Flickering or pulstating Headlights

The battery is the only thing I've changed in the electrical system since the last time it was running and I'm pretty sure it has a dead cell, last winter I took it out of my Jeep to put in a new one since it was losing a lot of charge overnight in cold outside temps... I've been keeping it on a battery tender when the Duster is sitting in my garage and it starts up fine but I know the charge capacity of the battery is really low. I guess I'll go ahead and replace it first before other troubleshooting since I need a new one anyway.