Charred/Burnt Battery Fuse Box...?
#1
01-11-2013 | 01:40 AM
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Joined: Dec 2012
Posts: 6
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
...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?
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?
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...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?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?
Last edited by mr_mk4; 01-11-2013 at 02:02 AM.
#2
01-11-2013 | 07:16 AM
Super Moderator
Joined: Sep 2009
Posts: 2,648
From: Stoke on Trent, England
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.
The fuse and connection could have been deteriorating over the years, just make sure they are clean and secure.
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