Battery & cut off switch

Probably the propane/CO detector. Generally, they are wired in so the battery disconnect does not affect them. Also, the radio most likely always has a slight battery discharge going to it.

Most rigs will last a bit over a week without some type of battery charge. Best to do as you did - disconnect one of the wires from the battery or put a switch between the wire and the battery.
Barney

My switch.

Ad a modest solar charging system.

SO, disconnecting the neg cable does the trick?
If not then maybe the battery is so near the end of its life that a week is all it takes for its last remaining amount of power to naturally drain out.
Batts lose power always when sitting. A god battery will not matter if it loses a little, but a near-dead one will.

If it is still draining this fast and is not an old battery then there is more than a CO monitor pulling down power. A short might do it. It could be anything, even a solar panel that lacks a proper diode.

Is there a fantastic fan that comes on when it gets hot that you are not aware of, or something like this that might be off when you are in it closing up, but then comes on when you are away?

OK, thanks all.
The battery is only a year old, so it should be good.
I thought the propane detector would be wired on all the time, but did not think of the radio as Barney suggested. I will check that.
There is no fan that comes on that I know of.
My next plan is to go into the fuse box and pull a fuse or 2. There is just so many things on this rig that it could be. Each storage area has a motion light that comes on and should go off when the door is closed. Those are noted for not shutting off. It I can't find it I will get one of those cut offs that attaches to the battery terminal.

Shut odd everything that you normally have off when your rig is in storage. Try pulling fuses one by one. After you pull a fuse, use a good quality digital ammeter to jump across where the fuse goes to find out which circuit(s) has a power draw.

Shut odd everything that you normally have off when your rig is in storage. Try pulling fuses one by one. After you pull a fuse, use a good quality digital ammeter to jump across where the fuse goes to find out which circuit(s) has a power draw.

Thanks for that curt. I didn't think about that. I was just going to pull a fuse and check in a few days.
I always shut off the factory installed shut off switch, but the battery is still going dead in about 8/10 days. So I'm pretty sure there is more drain on it than the propane alarm and the radio that is not on, but I know they do draw some current to keep the channels set etc...

You might start by seeing how much draw is between the battery positive terminal and the cable going to the battery, before starting in the fuse box.

Is there anything that pulls off the battery before the fuse box (electric jacks, slides, etc.) or anything that was added after it was built?

Don't assume a new battery is good, have it load tested. Suspect everything.

Clampon ammeters are an extremely useful tool for RVs.

There may be more items that don't shut off or on standby with the switch off than you are aware of.