Amarok Electrical Gremlins: Bad Alternator Warning Signs

I had a very similar issue with my 2010 VW Transporter, and as someone with moderate car repair experience, these symptoms immediately point to potential charging system problems. Started exactly like yours, dimming lights, rough starts, and the battery seeming to struggle. Initially thought it was just battery health issues, but the symptoms persisted even after basic checks. Took it to my workshop where they ran a comprehensive charging system diagnostic. Turned out the alternator issue was actually secondary, the main problem was a failing battery that was putting extra stress on the alternator. The battery tested well below capacity, despite looking fine externally. The fix included: Complete battery replacement, Testing of alternator output, Cleaning and securing all battery terminal connections, Full charging system verification Total cost was 290€ and it resolved all electrical issues completely. The workshop explained that letting a failing battery go too long can damage other electrical components. Before suggesting specific solutions for your case, could you share: How old is your current battery? Have you noticed these issues more during cold starts? Does the problem get worse when running multiple electrical components? Any check engine or battery warning lights? This information would help determine if your situation matches what I experienced or points to something different.

Just had my 108681km service last month. Thanks for that detailed response. Before trying a full battery replacement, I did some additional testing with a multimeter yesterday. Getting 12.1V at idle and 13.8V with the engine running, which seems borderline. Will definitely have my workshop check the battery health thoroughly. Your experience with the failing battery causing alternator stress makes sense given my symptoms. The issues do get significantly worse when running the AC and headlights together. Currently running the original battery from 2012, so its definitely due for evaluation. Are these voltage readings consistent with what you saw before your repair?

Definitely familiar with those voltage readings, they match almost exactly what I saw with my Transporter before the battery replacement. At 12.1V with the engine off, your battery voltage is showing classic signs of being undercharged, just like mine was. Running multiple electrical loads is a reliable test for charging system issues. When my battery was failing, the voltage regulator tried compensating but couldnt maintain stable power, especially with AC and lights running simultaneously. The stock battery lasting since 2012 is impressive, but matches the typical lifespan pattern. My original one also made it about 10 years before the electrical problems started. The low voltage readings at idle particularly mirror my experience, a healthy system should maintain closer to 12.6V at rest and 14.2-14.7V while running. A full charging system diagnostic would verify, but based on the identical symptoms and readings, sounds like your battery is following the same deterioration pattern mine did. Getting it checked now could prevent the alternator strain issues I experienced. Worth noting these voltage patterns often indicate battery cell degradation rather than just low charge, exactly what my workshop found during testing. The inconsistent power delivery to electrical systems matches this diagnosis too.

Based on your readings and feedback, I will get the battery professionally tested this week. Those voltage numbers seem concerning, especially since theyre notably lower than the ideal ranges you mentioned. Makes complete sense about wanting to catch this before it starts affecting the alternator. Just checked the battery manufacturing date, November 2012, so your point about typical lifespan really hits home. The similar voltage readings between our cases has me convinced this is likely the root cause of my electrical problem. The voltage drop under load with AC and lights matches your experience too closely to ignore. Getting intermittent electrical issues that align with what you described before your battery replacement. Really helpful having your real-world comparison, particularly those specific voltage benchmarks. Will report back once the workshop runs their diagnostics on the charging system and battery health. Thanks for helping narrow down the likely culprit.