Partially Dead Voltage Regulator?

 

Last December, her battery was dead and stranded her.  Felt terrible, as I knew her battery at the time was getting old. She was away at college.  A new battery was put in at a dealer.  About 6 or 7 weeks later, car is dead again, only had been sitting about 2 days.  Towed to dealer where they ended up replacing that new battery.  Strange, but happens I suppose.

 

Now here about 4 months since then, battery dead again.  For kicks, I put a voltmeter on it, read 2 Volts, so yeah, DEAD!

 

I put a charger on it, it took a charge just fine, and in turn started the car just fine.  Put a voltmeter on the batter with car running, rock steady 14.5V.  Thinking now I had eliminated alternator / regulator as a culprit....

 

Obviously, something is drawing the battery down.  So I hooked my meter up to measure DC current.  There was a steady .25 to .26 amp draw, which seems high, though I don't know the "spec" on that (and have been looking!).  Pulled fuses one at a time, under the hood and in the dashboard, never saw a noticeable difference. 

 

Check out the picture below.  I should have taken a better centered picture, but this is a picture of the swanky connector on the positive post of the battery.  Upper left had corner is the post itself, which I've cut in half with my mad photography skills.  The ring terminal you see contains 1 heavy red wire.  The small group of flex conduits you see to the right and deeper in are groups of small wires, with several small connectors that connect to the underneath side of the big swanky connector.  So....I'm thinking that big wire goes to the alternator (and is spliced to the starter somewhere).  If I disconnect that big wire, and put the meter in there to check current draw, I get about half of that total draw in that circuit (roughly .125 A)  I get that there's anti-theft, computer, etc. drawing some current all the time, however, what would be drawing .125 amps through that big wire?  Can anyone confirm that big wire only goes to alternator?  Or?  Even though it charges when running, still have a failing diode or something in the regulator?  Can't see it being in the starter motor, as that would not see juice unless solenoid was energized (which would mean it's stuck on trying to start).

 

Thanks for reading.

Well, that would be nice, but that's over 250 miles from here.  They don't "owe" me a lot in my opinion.....The battery replaced in Dec was old enough to warrant replacement.  They then replaced that one under full warranty.

OK, drawing a 1/4 amp even 1/8th amp 24/7 WILL kill the battery..... I'd have to see a real wiring diagram but as you said there are several 'devices' always on even though the key is in your pocket. Being a fairly new car you'll have alarm system, radio, GPS and/or ONstar, infotainment system, remote start system, wirelss door entry wouldn't surprise me the engine computer is 'on' a bit either. If there's an 'insurance black box' in the OBD-II port that draws power 24/7 especaially when reporting to 'them' every so often. A bad diode in the alternator will draw power and kill the battery. Probably 50-100 fuses in the car....if (IF) you pull them all including the 'mains' you should not be drawing any power.

Without the wiring diagram it's hard to say what is the power demon though.

Jay

well it wouldn't surprise me if there's a 3rd box... my 97 F-150 has THREE boxes of fuses....

You might have a corrosion whisker on the backside of a fuse panel. I know certain Dodge trucks have that problem...it actually eats away the stamped conductors in the 'fuse box'.

Jay