Originally Posted by Teej
I do achieve a full charge when I recharge with a reading of 100% capacity if I can believe the battery meter on the electrical
panel, which displays voltage, amp draw and battery capacity for both the house and starting batteries.
With your admitted "hour in the morning and hour in the evening" charging protocol your meter is not to be believed. There is virtually no way you are recharging to 100% in just two hours per day of engine run time on a 600 Ah bank. The bad cells could be tricking your battery monitor or it needs to be re-calibrated.
The last 10-15% of charge takes hours and hours to replenish due to battery acceptance not just a couple this is why cruisers often cycle their banks between 50% & 80% state of charge. Also, due to charge inefficiencies, even when putting back 100 Ah's used it may take you 120 Ah's returned to replace the 100 Ah's you used not 100 for 100. You may be getting back to 70-80% SOC but probably not much more with just 2 hours per day of charging.
The most your banks will even accept when very low is in order of roughly 120 amps of charge current for a 600Ah wet cell bank. If you drew your bank to 50% state of charge you would need to replenish the 300 Ah's to be at 100% but this maya lot more than 300 Ah's to get back to 100%, and lots of time.
Two hours of run time would barely get you back to 80% even if you had a 150 amp or 200 amp alt. At about 80% SOC the batteries would begin accepting less and less charge current until they are accepting roughly .5-2% of the banks entire capacity when near full. So while at 50% SOC you may see 100 amps flowing at 90% you may only be seeing 12 amps and at 95% only 5 amps and at 98% only 2 amps and so on. (not exact number just an example)
You are likely chronically undercharging your bank due to an out of sync monitor giving you erroneous information, bad batteries and your minimal re-charge times of just 2 hours per day.
12.2 volts, if measured correctly, with a true resting voltage reading, is only about 60% state of charge. So perhaps your out of sync monitor is also allowing you to draw your bank deeper than 50% depth
of discharge and your not even getting back into the 80% SOC range with your two hours of charging.
The best measure you can use with an out of sync monitor is to monitor the amps flowing back into the bank. If your monitor is telling you that you are at 95% and the bank is still accepting 60 amps then your are NOT at 95% SOC. In order to be anywhere near full there will be very little current flowing back into the bank. When you are seeing amps flow at less than 2% of the banks 20 hour Ah capacity then you can consider your bank near fully charged. Don't go by the "fuel guage" on your battery monitor if you suspect it is out of sync. Instead use amps flowing as a rough measure of state of charge. Lots of amps flowing means not full, little amps flowing means near full..