Most likely that is the LP Detector going off on low battery.
It is wired DIRECTLY to battery so that it is ON....safety device to WARN you of a propane leak so you do not continue 'sleeping' and not wake up
Unless you remove ALL propane devices, lines, tank etc then disabling a safety device is NOT recommended.
Need to FULLY Charge battery during DAY Time hours so that battery voltage doesn't go low during night time
Solar Panels OR longer generator run time ----running engine won't do it
Besides..constantly running battery down will damage them (below 12.3)
Probably reason yours doesn't make it thru the night
