Battery keeps going flat Audi S8 D2
11-09-2012, 03:59 AM
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Battery keeps going flat Audi S8 D2
Hi all i wonder if someone can help me.
I bought an S8 D2 1998 two months ago. When i first bought it i had to get a new battery. I live on an island in scotland and bought this car from a dealer on the mainland where i had the car transported so i could pick it up. When the car arrived it had a flat battery. I went to halfords and purchased a bosch battery for it. Its been fine since i changed it up until the last week where i drove it on the monday and left it a week. Upon going back to drive it, I tried to start it up but it just gave out a ticking noise!! So i jump started it took it for a spin left it started it again and all seemed fine. I had to go away again and have left the car for three days i went out to try and start it this morning and the battery is dead nothing!! I guess there is something draining the battery anybody got any ideas what it could be??? This is driving me mad!!! thanks in advance Anthony
I bought an S8 D2 1998 two months ago. When i first bought it i had to get a new battery. I live on an island in scotland and bought this car from a dealer on the mainland where i had the car transported so i could pick it up. When the car arrived it had a flat battery. I went to halfords and purchased a bosch battery for it. Its been fine since i changed it up until the last week where i drove it on the monday and left it a week. Upon going back to drive it, I tried to start it up but it just gave out a ticking noise!! So i jump started it took it for a spin left it started it again and all seemed fine. I had to go away again and have left the car for three days i went out to try and start it this morning and the battery is dead nothing!! I guess there is something draining the battery anybody got any ideas what it could be??? This is driving me mad!!! thanks in advance Anthony
11-09-2012, 04:10 PM
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Something seems to be draining the battery with the car turned off.
A new battery shouldn't behave that way, if it simply wasn't getting charged. A new battery should charge itself, with no drain on it.
I'm not very well versed in finding hidden electrical drains, but the right mechanic with a volt/ohm meter could trace it down. Or you may at least learn if there is indeed a car-off drain by disconnecting the battery after a long drive, then reconnect the next morning to see if it starts normally...if it's not dead then, you know it has a car-off drain.
P.S. I've never been to Lewis, but spent time on Skye some years back. Love your corner of the world...the weather doesn't bother me a bit...keeps away the riff-raff
A new battery shouldn't behave that way, if it simply wasn't getting charged. A new battery should charge itself, with no drain on it.
I'm not very well versed in finding hidden electrical drains, but the right mechanic with a volt/ohm meter could trace it down. Or you may at least learn if there is indeed a car-off drain by disconnecting the battery after a long drive, then reconnect the next morning to see if it starts normally...if it's not dead then, you know it has a car-off drain.
P.S. I've never been to Lewis, but spent time on Skye some years back. Love your corner of the world...the weather doesn't bother me a bit...keeps away the riff-raff
11-10-2012, 05:05 AM
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Something seems to be draining the battery with the car turned off.
A new battery shouldn't behave that way, if it simply wasn't getting charged. A new battery should charge itself, with no drain on it.
I'm not very well versed in finding hidden electrical drains, but the right mechanic with a volt/ohm meter could trace it down. Or you may at least learn if there is indeed a car-off drain by disconnecting the battery after a long drive, then reconnect the next morning to see if it starts normally...if it's not dead then, you know it has a car-off drain.
P.S. I've never been to Lewis, but spent time on Skye some years back. Love your corner of the world...the weather doesn't bother me a bit...keeps away the riff-raff
A new battery shouldn't behave that way, if it simply wasn't getting charged. A new battery should charge itself, with no drain on it.
I'm not very well versed in finding hidden electrical drains, but the right mechanic with a volt/ohm meter could trace it down. Or you may at least learn if there is indeed a car-off drain by disconnecting the battery after a long drive, then reconnect the next morning to see if it starts normally...if it's not dead then, you know it has a car-off drain.
P.S. I've never been to Lewis, but spent time on Skye some years back. Love your corner of the world...the weather doesn't bother me a bit...keeps away the riff-raff
I've booked into my local garage next week so he can do a few checks on it, hopefully it's not going to be something expensive and will be an easy fix!!!!
I think I'll give your idea a try too. Jumped it again yesterday and its dead again today.
If you like Skye you'd love Lewis great place!!! Weather doesn't really bother me either, plus we had a great summer this year which always makes things better!!!
04-17-2015, 11:36 PM
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I've been doing a final check after rebuilding the alternator, and nowhere can I find the figure for normal battery current drain with car at rest.
My 2001 S8 shows 180mA. I found that by removing the fuse for the phone, which will never again be used, the drain reduced to 70mA, which seems more acceptable.
