The 2009 Audi A4 uses a 12-volt automotive battery. In most configurations, it's a Group 48 (also called H6) lead-acid unit; if your car has the Start-Stop system, it may use an AGM 12-volt battery of the same size.
Battery configurations and why they vary
In the B8-generation A4 released around that time, battery location and type can vary by market and options. The standard battery is a 12V lead-acid unit used to power electronics when the engine is off; cars with Start-Stop require a more robust battery and often use an AGM (absorbed glass mat) battery to tolerate repeated cycling.
- Group 48 / H6 (standard lead-acid): 12V; commonly about 60–70 Ah; typical cold-cranking amps (CCA) around 600–700 A, depending on manufacturer.
- AGM variant (Start-Stop): 12V; commonly Group 48 AGM or equivalent; typically around 60–80 Ah and 700–800 A CCA, with higher resistance to deep discharging.
Because the exact spec can depend on the vehicle's market, trim, and whether Start-Stop is fitted, always verify with the battery label, owner’s manual, or a dealer for your specific car.
Locating and verifying the battery in your car
To confirm the exact size and rating for your particular 2009 A4, inspect the battery and consult official documentation. Here are steps to verify:
- Check the battery top label for group size (for example, "Group 48" or "H6") and CCA rating.
- Consult the owner's manual or service bulletin for your trim and market to confirm the recommended battery specification.
- If in doubt, provide your VIN to a local Audi dealer or an authorized parts retailer to obtain the exact replacement specification.
Take note that in some markets the Start-Stop-equipped cars use an AGM battery, which is not the same as standard flooded lead-acid batteries and may require a compatible replacement to maintain system performance.
Summary
The 2009 Audi A4 commonly uses a 12V battery. Most non-Start-Stop models employ a Group 48 / H6 lead-acid unit, while Start-Stop versions typically use an AGM 12V battery of the same size. Always verify the exact spec on the battery label or with Audi using your VIN, as configurations can vary by market and trim.