Hey all.
Hope someone can give me some things to look for.
99 Ford Contour 2.5L V6 115K miles (and in immaculate condition)
Battery was only 2 years old, and alternator was replaced by Ford garage at about 90K miles.

Monday and today, my grand daughter's car has shown a dead battery condition after being parked at her college for 5-7 hours. She indicated it did not even "click" the relays when trying to start. It did jump start OK and drive off no problem.

After Monday's incident she drove it to Firestone where they pronounced the battery dead, and alternator OK. $175 later (new battery, charging system diagnostic charge, and labor to change the battery) she left was on her way home.
Round trip to the college is around 60 miles, and she attends Mondays Wednesdays and Fridays. Wednesday went off with no problems.
Today same thing happened as Monday. Back to Firestone and now they say alternator is bad.
This car has an "Idiot" light for the charging system, and it is NOT illuminated (But does come on with key on engine off).
Headlamps were not left on inadvertently.

Any ideas what may be sticking and drawing the battery down?

BTW, I think Firestone are incompetent crooks. The service manager was drooling at the car and offered to buy the car at a fire sale price. I told her I would kick her butt 9 ways from Sunday if she ever set foot back in that place again..

 

Bad connection especially at the battery can cause just this problem. Everything will appear dead and just wiggling the connection could make everything work again. Could have corrosion down in the cable and need to replace the whole thing.

 

A bad voltage regulator will drain the battery in very short order. They can short internally and keep Field power supplied to the windings when the car is not running. This will not cause the battery light to come on.
Let the car sit for a few hours and feel the alternator. If it's warm, the regulator is shorted.

 

EXACTLY...Technically, the regulator has an "Excitor" wire...mine was my culprit.....The excitor wire is the only one that runs to the dash panel....


Again....Check the alt for warmth......

 

Update:
They put a volt meter on the battery, and it is showing 14 Volts engine running, so it is charging OK.
Sat/drove around town this weekend and no issues starting what-so-ever this morning, and she had no issues driving it to school today.
I am stumped as to what is going on.
Will wait and see if it does it again.

She did get hooked up with a good auto electrical shop about 2 blocks from the school that has offered to look at if if any more issues.

 

The regulator defect that I mentioned usually won't effect the alternator output. It will charge just like it's supposed to. It just doesn't allow the alternator to "turn off" when the engine isn't running, so the battery drains when the car sits.

Nice find on the electrical shop. Those are getting rare these days. I have one locally that gets ALL of my rebuild and electrical parts business. I'll probably cry if the fellow ever retires and closes the doors.

 

14 volts running means your alt is charging, nothing more. What is the voltage going down to when cranking? I have had plenty of batteries that had 13-14 volts running, but no amps to crank. Put a load tester on it and see what happens to the voltage, bet it drops below 10volts.

 

I have also seen a bad starter motor cause a random low/dead battery issue. Might start for days or even weeks with no problem then out of the blue, dead battery.

 

When electrical issues come up, ALWAYS check connections and grounds before buying parts. As someone else mentioned, clean the battery terminals. My F-150 and VW bus both had a tendency to corrode them often, resulting in a no-start even with a charged battery.

 

Diode problems.

 

I would loosen and clean all contacts from the battery to ground to the starter and trace everything back to the alternator.