The LP alarm is wired directly to your battery........but if the battery 'disconnect switch' is turned off the converter cannot recharge/maintain battery voltage.
Also under you kitchen sink and bathroom sink are 'air admittance valves'. They are air check valves installed downstream of the 'P' traps so that when you drain your grey tanks the line suction from draining doesn't suck the water out of the 'P' traps (air admittance valves open allowing air into the drain line to grey tank). If they are old (the rubber flapper gets weak/less flexible) they can not properly close and grey tank odors can come inside your trailer.
Any hardware store a will have them......just replaced mine (7 yrs old). $2.50 at Home Depot