Cold is the enemy of an idle battery. Put a charger on it a couple times through the winter and as aforementioned keep it in a warm environment . If it is lead acid non sealed type ensure charging is done in an area where there is adequate ventilation, since the old style batts off gas (nasty stuff) during charging as opposed to sealed AGM batteries which do not. This makes me wonder why MOPARS had batteries mounted under the seat. A slow charge setting is always preferred to a fast charge to prolong it's life. Hope this helps. M