Herk has already answered the question.
most campers have a Lp detector and clock, so using Herk's estimates that's 400milliamps.
400milliamps = 0.4Amps
A typical group 24 battery has about 80Amp Hour capacity
Generally you should try to keep the charge above 50%
So, 40 amp hours / 0.4 amps = 100 hours which is just over 4 days.
Complete discharge in 80 / 0.4 = 200 hours = 8.3 days.
Each situation will be a little different depending on exact load on the battery, battery size & condition, etc. But a dead battery in a week and a half should be expected. To keep your battery in tip top shape, you shouldn't let the charge drop below 50%, so disconnecting the battery when not being used is important, even if it's only for a couple days.
Originally Posted by herk7769
There are several "parasite" draws on our camper's.
The Propane detector has a heater in it that ionizes vapors to trip the detector. It draws about 300 milliamps continuously as long as a battery is connected to the camper.
The radio has a clock in it that requires power to run. It draws about 100 milliamps to do “keep time”.
If you do not “turn off” the radio, it will draw about 2 amps, so I assume you are doing that.
The only way to isolate your battery from the camper is with a disconnect switch.
One half an amp will kill an OEM Dual Purpose Camper battery in two-three weeks.