Trailer wiring help

Hi All,
I have a new trailer that I have installed a winch on, and a batter to power it. My question is;
The truck (2014 ram 2500) has a terminal in the trailer plug connector that seems to be a 30a circuit back to the fuse box. If I continued that power feed from the connector to a mechanical 30 min. twist timer, and then to the battery, could I feasibly, (without damaging the truck) charge the battery when it gets low? Rather than have to always have a gen and battery charger on hand?