Charging your battery between trips depends on how long between trips.
I take my battery out if I know it's going to be over 4 weeks, before going out again, on many caravan there are " hidden " power drains for the battery. ie, the alarm , the fridge control panel, the TV booster, the radio in the van etc.
If you have a solar panel then this will charge your battery.
I do tend to disconnect the battery every time I leave the van in storage as the alarm has its own power supply.
Depending on how "dead" your battery is you might get away with just recharging it, I managed to resuscitate my battery once, it was below 9 volts,
I have a
Nexpeak battery charger which has a recovery mode.
Woodentop asked a good question, about the battery actually being flat, as I had the very problem he pointed out, the battery in the hand controller was flat.