I'm having trouble with my S8 (4.2) battery discharging in a day or so. I meaured the drain current and traced it to the radio fuse in the boot. The current drawn was 2.8 Amps!. With the radio fuse out all seems OK. Today I was going to try and trace the source but now, if I put the fuse in, The current goes to 2.1 amps for 10 seconds or so, then drops to 0.15A. I switch on the radio, the curren t goes to 2.1A. Swith off again and then drops to 0.28A and stays there. I even locked the car and checked the current for a while, but it now stays at 0.28A. The 2.8A drain seems to be gone. I did take the connector out of the amplifier thinking it might not be getting the "switch off" signal from the head unit, and now all seems OK. Only - is 0.28A constant drain acceptable from the radio when it's off? That seems to be the only drain there is. That equates to 6.72Ah per day. On a 100Ah battery that will only give about 14 days - but then the battery is completely dead and wont start the car. Any idee what the acceptable drain would be?
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1993 URS4 530hp Twincharged
2002 S8 -
Maybe the radio ist somewhat blown, even the only symptom is the power consumption.
I would compare that 0.28A with an other radio just connected to the battery..?
'93 Audi S2 Avant panthero black, 412.000km
'94 Audi S4 C4 Avant 303Tkm, KW, Brembos, BN-Pipes, Bose, S6 front (sold)
'93 Audi S4 C4 Avant, 260Tkm
'88 Audi 100 Avant turbo 44Q
'84 Audi 80 quattro tornado red
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The average battery capacity for our batteries is 70 amp hour.
Assume you need 50% capacity left to start the car and allowing for the capacity of the battery decreasing with age as it does, that leaves you with 35 amp hour of capacity to drain away.
Assume you want the car to start after 2 weeks, 14 days, thats 336 hours and gives you a leakage current of 0.1 amp (100mA).
In reality depending on how leaky your alternator, radio and alarm are in the off condition I'd expect the typical battery drain current to be 10 to 20 mA.
JohnComment
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I know a Polo 6N that starts after a lot more than 2 weeks without problems. With my S2 I could not try this out yet.
'93 Audi S2 Avant panthero black, 412.000km
'94 Audi S4 C4 Avant 303Tkm, KW, Brembos, BN-Pipes, Bose, S6 front (sold)
'93 Audi S4 C4 Avant, 260Tkm
'88 Audi 100 Avant turbo 44Q
'84 Audi 80 quattro tornado red
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Thanx Guys. I removed the radio - and even though it was off all day the casing really hot. Withg the head unit disconnected the power falls to about 10mA, so it seems the head ubit is the culprit. Now where do I send it to have it repaired? I'm in South Africa and I don't really want to go to the local Audi dealers.1993 URS4 530hp Twincharged
2002 S8Comment
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IIRC the Head units are made by Blaupunkt. I would try the local dealer in for Blaupunkt in your country...
HTH
Cheers,
SteveThe Perfectionist
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Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.
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