It is likely the previous owner pulled the fuse to disconnect the battery. You will want to somehow disconnect the battery when you are not using the camper for more than a few days. This will prevent discharging the battery by the alarms and significantly extend the battery life. Lead acid batteries do not like being discharged more than about 50%. You can pull the fuse, disconnect a battery lead, or install a disconnect switch.
2014 Eagle Premier 361REQS
2013 Ford F350 Crew w/ 6.7 diesel