.5v if amps to hold 15.5 had not risen.
After the 8 hours I would then lower voltage to 13.6v and float the battery for 12 more hours.
I'd likely not perform another 20 hour capacity test unless requested to do so, but the impedance tester results would be interesting to compare to earlier readings.
The battery Would likely not respond to any more high amp recharges or lifeline's 15.5v reconditioning procedures
Likely as good as it gets, and restored back to its maximum remaining capacity and CCA and lifespan from that point.
Obviously a pretty good amount of time/effort/observation is required, and the proper tools, but if you read this far, can see why the little green light on your smart charger is pretty much a bald faced liar one should not trust withuot a whole lot of skepticism and doubt. Try and look past the fresh purchase confidence in the product bought and its extra special marketing with a cherry on top, as without some tools and knowledge applied, one battery looks just like another when it still starts the engine.
Those wanting to use what they got to do the best they can on a questionable battery, when their charger first stops and flashes the full charge green light, unplug charger from battery and AC outlet, load battery until voltage falls to below 12.6v, and restart charger. Lather rinse repeat, and hope, but do not hold your breathe.
The smart charger might have ambient temperature compensation. If so cooling only the charger might allow it to seek higher voltages for a quasi equalization/reconditioning charge, but do monitor voltage
Many of the old school manual chargers can get to and above 15.5v, but they can do so without stopping at ~14.7v for the ~4 hours, and that is unnecessarily abusive to the battery, but is effective, especially when time is a factor.
Trojan battery, and Rolls Surrette, two kings of the flooded deep cycle battery world, prescribe an Equalization voltage of 16.2v.
The test I would perform above is for an AGM battery. With a flooded battery I would use 14.8 volts as absorption voltage, and for the secondary LifeLine AGM reconditioning/ Equalization stage, I would go to 16.2v.
While flooded batteries can accept these rather large amperages when depleted, I would prefer to lower them, which My power supply does not allow, unless I hover and slowly raise the voltage potentiometer while watching digital ammeter.
I would also take hydrometer readings and terminate charging as soon as all cells either reached their maximum of ~1.280 or simply no longer responded to these higher voltages, accounting for the rising electrolyte temperature, which can make the level on the hydrometer float appear to have stopped rising, until one accounts for the rising electrolyte temperature. The cells in the middle of the battery also get hotter than the outside cells. Bubbles sometimes like to stick to the float and throw off readings.
Flooded batteries intended for cold climates might have specific gravity of 1.310 or higher, those for hot climates might have Densities of 1.265. It is wise to know what the fully charged specific gravity of your battery is when new, for later comparison.
A glass hydrometer is much much better than the plastic EZ red type if one is serious about taking accurate readings, rather than looking for red yellow or green behind the needle.
Francis Freas makes very accurate and Precise Hydrometers, for the anally retentive Bitoger who has temporarily shifted their obsession with Engine oil and filters, to flooded lead acid battery maintenance.
