Charger or converter?

I've got a cargo trailer w/30amp 120vac. I'm adding a size 24 battery to power a 12v water pump for a sink only, no shower. And a winch. I'm trying to figure out if I should get a converter, battery charger, or battery tender?
This is a competition BBQ trailer that will be used about 36 hours at a time with occasional use of the water pump during that time and maybe 3-4 minutes of total use time on the winch. While trailer is in use it will be connected to shore power.
Help is appreciated!
This is a competition BBQ trailer that will be used about 36 hours at a time with occasional use of the water pump during that time and maybe 3-4 minutes of total use time on the winch. While trailer is in use it will be connected to shore power.
Help is appreciated!