Weird Issue -- Won't Start Well
09-15-2008, 06:54 AM
#1
AudiWorld Member
Thread Starter
Weird Issue -- Won't Start Well
This concerns my 2000 A6 4.2. Order of events...
* Battery dies after being in car 3 years. I jump start it. Local mechanic reports battery is marginal, suggests driving car for an hour to charge. Done. Car restarts fine several times after stops of 30-60 minutes.
* Next morning, battery is dead again. I jump the battery again. Local mechanic puts in new battery. Car drives fine for 3 days, then battery is dead again one morning. I jump start it to get it going and run it for an hour. Again, car restarts fine several times after short stops.
* Mechanic had suggested possible parasitic energy drain, so I hook up multimeter and start experimenting with fuses. I discover that when fuses 14, 15, 37, and 38 are removed, the car draws zero amps. 14 is interior lights, alarm, mirrors, seat memory. 15 is instrument cluster, etc. 37 is radio. 38 is central locking. Of all those, 38 seems to draw the most juice. I pull the 4 fuses and let car sit overnight.
* Next morning, voltmeter shows about 9 volts after key is turned to run position but not started. If I turn the key to start position, the engine cranks VERY slowly and finally turns over about about 5 seconds.
* VAG COM repots nothing out of the ordinary, aside from some "Supply Voltage Too Low - Intermittent" errors
Any guesses as to what in the world is going on?
* Battery dies after being in car 3 years. I jump start it. Local mechanic reports battery is marginal, suggests driving car for an hour to charge. Done. Car restarts fine several times after stops of 30-60 minutes.
* Next morning, battery is dead again. I jump the battery again. Local mechanic puts in new battery. Car drives fine for 3 days, then battery is dead again one morning. I jump start it to get it going and run it for an hour. Again, car restarts fine several times after short stops.
* Mechanic had suggested possible parasitic energy drain, so I hook up multimeter and start experimenting with fuses. I discover that when fuses 14, 15, 37, and 38 are removed, the car draws zero amps. 14 is interior lights, alarm, mirrors, seat memory. 15 is instrument cluster, etc. 37 is radio. 38 is central locking. Of all those, 38 seems to draw the most juice. I pull the 4 fuses and let car sit overnight.
* Next morning, voltmeter shows about 9 volts after key is turned to run position but not started. If I turn the key to start position, the engine cranks VERY slowly and finally turns over about about 5 seconds.
* VAG COM repots nothing out of the ordinary, aside from some "Supply Voltage Too Low - Intermittent" errors
Any guesses as to what in the world is going on?
09-15-2008, 07:21 AM
#5
Not alternator. Sounds like the new battery is junk. Try this:
Drive car during the day.
Park car.
Turn key on and check battery voltage.
Disconnect negative battery terminal and leave car overnight.
Reconnect battery in the morning and recheck voltage.
If voltage has dropped significantly overnight or the car won't start in the morning, replace battery.
Park car.
Turn key on and check battery voltage.
Disconnect negative battery terminal and leave car overnight.
Reconnect battery in the morning and recheck voltage.
If voltage has dropped significantly overnight or the car won't start in the morning, replace battery.
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09-15-2008, 08:13 AM
#9
AudiWorld Member
Thread Starter
Re: There are so many electrical systems in the car that require constant power that...
True, however, when I pulled the four fuses I mentioned and got a zero amp load (with my multimeter connected between the battery and the negative cable) I was pretty sure I'd shut everything down. But you are correct about pulling the battery cable -- I'll give that a shot.