Doors are draining down the battery

Hi,

By any chance, do you know the codes that were found when it was checked? As far as a battery draw, if it is showing 100% and then drops to 10%, is that when the vehicle is running or not?

I don't know if this will help, but here is a link that explains how to identify a battery draw (parasitic electrical draw). You may want to try it to determine if there is something with the door handles.

https://www.2carpros.com/articles/car-battery-dead-overnight

I've worked on several A8 vehicles and they are extremely over-engineered and difficult to diagnose at times, so let me know exactly what is happening as far as the drain, what as far as the door handles did they mention, and anything you can think of. Heck, the alternator on this vehicle is liquid-cooled by the engine cooling system, so I need as much as possible. LOL

Take care,

Joe

Hi there,


Thanks for the ideas in the video. I tried all the simple one, but to no avail. The more complicated ones I don't have the competence or confidence to tackle.

I gave all the information from the invoice to the previous owner by the mechanic in my original question. The only thing i can add is that the battery keeps at 100% for a day or two, and then plummets to 10% in a matter of an hour or less. I think that a lot depends on the number of times I open the doors or the trunk.

The battery is 2 years old, and I had it checked and was told it was fine.

I was thinking of several options, but don't know if they'll have other side effects. Can you give me some feedback on these ideas, please.

1. Remove the fuse for the central locking, and only use the key to get in. Unfortunately I can't seem to find which fuse that is from the owner's manual.

2. Remove the door closing fuse that pulls the door closed (and the trunk). I think that I have found them described as (comfort system).

3. Temporarily disconnect the battery each time i stop for the night. I'm currently on a several month camping and hiking trip around the western US, and will be leaving the car sometimes for several days. If I disconnect the battery, will it be enough only to disconnect the positive terminal (the negative terminal is very difficult to get to).

4. I am planning to buy a jumper battery to keep in the car in case the battery runs completely flat.

Sorry to have taken so long to reply but i can only do email where i can find wifi access, and being up in the mountains of Montana there aren't many such places.

Thanks very much.

Jeff Woods (aged 74).

Jeff,


God Bless you!!! I'm 56 and don't think I could make it with you. LOL

If you remove the fuse for the central locking system, you will lose a few different things, so that wouldn't be a good idea. The door closing is the same. There are multiple modules involved.

As far as disconnecting the battery, that would be your best choice. The only thing that you need to remember is this. When power is lost to the modules, you may experience some relearn symptoms from the PCM. Things will return to normal. It may take a couple of miles.

Also, if it is possible, I always recommend removing the negative battery terminal. If it is still attached and you bump something while removing the positive cable, things could be damaged.

If you chose to do it this way, just really be careful not to short the tool out between the positive and a ground on the vehicle.

And certainly, a jumper pack is a good idea.

Take care, be careful, and enjoy yourself.

Take care,

Joe

Thanks very much for your advice. I really do appreciate it.

Sincerely,

Jeff Woods

Hey Joe,

Thanks for the information. I had already looked at that link.

The battery drops when the car is stationary. When the engine is running the battery level charges up from 10% to 100% in about 45 minutes.

I looked at the invoice given to the previous owner. It says:

Found draw coming from all 4 door handles
Faults stored for implausible signal - found switch
Does not change when buttons depressed
Changed settings for now that keyless entry/start will not operate and shuts down the draw - will need to use remote for lock/unlock.

No codes are mentioned.

As a point of interest, how long should it take to find the problem and resolve it at an electrician's? Would there be any need for new parts or is it only a labor time question?

Thanks.

Jeff Woods

Hi Jeff,

I have to be honest, chances are something has failed and a part will be needed. However, a short in a wire can do this as well.

Labor is somewhat hard to determine simply because it can take 20 minutes or 10 hours to find it. A dealership will charge a ton. If you can find an automotive electric repair shop, that is your best bet. Hopefully, they will have seen this problem before.

You have to remember, anything with an A8 is never cheap. They are extremely overengineered and when things fail, it can become a nightmare. I owned one for several years, the same year as yours, and to say the least, it was one of the nicest vehicles I ever owned. However, when I had a 3" plastic coolant hose that went to the oil cooler fail, step one in the manual was to remove the engine. Ugh!!! I did it without, but it wasn't fun.

Let me know if I can help you in any way.

Take care,
Joe

Hey Joe,

Thanks for your comments. I only paid $2,000.00 for it last year (knowing that it had this electrical problem). The car came with a solar battery charger that plugs into the cigarette lighter, and feeds into the battery. I'm currently testing it to see if it can counter the draw.

If i can't resolve it, then I'll have to bite the bullet and get an electrician to fix it. I have bought a jump battery in case I end up with a flat battery, as I'm often out in the boonies on my 6 month camping and hiking trip around the western US. And i have jumper cables and a mains electricity battery charger.

You are very welcome. If there is anything I can do to help, let me know. Enjoy the trip. If you have a jumper pack, just keep it charged. LOL

Take care of yourself. If you have a chance, let me know what happens or if you determine the draw.

Joe

Okay, I'll keep you informed.

Jeff

Hey Joe,

I've done a few experiments.

First I switched off the central locking (through the MMI system).

Then I opened all the windows so I didn't have to open any doors to get anything out of the car.

Finally I plugged in a solar battery charger into the cigarette lighter. The particular location has given me more than 12 hours a day for 3 days.

I checked the battery level several times a day, and each time it remained at 100%.

Now I'll stop one or another of these three and watch the impact on the battery level.

I don't know if you'll find this information useful in other people's queries.

Jeff

Jeff,

Thank you for the update, and yes I feel confident it will help others.

Stay in touch and let me know if there is anything I can do to help.

Take care,

Joe

Hey Joe,

Okay. Ta

Jeff