# ok when car running constant loss in battery volts



## proudvwrabbitowner (Sep 3, 2008)

????? could it be the alternator 1980 vw rabbit typle l fuel injection


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## pimpbot (Jan 9, 2006)

*Re: ok when car running constant loss in battery volts (proudvwrabbitowner)*

I had this issue. As long as my '96 was running, it charged and would run forever, although it seemed like the engine was under more load than usual at idle. Once I turned it off, the battery would start draining like crazy. Turns out I had a burnt diode in my alternator diode pack. I swapped in an alternator from a junk yard and the problem went away. 
This happened after I jump started somebody else's car. I didn't reverse polarity or anything lame like that. I may have connected the negative directly to the battery and not to the block... or maybe my battery grounds were less than great.
If you are lucky enough to have a bosch alternator and no AC, you can change the diode pack with the alternator in the car. Just disconnect the battery first. Back when I did this last on my 87 Jetta, it was like a $30 part new, and you get fresh brushes in the deal. 


_Modified by pimpbot at 11:02 PM 11-5-2008_


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## alpinweiss (Aug 10, 2007)

*Re: ok when car running constant loss in battery volts (proudvwrabbitowner)*

I would also guess alternator problem. Many Rabbits of this era came with a Motorola alternator rather than the Bosch alternator (Bosch is the better of the two).
Yes, you can service the alternator while it is on the car, in some cases. However, I would recommend taking it off and completely replacing all wearing parts. This includes bearings, diodes, etc. You may also wish to replace the regulator and brushes. Or, you can simply buy a rebuilt alternator from a RELIABLE source.
Do some basic diagnosis first, to make sure you don't have another electrical drain on the system. Also make sure your battery is good.


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## Vdubsdrummer (Oct 9, 2008)

it sounds like you have a bad set of diodes in the alternator. take it out and bring to advanced to test it. an 80's alternator can't be more than $40 at advanced. easy fix. if the alternator fine than check the wiring going from the batter to the alternator to the start.


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## sared (Jan 14, 2009)

it can be related to the amperes that to the alternator or the system handles? it could be necessary to make a measurement of amperes besides the classic one of voltage?


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