If you’re storing your Bronco long-term, a battery tender will keep it charged and ready to go. The Battery Tender brand, by Deltran, is the best known in the industry for good reason. Their products are lightweight and compact, but also have smart features. They switch to a “float” mode after the battery is fully-charged, reducing electricity use and avoiding any damage to the battery.
You may want to add a second battery with a dual battery system from Painless Performance. This lets you power any accessories you have on your truck, such as off-road LED lights. Or, get their extra-long extension cables to move your Bronco’s battery to a new location. You might need to do this if you’re adding larger engine components or performance headers.
To be prepared out on the road, a nitrous-powered battery jump starter is a great tool to keep in your Bronco. It'll allow you to jump your battery without having a second vehicle around.