What Size Battery Do You Need for a 2009 Audi A4?
The correct replacement battery for most 2009 Audi A4 models is a Group H6 (also known as Group 48) with around 70–80 Ah capacity and at least 680–800 CCA, but exact size and specs can vary by engine, equipment, and climate, so checking the existing battery label or VIN-based parts lookup is essential.
Contents
Understanding the 2009 Audi A4 Battery Requirements
The 2009 Audi A4 (B8 generation) uses a front‑mounted, AGM‑compatible battery engineered to support high electrical demand from features such as electric power steering, advanced infotainment, and, on some models, start-stop–like efficiency systems in later years. While there is a “typical” size most owners will use, Audi’s options list and regional packages mean that one size does not fit absolutely all cars, making verification crucial.
Typical Battery Group Sizes and Specs
To select the correct battery, it helps to understand the most common group sizes and specifications Audi and major battery manufacturers list for the 2009 A4. The following list outlines the typical fitments used in North America and Europe and what they mean for real-world use.
- Most common fitment: Group H6 / 48 – This is the standard size for many 2009 Audi A4 2.0T and 3.2 models. Dimensions are approximately 11.0" x 6.9" x 7.5" (278 x 175 x 190 mm). Typical ratings:
- Capacity: ~70–72 Ah
- Cold Cranking Amps (CCA): ~680–800 CCA (or 640–760 A EN in Europe)
- Type: AGM recommended; high‑quality flooded accepted if vehicle is not heavily optioned and climate is mild
- Larger optional fitment: Group H7 / 94R – Found on some cars with higher electrical loads (e.g., more options, colder‑climate packages) or when a prior owner upgraded. Dimensions are about 12.4" x 6.9" x 7.5" (315 x 175 x 190 mm). Typical ratings:
- Capacity: ~80–95 Ah
- CCA: ~760–900 CCA
- Type: Often AGM, especially from premium brands
- European designation equivalents – In Europe, the same physical sizes may be listed under codes such as 70Ah/720A EN or 80Ah/800A EN with H6/H7 sizing noted in technical data rather than on the store label.
- Polarity and terminals – The 2009 A4 uses standard top posts with negative on the left when the posts face you (DIN / European orientation). Mismatched polarity can prevent installation or cause damage if connected incorrectly.
- Height constraint – The battery tray and under‑hood cover demand a standard 190 mm height; taller truck or “deep‑cycle” batteries may interfere with covers or wiring.
These sizes cover what the large majority of 2009 Audi A4 owners will encounter; however, subtle differences in trim and market can make verification of group size, CCA, and Ah rating essential before purchase.
AGM vs. Flooded: Which Type Is Best?
The 2009 Audi A4’s electrical system and location of the battery in a relatively confined under‑hood area make a strong case for AGM (Absorbent Glass Mat) technology, though not every original car left the factory with AGM. Understanding the trade‑offs will help you choose between AGM and conventional flooded designs.
- AGM advantages
- Better resistance to vibration and heat under the hood.
- Improved performance under high electrical load (heaters, defrosters, infotainment, night driving).
- Slower self‑discharge, helpful for cars that sit for several days or more.
- Spill‑resistant construction, safer in case of damage and better in tight spaces.
- AGM considerations
- Higher purchase price than a comparable flooded battery.
- Charging system should be in good condition; overcharging AGM can shorten its life.
- Conventional flooded batteries
- Lower initial cost and widely available.
- Can still meet Audi’s specs if you choose the right size and CCA for the car and climate.
- Typically shorter lifespan in high‑heat, high‑load scenarios compared to AGM.
- What most suppliers recommend
- Major aftermarket catalogs (Bosch, Varta, Exide, Interstate, etc.) generally recommend an AGM H6/48 or H7/94R for 2009 A4 models to match or exceed OEM performance.
In practice, many owners opt for an AGM Group H6 or H7 for longevity and reliability, especially if they frequently use accessories or drive in extreme temperatures, though a quality flooded battery still works in milder, everyday conditions.
How to Confirm the Right Battery for Your Specific A4
Because options and regional differences can affect what was originally installed, confirming the correct size for your individual 2009 Audi A4 prevents fitting problems and avoids buying an under‑ or over‑spec’d battery.
