astrorat

Hello,

I am at a loss as to what is wrong. This morning I went to my wife's A8L and it appears that the rear cabin lights were left on all night. Put in the key and turn to start the engine and nothing. No lights to the center console.

I tried using a "brick" style battery charger that plugs into the cigarette lighter and followed the instructions (leave plugged in for 45 minutes). Turned the key and still nothing.

I tried to jump start the car and still nothing. I left the "donor" car running for about 15 minutes or so. Still nothing.

I bought a new battery and a volt-meter to test the old battery.

Before I installed the new battery, I checked both batteries with the volt meter and both were around 12.5 volts. Weird. The "old" battery registered 12.5 volts but the car would not start.

I checked fuses in all three fuse boxes (at least the ones that seemed to make sense to be a possible cause to the problem and all fuses were good.

The connections to the "old" battery are solid and there is no corrosion around the terminal. The battery is probably 5 years old or so, but has not given my wife any issues until today.

Any thoughts on what might be going on with the car? I just can't think of what it might be. Thanks much.

Lane

Jack88

Bad batteries can read normal voltages until you place them under load. Did you regain any of the interior lights with the effort to charge it? Did you follow the jumping instructions carefully? Improper jumping of this car can damage it, you aren't supposed to try to start it with anything still hooked up to the battery, nor are you supposed to use any quick charge methods. I don't know if the cigarette lighter style chargers would work in an A8. You may have blown the big fuse trying to jump start it, it's connected to the positive terminal in a black box, if I recall it's a 60 amp fuse.

astrorat

Thanks. I will check the 60 amp fuse.

When jump starting, I connected the terminals in the correct order and used the negative "post" above the battery and not the negative battery terminal. I did try to start the Audi while the battery was still connected to the battering of the "donor" car while it was running (also I got no response when I turned the key).

astrorat

I am trying to locate the big fuse, but I am having difficulty (I have not worked near the battery on this car before). There is a black box that sits on the front (towards the trunk space) that is on the left side of the battery (sort of in front of the negative terminal). One of the leads from the positive terminal goes into this box. I opened the box and there seems to be a "connector" behind a black covering with a "clip" on both ends that appear to hold it in place. I tried to gently push the clips aside and remove this black cover, but could not grip it enough. I did not want to force it, just in case it was not supposed to be removed without a tool, etc.

Can you tell me about where I can find the big fuse? Thanks, again.

astrorat

One more thing ...

If I insert the key and try to turn the headlights on, the dash lights come on and the door buzzer will sound, but the headlights will ignite.

Shark_V8

interior lights cannot be left on as they shutdown, certainly when load shedding kicks in,

i doubt its the battery with 12.5 and since it was good the day before,

richard-tx

I have seen batteries be good in the morning, and by afternoon they were bad. All it takes is a bit of plate material to flake off and short out a single plate. I have had that happen to two die hard batteries. I will never buy another battery from Sears.

MP4.2+6.0

The box you mention is the current auto disconnect box if car is in accident. It is a small explosive charge device. Don't fool with that, and if lights and such are working, power is flowing past there. The 60A fuse is part of the fuse panel above the battery. But it is not one of the pull out type color coded plastic fuses like many probably think. It is a "fusible link," meaning a piece of barbell shaped bare metal bolted between two terminals with some small nuts. I think it is under a small cover. Look in that area and you should spot it/them.

FWIW though, 60A fuse has more to do with things like MMI not working. I'm not familiar with it relating to starting car. For OP, you are starting it with a key in the ignition, correct? (as in, not push button start). With a fresh battery it really should turn over unless something else is wrong. For charging, cigarette lighter type charger sounds pretty amemic. Big car, big draws, big battery = better charger.

And yes, one drain down on an older battery and that can be it in pretty short order.

astrorat

Yes, it is a key start and not a push start.

There is power to light the dash and the cabin lights work as well, but when the key is turned, nothing happens.

astrorat

Well, I am not sure what to say. When I went to the car in the morning, the interior lights above the rear seat were on. Normally the lights go off, but for whatever reason, the lights above the rear seat remained on all night.

Thanks to everyone for all the comments. You are all very helpful.