Car drains battery when off

I have a Ford Festiva GL 93' and the car keeps draining the battery at night. At first the car didn't hold a charge and so I checked and replaced the alternator with a used one. I had the alternator checked and installed it. I just gave it a tune up and recieved a new battery to put in it. The car runs good now with the new tune up and all but I can't figure out why when I leave the car outside at night the next morning the battery is dead. I checked the lights and I took the light bulb out and pulled my switches for the back lights and so I have no lights at all. The voltage regulator is in the alternator and after talking to several people they have told me that even if the used alternator was bad that it couldn't drain the battery over night and that my car must be running somthing when it's off.

Reply to
Ikky Sleepy
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Reply to
Mike Behnke

Ikky Sleepy wrote in rec.autos.tech

The voltage regulator is in the alternator and after

Most likely something, such as a light, is staying on. Not greatly familiar with the car, but do you have a trunk? If so, the bulb in there could be bad. As far as the voltage regulator goes, I had a car that had a bad regulating transistor in the voltage regulator. When running the alternator and regulator would charge just a bit low, but when I turned the engine off the bad transistor would bleed the voltage down to 12.4 volts in minutes. And that meant that I would either have to get a jump, or roll down a hill (stick shift). What I did was to disconnect the negative cable from the battery when I parked. Replaced the regulator and all was fine. I found it by starting the car, reading the output from the alternator with a DMM, and then shut off the car and read the battery. I could see the voltage drop to 12.4 volts in about 2 minutes.

Reply to
Dick C

If you don't know how to check out the charging system with a meter then take it to someone and pay them to diagnose it for you A defective alternator can discharge the battery. Was the battery new or just new to you. Anything can be causing the problem and you can guess and replace parts until doomsday and not fix it...

Reply to
Woody

The alternator was used from an 88 festiva. We checked the voltage when it was on and it red 12 v and the bad read 12 v. I checked each fuse and they look good. I'm probably going to let my bro mess with alterntor cause he said he can fix it and did it before for one of our trucks. There is no light in the truck... there is nothing really connected to it that I could see. I disconnect the negative terminal when I leave to school because after like $x amount of hours it drains the batter.. last time it was 6.

Reply to
Ikky Sleepy

You jump a light bulb from the ground to negative battery. Remove the battery neg. cables first. The light should be dim if normal. If bright, disconnect the alternator wiring or continue with one fuse at a time or pluck each light bulbs that don't come on that normally should.

The theory behind this is that a short will make the bulb bright and a non-short will glow dim.

Replacing the alternator is not a bad idea, but it would be a better idea to remove the connectors on the back of the alternator overnight. But check the diagram - this isn't a sure fire diagnostic.

-- Milo

Reply to
Indiån §ummer

News Flash! If the alrernator read 12V when on then it is bad.

Reply to
MaxAluminum

News Flash! If the alrernator read 12V when on then it is bad.

Reply to
MaxAluminum

AutoZone checked it for me and about the 12 volts.. my friend checked it. I am going to try to disconnect one of the cables from the alternatdor @ night and try that technique and on the weekend I am going to take the alternador out and try to check the voltage regulator and have it tested again,meanwhile since i'm broke, i'll disconnect the battery terminal each time I go to school.

Reply to
Ikky Sleepy

It would be a pain to remove it each night, I'm not saying you're suggesting this.

Again, diagnostically remove the cables. Connect a light bulb from ground to an unconnected negative battery terminal. Remove the alternator cables. Light goes from bright to dim ~ bad alternator.

Personal thought: Learning simple tricks of the trade is free.

-- Milo

Reply to
Indiån §ummer

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