This is a bit of an old thread, but is the first hit I got on the subject of propane detector false alarms. I have a Lance 1050S truck camper, with the batteries in a compartment inside the cabin. The propane detector is mounted on the wall of that compartment. The batteries are each in plastic boxes vented to the outside. Under certain wind conditions (wind from the front, rear door open), hydrogen gas from the charging batteries is forced back into the compartment via various leaks in the plastic battery boxes (mainly where the wires exit), and into the rear of the propane detector, causing it to alarm. I verified all this with an Amprobe flammable gas sniffer which I used to search for the "leak" causing my alarm to go off. The largest reading I got was directly in front of the propane alarm, till I opened the battery compartment and checked where the wires exited the plastic boxes--that gave an even bigger indication. So add "charging batteries" to possible causes of false propane alarms--it was definitely my problem.