The guy in the video said modern cars can run up to 35mA. Ours may run a bit higher by the look of it. The difference isn't enough to run a bulb, never the less, I had all the ancillary lighting and more fuses pulled.
The phone fuse is 5A and in the boot fuse box above the battery.
(The video shows him measuring voltage drop across a resistance, which by conversion shows current. Equally a meter can be used to directly measure current, in amps.)
My 2001 S8 shows 180mA. I found that by removing the fuse for the phone, which will never again be used, the drain reduced to 70mA, which seems more acceptable.
The guy in the video said modern cars can run up to 35mA. Ours may run a bit higher by the look of it. The difference isn't enough to run a bulb, never the less, I had all the ancillary lighting and more fuses pulled.
The phone fuse is 5A and in the boot fuse box above the battery.
(The video shows him measuring voltage drop across a resistance, which by conversion shows current. Equally a meter can be used to directly measure current, in amps.)
Last edited by HerrCutt; 04-17-2015 at 11:54 PM.
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04-19-2015, 08:09 PM
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I like Herrcutt's suggestion about the car phone - I might look into that myself (nice first post by the way!).
I'm also in agreement after watching that video that there is no need to build a resister circuit to run in series if you own a multimeter, simply use the multimeter in the Amps setting. Disconnect the negative terminal (as per video) and reform the circuit with the multimeter probes. Just be sure they are plugged into the multimeter correctly as the positive probe often has a different plug for Volts and Amps readings. Then simply set the multimeter to the Amps reading and observe.
A D2 doesn't require much time to fully shut down - minutes only. Just be aware that disconnecting and reconnecting the battery may wake up a module or two, so give them a couple of minutes to go back to standby. And don't run any heavy loads through the multimeter when being used to connect the negative terminal to the battery as the multimeter is only designed to small to moderate loads (ie don't try and start the thing!).
Search 'car parasitic power drain' on youtube and there are plenty of videos to watch.
My car currently has the exact same symptoms as the OP. I've been a bit lazy in not investigating it further, but it only becomes an issue if I'm not using the car for a couple of days.
I have a 210mA constant drain which will run the battery from charged to flat in around 4 days. Although it's technically a 100Ah battery, I doubt I get to more than about 75% capacity from a 4A smart charger.
I have tested the navigation and entertainment systems initially, as I was blaming the TV and CD changer (which doesn't work currently) for the drain, they have tested fine however. I'm thinking I may have tested the phone circuit as I think I did the rear fuse panel - oh well...
Another suggested area to look, should all fuses/circuits check out, is the alternator. It seems that the voltage regulator can cause a drain when failing - we shall see!
Although not stated for the S8 specifically, the banter around the internet for modern cars is that they should use less than 50mA when shut down. Less than 10mA would be ideal.
I simply run a screwdriver through the boot lock to 'close' it. light will go out instantly and the car will think the boot is closed. You can even lock the car with the remote (with the boot open) to assist with your trouble shooting!
I'm also in agreement after watching that video that there is no need to build a resister circuit to run in series if you own a multimeter, simply use the multimeter in the Amps setting. Disconnect the negative terminal (as per video) and reform the circuit with the multimeter probes. Just be sure they are plugged into the multimeter correctly as the positive probe often has a different plug for Volts and Amps readings. Then simply set the multimeter to the Amps reading and observe.
A D2 doesn't require much time to fully shut down - minutes only. Just be aware that disconnecting and reconnecting the battery may wake up a module or two, so give them a couple of minutes to go back to standby. And don't run any heavy loads through the multimeter when being used to connect the negative terminal to the battery as the multimeter is only designed to small to moderate loads (ie don't try and start the thing!).
Search 'car parasitic power drain' on youtube and there are plenty of videos to watch.
My car currently has the exact same symptoms as the OP. I've been a bit lazy in not investigating it further, but it only becomes an issue if I'm not using the car for a couple of days.
I have a 210mA constant drain which will run the battery from charged to flat in around 4 days. Although it's technically a 100Ah battery, I doubt I get to more than about 75% capacity from a 4A smart charger.
I have tested the navigation and entertainment systems initially, as I was blaming the TV and CD changer (which doesn't work currently) for the drain, they have tested fine however. I'm thinking I may have tested the phone circuit as I think I did the rear fuse panel - oh well...
Another suggested area to look, should all fuses/circuits check out, is the alternator. It seems that the voltage regulator can cause a drain when failing - we shall see!
Although not stated for the S8 specifically, the banter around the internet for modern cars is that they should use less than 50mA when shut down. Less than 10mA would be ideal.
I simply run a screwdriver through the boot lock to 'close' it. light will go out instantly and the car will think the boot is closed. You can even lock the car with the remote (with the boot open) to assist with your trouble shooting!