Originally Posted by slonecker
..nothing running except the detector?...
What detector? CO? Propane
? What is the power draw? You can usually find the power draw on the unit or in the manual.
OEM battery or upgraded? How old?
CO detectors usually run on internal batteries. Propane
detectors usually run from the trailer battery and draw much more power than a CO alarm although that amount does vary quite a bit from model to model. And there are combined models.
For my propane
alarm, if I leave it on I would charge my 100 Ah battery up every two weeks.
But just pull the fuse for the propane alarm or better yet disconnect the battery neg wire or install a battery disconnect switch for convenience and safety. Then the battery will go for months before internal self-discharge is a concern. Still at least one battery manufacturer recommends topping off a battery "in storage" once a month. For lead acid batteries they will live longer if kept fully charged so thats good advice.