VW Caddy Battery Drain Causes Multiple Electrical Fails

I dealt with nearly identical electrical system issues on my 2012 VW Touran last year. With some experience working on VWs, I recognized the symptoms you described, they closely match what I encountered. The flickering lights and weak starts initially made me think it was just a dead battery, but the workshop diagnosed a faulty battery sensor. This sensor monitors battery charge state and controls the charging system. When it fails, it can cause erratic electrical behavior and eventually lead to battery failure. The repair involved replacing the battery sensor and performing a full electrical system diagnostic. Total cost was 315€ including parts and labor. Since the fix, all electrical issues disappeared and the car starts perfectly. Before jumping to conclusions though, could you share: How old is your current battery? Are the issues more noticeable when its cold? Does the battery warning light come on? Have you noticed any correlation between using specific electrical accessories and the symptoms? This information would help determine if your Caddy is facing the same battery sensor issue or if theres another electrical system problem at play.

Just had my latest service at 144335km. The battery in my Caddy is original from 2014, and yes, the issues definitely get worse in cold weather. The battery warning light flashes occasionally, especially when using the heated seats or rear window defroster. After checking voltage myself, readings show 11.2V when running, which indicates serious battery drain or charging issues. The symptoms match what you experienced with the battery sensor. Definitely worth investigating since my electrical system shows similar erratic behavior. The battery voltage dropping while running suggests the charging system isnt working properly. Thank you for sharing the repair details and cost breakdown. Will get the battery sensor checked along with a full electrical system diagnostic to identify the root cause.

Based on those voltage readings, this is definitely pointing towards a charging system issue rather than just a heavily discharged battery. When I had my Touran serviced, the running voltage was similarly low at 11.4V, a properly functioning charging system should maintain around 13.8-14.2V. The original battery being 9 years old is concerning. Even with perfect charging conditions, most car batteries only last 5-7 years. The low battery voltage combined with the aging battery creates a compound problem, the weak charging system isnt able to properly charge an already compromised battery. In my case, replacing just the battery sensor didnt solve the complete issue. The workshop found the alternator was also underperforming, leading to insufficient charging. They ended up replacing both the battery sensor and alternator, plus installing a new battery since the old one was damaged from chronic undercharging. Would strongly recommend getting this addressed soon. Extended operation with a discharged battery and faulty charging system can damage other electrical components. The total repair cost in my case came to 890€, but preventing cascading electrical failures made it worthwhile.

Thanks for explaining those details about your battery system problems. Your Caddy having the original 2014 battery definitely raises red flags, especially with that 11.2V reading while running. Combining this with the cold weather sensitivity and warning light behavior when using high-draw accessories really suggests a failing charging system. I will have the shop do a complete diagnostic of the charging system, focusing on both the battery sensor and alternator as you suggested. The voltage readings you shared give me a good baseline to compare against, my 11.2V is clearly far below the proper 13.8-14.2V charging range. Makes total sense about the compound effect of an aging battery and faulty charging system. Your repair cost breakdown is helpful for budgeting. While 890€ is significant, preventing wider electrical damage seems worth the investment. I will schedule service this week before any other components get affected by the battery drain issues. Thanks again for the detailed troubleshooting guidance. The battery sensor/alternator combination issue you experienced provides a solid direction for my mechanic to investigate.