It means you overloaded the battery with two much current, either in charging current or with the load current. Sounds like the batteries are fried (literally).
so what do you think i could be? because im using a 12V 20A lighted toggle switch and its powering a 12 volt fan, could it be the wires im using? 18 gauge for the most part except from the actual battery pack. could it be the connector to the battery pack? its a 9 volt connector. the pack houses 8AA batteries.
It won't be the wires or the connection. Do the batteries get hot while operating the fan, or while recharging? What kind of batteries, NiCad, Nickel-Metal-Hydried, Lithium? What kind of fan? What is the fan current?