Haunted?

I dreamt last night that I was in a house (not mine), going to every smoke detector and carbon monoxide detector, trying to figure out which one was beeping and needing a new battery.  It was fruitlessly frustrating.  I gave up and decided to take a shower.  Unfortunately, the shower was already running (very hot, as the closed, bathroom door felt warm, and there was steam seeping out around it).  I walked into the bedroom and saw the (late) actor Paul Walker doing something (folding laundry, painting, something).  He said he was letting the shower warm up.  I left the room, unsure of how to while away the time until he was done in the shower.  That's when Paul had his "aha! moment".  "Wait.  I'm not running the shower, and if Cap'n isn't running the shower, and I'm not running the shower, who is?"  He went into the bathroom and discovered the body of his father, who had committed suicide.

"Well, isn't that a pleasant dream!" I thought, and I woke myself up.  Then, I heard a beep.  In real life.  Argh!  I went into the hallway, stood directly in front of the carbon monoxide detector, and waited for the beep.  Aha!  I took it into the bedroom, turned on a light in the bathroom (so as not to blind myself with direct light), and... heard a beep from the hallway.  Not from the device in my hands.  Razzlefrazzlesnarfin'...

The one thing that went right in all this is that I'm tall enough to reach the smoke detector on the ceiling, so I didn't have to hunt for a stepstool in the dark.  I took down the detector and walked to my bedroom.  The detector I was holding beeped.  I removed the battery and left it and the detector on the bathroom counter, as a reminder to replace the battery in the morning.  (Never fear, loyal readers!  There remained a hard-wired smoke detector in place, should anything worse happen overnight.)

I decided that, since I was already up, I'd go to the bathroom.  The detector beeped.  Yes, it beeped without the battery in it.  As I washed my hands, the detector beeped again.  "All right, you!  You're going down to the kitchen tonight.  You can beep all night long, and I won't be able to hear you from there."  Naturally, it didn't make a sound as I took it downstairs.  I left it (and the battery) on the kitchen table anyway.  (I did insert a new battery, test it, and carry the detector back upstairs, after breakfast this morning.)  It took me more than a half hour (based on the grandfather clock) to fall back asleep.

In the name of all that is good, why is it that the batteries in smoke detectors never run down while I'm awake and able to do something about them?  And how did this one continue to beep after the battery had been removed?