Audi Q5 Voltage Issues Point to Failing Regulator

Similar issues occurred with my 2012 Audi Q3 2.0 TFSI. Having some experience with charging system problems, I initially suspected the battery too. After replacing the battery twice like you did, the workshop diagnosed a failing alternator causing inconsistent charging. The alternator wasnt delivering proper voltage to maintain battery health, leading to repeated battery drain issues. The voltage regulator, which is part of the alternator assembly, was indeed the root cause. The repair involved replacing the complete alternator unit, costing 290 Euro including labor. Since then, the low voltage symptoms completely disappeared, no more slow cranking or electrical glitches. Could you share: Current battery voltage readings while running? Does the battery warning light come on? Any recent electrical upgrades or accessories installed? Have you noticed the issues getting worse during rainy weather? These details would help determine if your Q5 is facing the same alternator issue my Q3 had. A proper diagnostic of the charging system should reveal if the alternator is failing to maintain adequate charge.

Last serviced at 62743 KM with full electrical system check. The voltage drop symptoms in my case turned out to be related to a corroded ground wire connection near the transmission mount, not the alternator. A voltage test showed irregular charging patterns that initially pointed to the alternator, but deeper inspection revealed the ground wire issue. I suggest having a full electrical system diagnostic done. My repair cost was 180 Euro which included cleaning all battery terminals and replacing the damaged ground wire. The charging system has worked flawlessly since the fix three months ago. My workshop confirmed this is a known weak point in the electrical system on these models. A proper ground connection is critical for maintaining stable voltage across all systems.

Thanks for sharing those details about the ground wire fix. That matches what I ultimately discovered with my Q3 too, I jumped to conclusions about the alternator without checking all the basics first. After seeing your post, I did a more thorough inspection and found corrosion at multiple ground points, not just near the transmission. The voltage regulator readings were misleading because of these bad grounds. A professional electrical diagnostic revealed the same irregular charging pattern you mentioned. The complete ground wire service on my Q3 came to 210 Euro. Since fixing those connections, the low voltage symptoms have completely disappeared. No more dimming lights, slow starts, or system glitches that made me think I had alternator issues. Your case really highlights why proper diagnosis is crucial, what seems like a major alternator issue could be a relatively simple ground connection problem. Regular inspection of ground points should probably be part of standard maintenance on these models to prevent voltage drop issues from developing. Have you noticed any other electrical quirks since the repair that might point to remaining ground points needing attention?

The alternator issue diagnosis path others shared matches my experience. After running more tests, here are my current readings and situation updates: Battery voltage while running stays at 13.8V, so the charging system itself seems okay. No battery warning lights have appeared. The only recent electrical change was adding LED interior lights, but issues started before that. The problems definitely get worse in wet weather, which supports the ground connection theory mentioned. The transmission ground wire check makes sense given my symptoms. I will have my mechanic do a complete ground point inspection rather than jumping straight to alternator replacement. The low voltage symptoms match the ground connection problem exactly, especially the weather-related issues. Getting the full electrical diagnostic done is clearly the right next step before replacing major components. These posts saved me from an unnecessary alternator replacement that might not have fixed the actual problem. Will update once the ground connections have been inspected and tested.