Audi A1 Voltage Drop Mystery Plagues Electronics

As someone with moderate experience working on modern cars, I faced nearly identical issues with my 2020 Audi A3 last winter. The symptoms you describe match my experience exactly, from the weak starts to the voltage fluctuations when running multiple systems. After monitoring the charging system myself, I discovered the battery terminals had developed corrosion, leading to poor connections and irregular power supply. Despite the battery health appearing good initially, further testing revealed it was heavily discharged and ultimately defective. The workshop performed: Complete battery diagnostic, Charging system evaluation, Voltage regulator testing, Replacement of the battery, Terminal cleaning and protection Total cost was 290 Euro, which included parts and labor. The investment was worth it as it resolved all electrical issues completely. Before suggesting specific solutions, could you share: How old is your current battery? Does the battery warning light appear on your dashboard? Have you noticed any alternator whining sounds? What were the exact voltage readings from your diagnostic scan? This information would help determine if your issue mirrors mine or points to a different underlying problem with the charging system.

Latest service was completed at 10000 KM with no major issues found. Thanks for sharing your experience. Like you mentioned, I also noticed the voltage drop is more severe when running multiple electrical components. The battery warning light occasionally flickers during cold starts. No whining sounds detected from the alternator area. My diagnostic scan showed battery voltage fluctuating between 11.8V and 13.2V while idling, dropping below 11V under load. The battery itself is original from 2022. Will have the battery terminals checked for corrosion before proceeding with more extensive repairs.

I mentioned cleaning the terminals in my earlier reply, but based on your voltage readings, this seems more serious than just terminal corrosion. In my A3 case, the readings were similar, the voltage drop below 11V under load is particularly concerning and points to a potential alternator issue more than just battery problems. Looking back at my repair experience, I initially focused too much on the battery health alone. The alternator should maintain around 13.8-14.4V while running, so your 13.2V max reading suggests the charging system isnt performing optimally. Given your car is newer than mine was when I had issues, Id recommend getting the alternator tested before replacing the battery. My mistake was replacing the battery first without checking the alternator, which ended up needing attention anyway. A proper voltage drop test across the charging circuit would help pinpoint if its truly an alternator issue or an electrical problem elsewhere in the system. This typically costs around 50 Euro for diagnostic testing. Since youre seeing similar symptoms to what I experienced, but with a newer battery, focus on the charging system components first rather than assuming its just battery-related like I initially did.

Thanks for the detailed follow up. The voltage readings and fluctuating battery warning light really help explain whats happening. Will get the battery terminals checked first but based on your experience, Im preparing for potential alternator work. Made an appointment at a local shop tomorrow to run a complete charging system diagnostic. Your A3 case especially caught my attention since the symptoms match so closely, particularly the voltage drop under electrical load. Though my battery is relatively new, the alternator issue angle makes a lot of sense given the test readings. My scan showed 11.8V-13.2V at idle and under 11V with accessories running. From what youve shared about proper alternator output being 13.8-14.4V, its clear something isnt right with the charging system. Will update once I get the test results and know if its truly an alternator issue or related electrical problem. Thanks again for helping me avoid going down the battery replacement path first without checking the whole system. The 50 Euro diagnostic test sounds worth it to pinpoint the exact cause.