1984 Volkswagen Jetta Problem with battery draining

Tiny
VWJOJOVW
  • MEMBER
  • 1984 VOLKSWAGEN JETTA
Electrical problem
1984 Volkswagen Jetta 4 cyl Front Wheel Drive Manual 180xxx miles

hello my name is Joseph and I own a 1984 Volkswagen Jetta with a 1.6 liter diesel engine. When my dad gave the car to me, I noticed that the battery light is on every time I start it. When I rev it up, the light goes away. I later discovered that the alternator is actually charging my battery. I tested using a battery charger. With the car not running, the battery was 75% charged. After 20 minutes running the car on neutral, I turned off the car, disconnected the battery from the car, used the battery charger and the battery was over 90% charged. Right now every time I'm done using the car, I disconnect the battery so that my car can run tomorrow morning. Is this bad for my car? And do I have an electrical short or is it the alternator taking power from the battery while the car is off?
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Saturday, December 19th, 2009 AT 5:16 PM

5 Replies

Tiny
DIESELLOVER
  • MEMBER
Hmmm, you don't give us much to go on. How old is the battery? You did clean the posts and the insides of the cable connections for 100% connection? Did you install a new radio/cd player with detachable face? If you don't disconnect the face, it will discharge your battery overnight. Do you have a multi-tester? If so, disconnect your battery cable and put the tester in between the cable end and the battery post. If your car is discharging it will show on the meter. Be sure all extra lights are off. Glove box, dome light, etc. Hope some of these suggestions are helpful to you.
Tom (I have '82 diesel Rabbit and two diesel Rabbit pickups all hopping along fine) : )
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Tuesday, December 22nd, 2009 AT 2:30 PM
Tiny
VWJOJOVW
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The battery is fine. I found out that my car is taking away power when my car is off. It cant be any of my electronics or my A.C. Because all of them are turned off and I always take off the face from my stereo when I leave my car. What can I do to track down the thing that is draining the battery? I want to solve this myself because I heard labor on repairing a Volkswagen will cost me a ton of money. Please help.
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Friday, December 25th, 2009 AT 12:46 AM
Tiny
DIESELLOVER
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With the engine off, ignition turned off and key removed, and NOTHING electrical on to your knowledge, remove the negative battery cable from the negative battery post. Then connect a test light between the battery and the cable. If it lights up, then something is draining the battery. Go to the fuse box of the car and one by one, remove and replace the fuses until the test light goes out. When the test light goes out, you isolated the area where the drain is coming from and you'll then have to inspect whatever is on that circuit for a bare wire or somthing that is causing the drain. Good luck and I hope that helps! Merry Christmas to you and yours!
Best wishes, Tom
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Friday, December 25th, 2009 AT 7:19 AM
Tiny
DIESELLOVER
  • MEMBER
Joseph, just had an afterthought that you don't want to overlook as a possibility. With the miles on the car, is the alternator original without any extra attention given to it? If so, it might need new brushes. These are not expensive and "easy" to replace. They make contact with the turning armature inside the alternator. With use they gradually wear down until they barely make contact with the armature. This will produce charging current at high rpm's but in start/stop town driving and low speeds, don't produce enough current to charge the battery and radio, headlights, brakelights, ac/heater blower, etc, will discharge the battery w/o the alternator recharge. Just something little, but that's what you're looking for that's causing your battery drain. Good luck and Merry Christmas! Tom
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Friday, December 25th, 2009 AT 7:45 AM
Tiny
VWJOJOVW
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Thank you Tom, and Merry Christmas to you also!
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Friday, December 25th, 2009 AT 2:48 PM

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