Alternator output specs
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1st Gear
Joined: Nov 2008
Posts: 5
Alternator output specs
Hi all,
I have been chasing a random electrical problem on my B5 S4 for the past 6 months.
Finally got a VAG-COM and connected it up to find that the 'battery voltage' would drop as low as 12.8 while the car is running.
It has so far killed a battery, and caused the ECU to 'lose some code' and had to be reflashed.
I was wondering (because I cant find in the service manual) what the rated output of the alternator should be...in my experience, 13.7-14.1v is standard output for most alternators. For the duration of the logging I did today, it did not go above 13.4 volts - too low in my opinion.
Cheers,
Andrew
I have been chasing a random electrical problem on my B5 S4 for the past 6 months.
Finally got a VAG-COM and connected it up to find that the 'battery voltage' would drop as low as 12.8 while the car is running.
It has so far killed a battery, and caused the ECU to 'lose some code' and had to be reflashed.
I was wondering (because I cant find in the service manual) what the rated output of the alternator should be...in my experience, 13.7-14.1v is standard output for most alternators. For the duration of the logging I did today, it did not go above 13.4 volts - too low in my opinion.
Cheers,
Andrew
1st Gear
Joined: Jan 2011
Posts: 66
From: New England
Concur, with the engine running and applying a voltmeter across the battery terminals you should be reading ~14VDC. Any lower is suspect - degraded alternator windings/bushes, loose belt, loose connections, degraded wiring, etc.
Hi all,
I have been chasing a random electrical problem on my B5 S4 for the past 6 months.
Finally got a VAG-COM and connected it up to find that the 'battery voltage' would drop as low as 12.8 while the car is running.
It has so far killed a battery, and caused the ECU to 'lose some code' and had to be reflashed.
I was wondering (because I cant find in the service manual) what the rated output of the alternator should be...in my experience, 13.7-14.1v is standard output for most alternators. For the duration of the logging I did today, it did not go above 13.4 volts - too low in my opinion.
Cheers,
Andrew
I have been chasing a random electrical problem on my B5 S4 for the past 6 months.
Finally got a VAG-COM and connected it up to find that the 'battery voltage' would drop as low as 12.8 while the car is running.
It has so far killed a battery, and caused the ECU to 'lose some code' and had to be reflashed.
I was wondering (because I cant find in the service manual) what the rated output of the alternator should be...in my experience, 13.7-14.1v is standard output for most alternators. For the duration of the logging I did today, it did not go above 13.4 volts - too low in my opinion.
Cheers,
Andrew
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