Car dead - failed module somewhere? 2013 Allroad.

[Sepanger]

Hi all,

My battery seems to have been getting weaker of late, struggling to start the car. Fine, I'll replace it shortly. (5.5 years old)
This morning the car went dead soon after getting in. Several warning messages showed, including key fob not recognised, suggesting low voltage. I'm left with the warning symbols on in the bottom of the dash and no other electrical activity.
Connecting a battery charger to the posts or direct to the battery produces the same result, with the charger clicking in and out at less than 1A.
The central locking is dead but the lights remain on the dash after locking the door manually.

Any suggestions, please?
Thanks

Update: charger now flicking to max and back. Switched off for now.

[johnsimcox]

Like many modern cars the A6 has a sophisticated power management system which shuts down systems as power reduces. This can throw uup all sorts of stranges error messages and warning lights. I would suggest you either leave the battery on charge (probably disconnected from the vehicle for a day and try again or alternatively simply replace the battery with a new one and see if that restores the car to health

[Sepanger]

Thanks John.
I've disconnected the negative lead and the charger is still flicking on and off. Looks like I'll need a new battery. Fortunately I have family in the trade to help with that.

[AT.]

My answer is related to my former A6/C6, but probably helps, even I don't know any DIY solution.

I had to replace the battery, and I did it with a Bosch in a Bosch service. The symptoms were almost the same, the problem was, that they were not able to synchronise the battery with the MMI. After I replaced the battery in an Audi service, all the problem disappeared, and everything went fine. So, the solution is to teach the MMI the new battery and the "how to charge" sequence, and that's what you missed. I'm sorry, I don't know how to do it, but I know, that there is some "trick" to teach to MMI the new battery's charasteristics.

[Johnny31]

Last year, I started seeing strange problems on my car (13 reg) that I attributed to the install of the dash cam in parking mode (full time power supply).
To combat battery problems, I got the NOCO G7200 charger (comparable with Ctek I think) that is capable of handling almost any battery type and also compatible with charging over the "under the bonnet" terminals.
The thing can also supply enough power on its own to have the MMI going.
In any case, I did let the car charge over night twice since then (once initially and now if Feb, just before the trip to the mountains - as a precaution).
Haven't seen the low battery warning in my OBD11 app since the first time.
Worth mentioning that OBD11 can also set the battery type etc. for the new battery.

Hope this helps...

Sent from my mobile...

[Sepanger]

Thank you to all for your replies.

I installed a new battery and all seems well. (£198 trade for the battery + 30 mins for me to fit) We hooked up via the OBD and the only faults showing were low voltage and a mismatch on the software. (I did a non-official MMI/sat nav update recently) No resets appeared to be required aside from the time and the tripmeter.

I installed a Blackvue dashcam recently, with the voltage monitor unit, so I'll make sure that's functioning correctly.

A simple fix in the end.