You need to know what your parasitic loads are and you already may have damage to your batteries depending on how far they have been discharged. If below 50% SOC (state of charge) some damage has been done!
The only way to assure that the only drain is internal to the batteries is to pull the negative batter terminal(s)once batteries are fully charged. I installed my cutoff switch and the only load when that is off is the Victron battery monitor. I alos chose an AGM battery which has a much slower self discharge.