We still have our original 12 volt accessory battery in our 2017 A3 Sportback e-tron. It appears to be working fine, though we are worried about whether it is time to replace it, even though we only have 20K miles on our e-tron. We do not wish to wake up one morning, go to our Audi, and discover that the 12V battery is dead, not allowing entry, starting, or anything else.
I have read estimates from Audi of $700 to replace the battery, which is way beyond the actual cost of the unit. I have been able to get to the battery itself and located 58-60 AH AGM batteries which work perfectly, costing in the $100-$170 range. The rest is all labor, plus updating the software for a replacement battery.
Has anyone replaced their A3 Sportback e-tron 12V battery? Did you have issues with Audi USA and the replacement? Did you choose elsewhere to have it installed?