Charred/Burnt Battery Fuse Box...?
 

*** I know this is the Jetta Section, but my problem relates more to the charging system on the 2.0L 8V engine that is found in most MK4's than the model of car ***

The charging system in my mothers 2004 New Beetle Cabriolet started acting up last week (dash lights going crazy, engine chugging). I ran a few tests with my voltage meter and everything pointed to the alternator. A buddy of mine who has an alternator rebuild shop tested it and the output was all over the place. So he was able to get me either the 90amp which it already had or the higher output one at 120amp for $20 bucks more and he claims it should work without any upgrades to the cars wiring. I bought the 120amp alternator and installed this evening. I hooked my multimeter to the battery and it had a charge of 12.65 volts...good to go:). I started the car and the voltage immediately dropped to 12.14v:mad:...charging system still not working. I tested the voltage between the ground post on the battery and positive connector at the alternator and it was fluctuating between 12.80 and 13.90volts at idle so the part is working and its a wiring/connection issue. I decided to start back and the battery and check all of my connectors again and I realized I forgot about the fuse box ontop of the battery box. I open it up and the thick black alternator wire and the surrounding fuse is a mixture of melted charred black plastic...WTF?:eek:

Has this happened to anyone before? Did the old alternator cause this on its way out or could this be me adding the higher 120amp alternator instead of the 90amp one? I read on some other forums that it could also be the positive wire from the alternator and that it isn't of great quality?

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Just because you fitted a 120amp alternator doesn't mean that 120amps will be going through that system all the time. The output current will vary depending on electrical load.

The fuse and connection could have been deteriorating over the years, just make sure they are clean and secure.

Thanks. I think I'm going to change the wire. Should I use a heavy duty 2 gauge wire?

Thanks

Burnt Leads un VW VAG group
 

Hello ! Thanks to welcome me
I understand that this thread in old... But this incident is a shameful thing well documented . Swept under the carpet as an omerta in the brand dealers
I followed many cases in Europe and else
Furthermore the poor customers had their alternator accused, and costly $$ replaced !! as the ""solution"" wether the cause is a catastropic quality of the métal terminals of the burnt wires
And the crass ignorance that a fuse supposed to melt at 90 ou 110 Amp stays to be................. a resistor during in its range of use. https://forum-auto.caradisiac.com/to...ffinit%C3%A9s/
Jacques Paris France
Thanks



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