View Full Version : Persistent Battery Drain - Any fresh ideas ?
vrlife
March 16th, 2019, 18:41
RS6 with a persistent 2.9A drain, measured with an ammeter on the battery.
Spec is it should be less than 0.5A
When locking car it's still there, it will run flat overnight unless kept on charger
Pulled all the fuses in the side panel - no difference
Pulled all the relays under the drivers kick panel - no difference
Pulled the ECU (as much as can with half the connector effectively welded on) - no difference
Gave it to experienced Audi Dealer with veteran tech - no clue.
Anything am missing ?
hahnmgh63
March 16th, 2019, 22:07
You've pretty much done what any good troubleshooter would do. Any aftermarket accessories? Alternator going bad? Try disconnecting the power leads under the windshield cowl on the passenger side one at a time and see which one drops the current, then reverse trace that big lead.
vrlife
March 17th, 2019, 20:13
Which big wires are you speaking of ?
Only saw one from the Battery (hard line from the trunk) in there.
It's splits into alternator and the rest - are you saying separate those two from the battery line ?
Welcome suggestions for any other major hard line taps to try ?
Alternator is good, tested and works well.
Have a flashed ECU, perhaps that's not properly putting car into sleep mode ?
Or perhaps the comfort/locking module ?
hahnmgh63
March 17th, 2019, 23:32
Yea, that's what I'm thinking. Separate the lines and check the resistance and see which one has the least to ground.
canyon
March 18th, 2019, 03:12
Make sure your hood switch is reading closed when the hood is closed. Number 1 problem I see with the C5's having a battery draw.
vrlife
March 24th, 2019, 22:51
Make sure your hood switch is reading closed when the hood is closed. Number 1 problem I see with the C5's having a battery draw.
Hang-on, if hood switch wasn't closing properly then the car wouldn't beep when all locked from the remote.
Correct ?
Mine beeps just fine - so central locking must be reading everything closed including the hood.
lswing
March 25th, 2019, 18:35
I thought you could lock and arm without closing the hood all the way? You on original battery still? Could it be the battery simply isn't holding a charge and draining? Any work or anything new done?