Originally Posted by Max@MaxTyler.US
Thanks for the additional explanation.
We were discussing making a cut-off which would be based on the SOC.
I am curious about the details of what you have in mind.
An AGM battery needs (energy to charge at room temperature) + (energy to drive the reaction when not at room temperature)
The typical multi stage charge profiles that you see published are for room temperature conditions, and the battery needs to be fully charged, ideally every time, but at least fairly often in order to work properly.
When the battery is cold, additional energy (in the form of voltage) is needed to make up for the lack of thermal energy. This is the whole point of temperature compensation - raise or lower the voltage as needed, depending on temperature.
In cold weather, these voltages can rise substantially - 16 volts is not uncommon.
Are you thinking of an algorithm that uses changes to the finishing stages to make up for the lower bulk charge voltage?