It depends on several things
Open lot: Solar may work, Make sure you have a properly programmed controller
You have power in the storage facility: Your converter.. if you have a good quality converter like any of the Progressive Dynamics Wizard models this is #1 on the good idea list.. Just plug in.. In my case I can plug in JUST the converter if I wish to make sure I limit current draw.
If you have an older rig with say a Magnetek 6300... NOT a good idea
If no power in the storage lot and solar not an option
First, using a small can of RED spray paint (Testors is good) Spray down the positive wires on the batteries... Use Black on the negative.. now photograph and allow to dry
Remove batteries to a place you can store them WITH POWER
Set them on a slab of scrap wood (Reason in a minute)
Use a "Battery Minder" or "Battery Tender"
Why set 'em on scrap wood
MYTH: Setting on concrete will damage the battery... Well perhaps once but not today
Truth: Setting on concrete MAY damage the concreate, if the battery leaks a bit a floor is expensive to replace, be it Con create, Wood, Vinyl or other. (Cermaic or glazed clay tile is usually fairly hard to damage)
Scrap wood on the other hand.. Is very very cheap (Definition of SCRAP) and thus easily replaced at no cost.
