My CO/propane detector has been going off when the battery goes low, so I replaced the battery which was totally dead, after three years. After I replaced it, the CO detector kept going off, which seems like it's running the new battery down. I've been checking the battery strength after I put it in and it keeps losing strength. Could the CO detector be running down the new battery. The RV is not in use right now, so I'm plugging it into my garage outlet so the battery doesn't keep running down and the CO detector goes off. Or could it mean that the CO detector is getting old. It's only three years old and the green light is on.