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I'm putting very few miles on my RS4, so time intervals between rides can be several weeks. This of course poses the risk of deep discharging the battery. Also, the car is stored at a location without access to electricity, preventing me to hook up a trickle charger.

Now, on my classic cars, which present the same issue, I have installed battery disconnect switches to alleviate that situation. Disconnected batteries can go for months w/o any problems.

So, I'm thinking about installing one on the Audi, too.

But: I don't have a clear picture on what disconnecting the battery from the car's electronics (for weeks) will do to such a much more modern car. I'm thinking along the lines of losing 'learned parameters' in the ECU e.g., or codings in other controllers...

What am I missing? Or would that switch actually be benign?

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I dont think disconnecting the battery will do any harm.
Are you concerned about security at all? as any alarm etc will be disabled and you'd be best leaving the doors/boot unlocked.

The only things that spring to mind are:
keys will likely need resyncing which is a 2 minute job
windows might need recalibrating so the one press up/down works
the RNS-E may need to have the code put in so make sure you have this available

HTH
Mike

You will have to do the thing with the key fob for the operation for the windows on the fob if you use it. Think you will have to calibrate the fob as mentioned witch is easy enough to do ignition on and press the unlock or lock on the fob and it done.

Thx @all for the input.

mikep99 wrote: ↑

Fri May 17, 2019 10:22 am

Are you concerned about security at all?

Good point... I just realized that I have a conceptual problem. In other cars, i can FIRST lock the whole car using central locking, and THEN disconnect/remove the battery, because they are located in the engine bay... With the battery in the boot, things are more complicated. I would have to move the battery disconnect switch to a location accessible from the outside of the car. Problems, problems, ...

And having to reprogram/relearn stuff doesn't make this project any more attractive either...

Suppose you you could use one of these - https://www.ebay.co.uk/itm/Discarnect-C ... 1438.l2649
You could extend the fused wire that just provides enough current for the electrics.
You could lock / unlock the car with this connected.
The extension could come out of the boot with a switch on perhaps.

Mike

That could be good solution if the wires were extended outside you could undo the brass connector, lock the car, disconnect the fuse and all of the electrics and then when you come back re-insert the fuse providing enough power to unlock the car.

Can you not lock the car then use the boot open button on the key? Then disconnect battery and shut the boot? Then use key in lock to open boot

James1984 wrote: ↑

Mon May 20, 2019 4:32 pm

Can you not lock the car then use the boot open button on the key? Then disconnect battery and shut the boot? Then use key in lock to open boot

I thought you could lock the doors using the key and shut the boot with the battery disconnected and then use the key to open the boot directly or unlock the doors.

MikeFish wrote: ↑

Mon May 20, 2019 7:22 pm

James1984 wrote: ↑

Mon May 20, 2019 4:32 pm

Can you not lock the car then use the boot open button on the key? Then disconnect battery and shut the boot? Then use key in lock to open boot

I thought you could lock the doors using the key and shut the boot with the battery disconnected and then use the key to open the boot directly or unlock the doors.

Ah, you could be right.

Us Avant owners (well me at least) dont have the luxury of being able to use the key in the boot

Not sure whether the OPs got a saloon or avant...

Mike

Yes, good point, I didn't think about the avant.

Wow, this discussion's going somewhere... Thanks for that.

mikep99 wrote: ↑

Mon May 20, 2019 7:33 pm

Us Avant owners (well me at least) dont have the luxury of being able to use the key in the boot

Not sure whether the OPs got a saloon or avant...

Yes, the OP has an Avant, which poses procedural problems mentioned by me and others.

But, the picture from above gave me ideas, and I had already figured out a plan on how to implement a solution, both in terms of procedure and technical implementation. Only to abandon it shortly thereafter...

What I think I'm going to do is install a simple battery disconect switch - and nothing else. And in order to circumvent the procedural problem (accessing the battery in the boot while the car is already locked), I'll buy a small booster battery pack, which connects to the jump lead terminals in the engine bay, which will power the car's electronics during the short period where the main battery is already disconnected, and we still need power to lock the car.

Brilliat concept, if I may say so, plus a perfectly valid reason to buy new tools. A win-win situation if there ever was one.

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