It took me awhile this season to figure out what was causing this. Most of the time we would get to the river the night before, take the boat out the next day, clean it, put it in the garage, and then leave.
Several times though, we would hang out at the house after putting the boat up or even stay the night and the smoke detectors would randomly go off.
We had replaced several of them before I realized that if I didn't plug in the charger for the boat (Xantrex 40A TruCharge 2), the smoke detectors would not go off. The smoke detectors are hard wired, FYI.
Anyone have any insight as to why this might be happening?