@DannyP posted:That would be what I recommend as well, whether or not the device remains.
Float chargers(not to be confused with trickle chargers) are the solution. Plug them in and forget. I have one for my Spyder, my BMW R100, my Cayman, and for my car trailer. They are all hooked up for the winter/non-use months.
Float chargers can be had for $20-30 dollars each.
Float chargers apply a continuous voltage to the battery, albeit at a level lower than the alternator, just high enough to keep the plates from sulfating. They don't work well with maintenance-free batteries, which have a finite supply of irreplaceable electrolyte. The water slowly boils off, eventually exposing the plates to oxygen, which causes the battery to fail. Float chargers do well with maintenance-accessible batteries, where lost water can be manually replenished. They also do well with sealed, recombinant VRLA batteries.
For maintenance-free batteries, I either use a maintainer-desulfator, or I simply put a timer in front of the float charger so it only runs for an hour each day, which is just enough to boost the battery to a full state of charge. If your vehicle has small parasitic loads, increase the timer's duration to 2 hours.