I NEED YOUR INPUT/HELP! PLEASE, Can an alternator drain a battery with car off? Options

[Random_Stranger]

Ok so I have this issue where my car battery is suddenly being drained by something. I was just wondering what first things to look at. Also what I find strange is that it didn't want to start last night (I witnessed a hit and run across the street, thought the guy was gonna stop but when he took off, I was going to jump in my car and get his license plate number, but my car didn't start). So I busted out the voltmeter and seen it was like at 9.38v. I set my alarm and went inside and later that night, I hear my alarm chirping in a way I never heard before. Then it got louder, and louder and then just went off making it's normal sound if someone attempted to break in. So I go out there and disarm it. Noticed my lights were dim and checked the reading again. It was 7.38v. I left the voltmeter connected to it and sat in the car wondering what it could be. I went back and noticed it climbed up a bit to 7.44v. I let it sit there and watched and it climbed up to 7.48v before I just disconnected it.

Is that normal for a voltmeter to do that? You think it might be my car alarm? I have an optima battery which is like 3 years old. Not sure what the life expectancy is on those or if maybe it is in fact something draining power.

This post has been edited by Random_Stranger: Jan 9, 2012 - 4:39 PM