Your Audi A3 8Y shouldn’t be flat by morning. Here’s how a mechanic tracks down a parasitic draw and what it means for driving.
It's frustrating: your Audi A3 8Y was fine last night, but this morning the battery is flat and the doors barely unlock. That is the classic sign of a parasitic electrical draw — something on the car is staying awake after shutdown. On a healthy A3 8Y, the electrical system should go to sleep within 30 to 60 minutes and settle below roughly 50 mA (0.05 A). Anything above that can drain an AGM battery overnight, especially if you mostly do short trips.
