Do you have a DC amp meter?
If you do, you can measure the DC load by removing the negative wire, then connecting the - cable to one lead and the other lead directly to the battery. Say it gives you a 0.8 amp load, and you hear the CO meter and propane detector beeping that they just got back power. You know that both of those had power restored, and might be the loads you are looking for. By shutting off the propane detector, your load might go down to say 0.4 amps, indicating you found one load, the other probably being the CO meter that can not be shut off (for safety reasons).
If the load is over 5 amps, then removing one circuit breaker at a time can help locate the problem. Because you can not remove the fuse, like a typical load panel, you might need to remove one wire from a circuit breaker at a time until the load goes away.
If your "Problem" is that while not plugged in your 220 amp hour battery is totally dead in about 4 days, then the "Problem" is the CO and Propane detectors together use that much power, and it is really not a problem that can be fixed. Better to just add a 120 watt solar panel, or keep it plugged into shore power, and then you will keep the battery full that way, and will solve the problem.
Sears has a clamp on DC amp meter. With it, you can clamp it around one wire at a time, and see about how many amps are being used by that wire at one time. It is a easy way to measure the DC amps. it is about $80 - $100.
Good luck,
Fred.
