My house batteries are bad and I plan to change them out this spring our upcoming trip has full hookups so I won't be on battery power. I will look to see if the house batteries are charging we had a power loss the other day and it may have tripped the charge circuit off. There is a button on the inverter that turns battery charging on and off so it maybe off after the power outage. The detector is just hanging from the ceiling right now because they did not leave enough wire to unplug it if I change it out I will need to cut the 3 wires and splice on a new detector. I will look for a date on it but I think it is original equipment and this is a 2005 so it probably needs changing. I have an LP detector also but it is down close to the floor.
For a replacement does it have to be an RV type they are much more expensive. I like the idea of it having its own battery and not rely on the house batteries.