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

[Random_Stranger]

Ok So after disconnecting the obvious, the car alarm, I find it still draining. I noticed with car running on this "New" alternator, it bumps up to 17v which is not normal right? Ok so I after reading that sometimes a bad alternator can drain batteries, even if they do recharge the battery when the car is running, I decided to try that out.


I disconnected the alternator with the car off while I was watching the battery being drained. Wouldn't you know it? The drainage stopped after unplugging the wire that connected to the top of the alternator when installed, secured by a nut.

So here's my new question. Could it be the wire or is it the alternator itself? I noticed the wire is getting that green rust on it, but I dunno where it all goes to in order to remove the whole thing to clean it. Any suggestions? Could it be in fact the alternator? Even if it is the wire, I wouldn't know how to go about getting a new one other than just cleaning it, but that would require me to break off all that plastic coating from around the wire to get to everything. But even if that has rust, would that drain my battery from the alternator?