Usually a low voltage beep will be the propane leak detector. Nothing else beeps on low voltage in our trailer.
An inexpensive LCD voltage meter is so very useful for anyone who boondocks. I wish they were standard equipment right there in the trailer control panel. But it is super easy to add one yourself. Get one that will read in hundredths of a volt, 12.xx. Wouldn't you like to see what voltage is setting off the low volts warning, without going out in your skivvies, digging out a meter, and opening the battery compartment?