Will not start.clicks only with charger on.

LOL! The odometer is a new one on me. Anyways, battery charger or battery charger with boost capabilities? After sitting for 5 months an older battery can totally lose it's charge and is a possible indication the battery is on it's way to where batteries go when they give up the ghost. Applying a battery charger without boost capabilities usually, in my experience, requires that the battery needs to be brought up to a certain voltage before attempting to start. Even boost chargers will display this on occasion too and some like my smart battery boost charger won't/can't connect to and start charging a battery with less than 1.5 volts.