Tank heaters

They probably are. killing your batteries If there is no switch, I'd put one in right away.

Facon heating pads book says they turn on at 45 degrees and turn off at 68. I haven’t used the rv for a month and the batteries were dead even with small solar charger. But its been getting cool.
Thought maybe the pads are sucking the battery down

Didn’t get a spec sheet maybe I can call the dealer

If they have actual heading pads I'd think you'd have a switch some where. Mostly RVs that have enclosed underbellies allow some of the heat from the heat ducts to heat the space. Was it listed on the spec sheet when you bought it?