I have done tons of research but I am still not finding the source of my problem. My 2007 GTC has two new batteries and they both show over 13VDC and indicate on the tender that they are fully charged......Yet, my car appears to be dead as the doors will not unlock, the trunk will not open, the clock has reset to 12:00 PM. When I try to start it by turning the key clockwise, I get a roof fault and sometimes a leveling fault. If I turn it counter clockwise, it will start and it will show a low battery. The main battery is not low.

In addition, I occasionally get an alarm that I cannot seem to turn off. Now, suddenly, I just started it and ran it around the block and of course everything disappeared . This is normal and has been doing this for the past two days. What is different, is this time the car, after being shut off is not dead! Everything acts like normal!

Any thoughts? BTW the car only has 10,000 miles so it is not abused. The batteries are less than two weeks old and all connections are tight and secure.

 

1. Did you fit the new batteries yourself and did you use the correct replacement procedure ?
2. Is it sat on the charger at all times while not in use, or is this something youve recently started doing ?
3. Does it just need a good long drive and to be driven a lot more ?

 

No, I did not do them myself. The AUDI dealer did it with new Audi batteries. They have been on a tender the whole time that I have owned the car. Everything seemed to work fine until two days ago. I took it for a 30 mile drive twice yesterday and still had the same results. I tied disconnecting the house battery and charging it with the exact same result. Although, when I first hooked it up, everything seemed to work.

 

So, it was fine for a few weeks after the batteries where replaced, albeit you dont know for sure if the correct procedure was adopted.

When you say that " you tried disconnecting the house battery " .... what do you mean by "tried" ?

 

Recheck the battery terminals, could one of them slipped back up when tightened, I usually give them a light tap to make sure they are on before tightening

 

I disconnected the negative terminal on the main battery (not the start battery) and then charged the battery until it was full but it only took a few minutes @ 2 AMPs as it was already full. I put the negative terminal back on and tried it and now it seems to be working alright. I know for sure in another couple of hours.

 

Thanks to all of you. It would appear that you are correct that the negative terminal was not tight enough. Once I put it back on and tightened it with a socket and a ratchet, rather than an open ended wrench, all returned to normal. When the Audi dealer changed the battery and installed it they apparently did not tighten it down enough and when I checked it I used an open end wrench and that seemed tight. Thanks again!

 

You're welcome, great result

 

Back to square one again! Tonight, with the battery tender connected and showing a full charge, the car thinks that it has a dead battery. While the battery is new, is it possible that the 13 plus volts is a "surface charge and yet it has no amps? Why else would the car think that the battery is dead? Nothing works but yet if I do start the car, by using both batteries (counter clockwise first) the car will start and then everything will work for 5 minutes after I shut down the engine. Then everything is dead again.

Thanks

 

Have you contacted the Audi dealership yet to verify they replaced them adopting the correct procedure ?

 

I actually have now found the problem and now I need help. It turns out that the negative battery cable, where it attaches to the car, in the trunk, is lose. If I move it power restores to the car and everything works. Now the question. How can I tighten that cable? It looks like there is a covering over what might be a nut but I am not sure. Do I have to remove the battery to get to it? Would an open end wrench work or a crow foot wrench with the battery in place? Does the covering come off to expose the nut?

Thanks so much!

 

Isn't it great when you find the route cause. I cant help with the tightening sorry, mines different being the convertible.

 

Mine is also a convertible. GTC. The cable is next to the tail light but just underneath a piece of metal. It is night time here but it appears to have some sort of cover over it that covers the nut. Tomorrow, I'll be able to explore more but I afraid to do too much tonight as I do not wish to set off the alarm and scare all of my neighbors.

 

Hello @scotstern ,
There should be nothing over the nut, what you are looking at is a domed nut, therefore you would use a socket to tighten it, 11 or 12 mm iirc.

It should look like #2 in the layout attached, #2 is a welded stud with the domed cap nut.

Johnny

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Johnny, thank you so much. All of you helped me to solve a very perplexing problem. It took a 13mm socket to tighten it and I will say that the attachment process seems a bit Mickey Mouse to me as I would rather have a bolt instead of an acorn nut but if it works, it's OK with me. You all were very helpful and I am really appreciative.