propane/co/fire/smoke detector

I buy my fire/carbon monoxide detectors at Big Box stores. I suggest buying a carbon monoxide detector with digital readout - the other ones are like the idiot lights in a car which always leaves you wondering how serious the problem is. I move our carbon monoxide detector into the stick house when the RV is stored during winter - does double duty. I am unsure whether you can find a propane detector that runs on std double A batteries - be interested to see if others have found one.