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Battery Draining - short?

S

sk8token

CEG'er
Joined
Mar 19, 2002
Messages
83
Location
Tucson, Arizona
For a few days leading up to today I could hear that the starter wasn't getting the amount of juice it normally gets, the car would turn over more slowly when cranking. I knew it was about to give me issues, and today when I went to start it I just got the clicking sound up front.

With the battery connected to the car, engine off, doors closed (everything off basically), I'm getting 11.12 volts across the battery posts. I pulled the negative cable off to see if the voltage would go up, and it went up to 11.5 volts, so I think I have a short somewhere putting a load on the battery while it's just sitting there. First thing that hit me across the face was the thought "Oh god, I hope its not the F'in underhood harness"

Car has 150K miles and original alternator it appears.

Just the other day it read 12.22 volts at rest and 13.7 volts at idle, and 13.3 volts at idle with the a/c on max high fan. Seems weak, I usually see 14v or above.

Is it possible for the alternator to short out, or when it goes bad, cause a draw while the car is off? On my 70 Mustang I had an alternator that had a diode go bad and it would just run the battery down while sitting. It would also make the battery posts so hot you couldn't touch them, but the Contours terminals are cool with everything connected, so it's at least not as bad if it is the same issue. I really hope its not crossed wires in a degrading harness!

Am I correct that I shouldn't be seeing a .5 battery voltage difference between cables connected and cables disconnected?

Thanks for any ideas!
 
I'd have the battery tested. I think the voltage light would be on if the alt. was bad.

My original Motorcraft battery went over 160,000 miles and I replaced it with an Interstate battery... cranks over much faster!
 
How old is the battery? If it is more than 5 years or 100K miles, I would just change it rather than messing with charging it. I just changed mine two weeks ago, when I saw some corrosion on the battery holder. Mine was 7 years and 55K miles (it was showing 12.10 volts).
 
The battery is about 2 years old now. I think I'll charge it up and bring it over to a parts store and have them test it. If that checks out, I'll take the car over there and see if they can find anything with their charging system tool.
 
Just reread your post. 150K miles on an alternator? Might as well change that too. After all, that is a "piece of cake" for the Zetec. ;)
 
Tony2005 said:
Just reread your post. 150K miles on an alternator? Might as well change that too. After all, that is a "piece of cake" for the Zetec. ;)
Click to expand...

Tony, can't tell if you're serious or being sarcastic :) Seems like it would be easy, but if it's anything like the water pump/timing belt I might have to just light the car on fire haha
 
sk8token said:
Tony, can't tell if you're serious or being sarcastic :) Seems like it would be easy, but if it's anything like the water pump/timing belt I might have to just light the car on fire haha
Click to expand...

:laugh: ROTFL. Not sarcastic, just letting you know it is probably 10 times easier changing a Zetec alternator than changing a Duratec one. :crazy:

And no, I guarantee you changing the Zetec alternator is not like changing out the water pump/timing belt. :)

Edit. Look at the Autozone link. You don't even have to remove the wheel or outer tie rod. And some CEGers do not even have to jack the car up to loosen the belt.
http://www.autozone.com/servlet/UiB..._us/0900823d/80/1b/c3/18/0900823d801bc318.jsp

And if you suspect the Voltage Regulator is at fault, which doesn't appear to be in your case, you don't even need to remove the alternator from the chassis. Just remove the bolts holding it down, then pivot it out and you can change out the VR. Read this link from the old forums from DPDISXR4Ti
http://www.contour.org/ubbthreads/s...d=allposts&Main=979000&Search=true#Post979837
 
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Well, as an update, I went out and measured battery voltage again, now that the negative terminal has been disconnected for some time now. Voltage now shows 11.85 (voltage is 11.12 when terminals connected and car is just sitting). With the voltage climbing back up like that when the load (from the car just sitting in the driveway) is removed, my gut tells me the battery is probably ok and there is a short somewhere.

I wonder if I'll be joining the recent wave of harness replacers?
 
Last edited:
Fixed... Bad Battery

Fixed... Bad Battery

haha it turns out it was the battery, at least that's how it's looking so far. Put a new one in and with engine idling I'm getting 14.3 volts across the terminals... looking good there. Also tested the battery voltage with negative terminal connected and disconnected and the difference in voltage readings is now negligible.

I think I keep waiting for the wiring to become an issue so I can get in there and deal with it already... don't want to get surprised by it on a long trip, that's for sure.

Thanks for the help guys!
 
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