I have a Orion smart DC-DC charger in my van charging a 100AH lead acid leisure battery. The leisure battery gets used occasionally mainly for charging phones and other gadgets when on holiday. The van is used frequently and most of the time when not on holiday the leisure battery is not in use and voltage is sitting at around 13v fully charged. I would expect the charger to detect the battery is full and to switch to float almost immediately, but it doesn't. It always goes to the absorption stage after I start the van and switches to float after 30 mins or so. The Adaptive Absorption Time option is selected in the Battery settings.
For long term maintenance of unused battery I read everywhere that float is best, would repeated 30mins at absorption be damaging in long term and would I be better disconnecting?