RS6 Auxiliary Battery Issues Causing Multiple Failures

I had a very similar battery malfunction with my 2020 RS7. Started with unusual electrical glitches and engine start problems, which turned out to be related to low voltage issues. Having some experience with electrical car problems, I first thought it was the main battery, but the workshop diagnosed a failing auxiliary battery causing a voltage drop across multiple systems. The repair process was straightforward, they ran a complete diagnostic scan, confirmed the auxiliary battery was degraded, and replaced it. Total cost was 290 Euro including parts and labor. Since the replacement, all electrical issues disappeared and the car starts perfectly. Worth noting that auxiliary battery problems can mask themselves as various electrical glitches. For a proper diagnosis, would you mind sharing: Current mileage, When the issues first appeared, Any recent electrical upgrades or modifications, Specific error codes if you have them, Whether problems occur more during cold starts This information would help determine if your symptoms match what I experienced and confirm if its truly an auxiliary battery issue.

Auxiliary battery replacement completely resolved my electrical problems. Currently at 157070 KM and just had my regular service done last month. The workshop performed power management tests during diagnostics and confirmed significant voltage drop during cold starts. The auxiliary battery was indeed the culprit, causing cascading electrical faults across multiple systems. Getting this fixed early prevents more serious electrical issues down the line. Through forum discussions, many RS6 owners reported similar symptoms being resolved with a new auxiliary battery. The actual repair time was quite quick once the diagnosis was confirmed.

Thanks for the update on your RS6 electrical issues. The symptoms and resolution exactly mirror what I experienced with my RS7. Power management issues are quite common in these models when the auxiliary battery starts failing. Mine also showed the telltale voltage drop during cold starts, and the battery replacement cleared up all those cascading electrical faults. Regular service checks on the auxiliary battery system are now part of my maintenance routine to catch any early signs of battery failure. The quick resolution through battery replacement saved me from potential long-term electrical system damage. At your mileage point, its actually quite common to need an auxiliary battery replacement, the power management system puts significant strain on these components over time. For anyone else reading who experiences similar starting problems or electrical glitches, getting a proper voltage test on both main and auxiliary batteries should be the first diagnostic step. A failing auxiliary battery often triggers multiple error codes that can be misleading if not properly diagnosed.

The auxiliary battery issue that affected my RS6 indeed proved identical to others in the forum. After 157070 KM, regular service monitoring failed to catch the early signs of voltage drop during engine start sequences. The workshop diagnostic tests revealed significant power management issues stemming from auxiliary battery degradation. The battery replacement process took less time than expected and resolved all electrical problems, including those unusual error messages and starting issues. Total repair cost was similar to other reports at around 290 Euro, which seems standard for this type of battery malfunction. For those following this thread with similar symptoms, the key indicators were: Multiple electrical system errors, Inconsistent engine start performance, Dashboard warning messages, Voltage fluctuations during cold starts Based on feedback from other RS6 owners and my personal experience, addressing auxiliary battery failure early prevents more extensive electrical system complications. The improvement in overall electrical system performance after replacement confirmed this was the right diagnosis and repair path.