Originally Posted by Maine Sail
This is good the D400 is a beautiful piece of gear. Keep it! Or, on second thought, give it to me...
I suspect your battery monitor has become out of calibration? A battery charger only "goes into absorption" when the absorption voltage has been attained at the current available.
If you are hitting absorption this means the batteries have finally come up to absorption voltage. If they are sulfated this can happen well before it should but its not really the chargers fault.
The biggest problem with many chargers is the absorption stage is rather dumb, or not as "smart" as they market it, and goes into float prematurely for many banks. Often times they are simply timed from when absorption voltage is attained and after a set period the charger drops the voltage to float level whether the bank is at 98% +/- SOC or not...
Getting back to 100% SOC will take about 10+ hours as the batteries are accepting less and less the fuller they become. The last 5-10% takes hours... The only way to speed up absorption charging is to boost the absorption voltage.
I have suspected my batteries have become fairly heavily sulphated and your explanation of why the charger goes into absorption just confirms my suspicions. It got me to wondering if the reason I'm not getting as good charging from the D400 may also be related to the sulphication as well?