If you decide to leave your batteries over the winter (without SOLAR or battery charger), make sure you leave them with a FULL charge and proper water level. Then disconnect
ALL the battery cables from the batteries, even the ones that connect the batteries together. This way there is "ZERO" resistance on the batteries, and if for some reason one of the batteries happens to go south (very unlikely), it will not affect the other. They should do fine over the winter.
PS..... If they are old or have not been maintained properly, take them home.
Don
My Registry
RVing with SOLAR