Outback's Dead Battery Despite New Replacement

Had nearly identical symptoms on my 2007 Legacy GT. After installing a new battery, the problems persisted just like yours. Despite the initial battery terminal cleaning and alternator test showing ok, the charging system was not functioning properly. The actual fix required: Complete power supply diagnostic, Replacement of corroded battery cables, New voltage regulator, Rebuilt alternator due to worn brushes The battery voltage was dropping to 11.8V while running, when it should maintain 13.5-14.4V. This was causing the dim lights and hard starts you described. The alternator issue was serious since it wasn't properly charging the battery, leading to deeply discharged cycles that damage batteries. A proper diagnosis needs specialized testing equipment to measure charging system output under load. The alternator may test fine at idle but fail under real driving conditions. Would suggest getting a full charging system diagnostic at a shop that specializes in electrical repairs, as this requires expertise beyond basic service centers. Make sure they check: Battery load test, Alternator output at various RPMs, Voltage drop across cables, Parasitic draw test

Thanks for sharing your Legacy GT experience. You described exactly what my Outback is going through right now. Low voltage issues are really frustrating, especially with multiple electrical problems popping up. The voltage regulator replacement and alternator rebuild you mentioned makes a lot of sense, since my voltage readings are also way below the normal 13.5V range. The battery terminal connections looked a bit crusty when I checked them too. Would you mind sharing what the total repair cost was for your fix? Also curious if youve had any voltage drop issues since getting it all sorted out? Just trying to budget and make sure I address everything at once.

After completing all the repairs mentioned in my previous post, I havent experienced any further electrical problems or voltage drop issues. The battery voltage now consistently stays within the proper 13.5-14.4V range during operation. The total repair bill came to 290€ for addressing the heavily discharged battery situation. This included thorough power supply diagnostics, cleaning connections, and fixing the related components. Considering the comprehensive nature of the fix, it was worth the investment to restore proper battery health and charging system function. Looking back, the key was having a specialist properly diagnose the entire electrical system rather than just testing individual components. The battery voltage is now stable, and the car starts perfectly every time without the previous symptoms. A proper diagnosis and fix can prevent repeated battery failures and more expensive repairs down the road.

Thanks for the helpful advice. I took my Outback to an electrical specialist last week after reading these responses. The voltage regulator turned out to be the main culprit, just as suggested. The shop did a complete power supply diagnostic which showed my alternator was only putting out 11.9V, way below normal. They found corroded wiring near the voltage regulator that was causing the alternator issue. After replacing both parts and cleaning all connections, my battery voltage now holds steady at 14.2V. The total repair came to 340€, which included: Full electrical system testing, New voltage regulator, Wiring repairs, Deep cleaning of all battery connections The car starts instantly now and all electrical problems have disappeared. The difference in performance is amazing, no more dim lights or struggling starter. Really glad I got a proper diagnosis instead of just replacing parts out of nowhere. Definitely worth finding a shop that specializes in electrical problems rather than going to a general service center. They caught issues the previous mechanic missed completely.