- Check the existing battery label
- Look for the group size (H6, 48, H7, 94R), capacity (Ah), and CCA/EN rating printed or stamped on the top or side.
- If the car still carries its original or OEM‑equivalent battery, matching those specs is usually safest.
- Measure the battery tray
- Measure length, width, and height clearance if the old battery is missing or obviously wrong.
- Confirm that the battery hold‑down and side supports match the size you intend to install.
- Use VIN‑based parts lookup
- Dealers and many online parts catalogs can look up the correct battery specification using your VIN.
- This is especially useful if your A4 has unusual option levels or was delivered to a specific market.
- Consider engine and equipment level
- 2.0 TFSI vs. 3.2 V6 models may have slightly different recommendations in some catalogs.
- Cars with more electrical accessories (heated seats, advanced audio, factory navigation) benefit from higher Ah and CCA.
- Account for climate
- Cold climates: lean toward higher CCA (closer to 800–900 CCA) and AGM construction.
- Hot climates: quality brand and proper heat resistance are more important than maximum CCA.
By combining a visual inspection with VIN‑based confirmation and climate considerations, you can confidently pick a battery that fits physically and performs reliably in your particular 2009 A4.
Battery Registration and Electronics Considerations
Modern Audis increasingly monitor the battery through their energy management systems, and while the 2009 A4 is less demanding than newer models, it can still benefit from proper electronic handling when a new battery is installed.
- Battery registration/coding
- Later Audi models require “registering” a new battery via scan tool to reset charging parameters.
- For many 2009 A4s, battery coding is not as strict as on newer cars, but some scan‑tool procedures may still be recommended, especially if you change type (flooded to AGM) or capacity significantly.
- Avoiding voltage drops during swap
- Use a memory saver or keep doors closed and accessories off to avoid triggering faults.
- After installation, some systems (windows, sunroof) may need basic reinitialization via simple button procedures.
- Check for stored faults
- If you have access to VCDS or a similar diagnostic tool, scan for power‑related DTCs and clear them after replacement.
Handling the electronic side carefully helps your new battery integrate smoothly with the A4’s energy management, reducing the risk of odd electrical behavior or early battery fatigue.
Key Takeaways for a 2009 Audi A4 Battery
Choosing the correct battery size for a 2009 Audi A4 comes down to matching physical fit with adequate electrical performance, then tailoring the final choice to your climate and usage patterns.
- Most 2009 Audi A4s use a Group H6 / 48 battery, around 70–80 Ah and 680–800 CCA.
- Some higher‑load or upgraded cars may use a Group H7 / 94R with ~80–95 Ah and higher CCA.
- AGM is strongly recommended for durability and performance, though high‑quality flooded batteries are still used in some markets.
- Always confirm size and specs via the existing battery label, tray measurements, and VIN‑based lookup.
- Pay attention to correct installation, polarity, and any necessary electronic reset or registration.
With the right group size, capacity, and type confirmed for your specific vehicle, a quality H6 or H7 battery will keep your 2009 Audi A4 starting reliably and supporting its electronics for years to come.
Summary
For a 2009 Audi A4, the commonly correct battery is a Group H6 (Group 48), around 70–80 Ah and at least 680–800 CCA, with AGM construction preferred. Some cars, especially with heavier electrical loads, may use the slightly larger H7 (94R). Because trim level, market, and prior owner changes can affect what fits best, the safest approach is to match your current battery’s size and specs, verify with VIN‑based lookup, and choose a reputable AGM battery that meets or exceeds the original rating.
What size battery is in the 2009 Audi a4?
Duralast Group Size 49 H8 Battery H8-DL.
What battery do I need for my Audi?
Your owner’s manual should tell you what Audi battery you need – or you can check it instantly by using our battery search tool at the top of this page. Our battery test technicians can also advise you. Whatever the answer, we’re likely to have you covered.
How do I know my battery size?
You can check a battery’s size by looking for markings like mAh, Wh, or a BCI Group Size on the battery itself, in the device’s user manual, or by using online tools. For digital devices, you can often find the battery capacity in the device’s settings under an “About” or “Battery” section. For car batteries, the physical group size is printed on the battery’s label and is crucial for ensuring a correct fit in the car’s compartment.
This video demonstrates how to find battery information on an Android phone: 58sWiz of AppsYouTube · Apr 3, 2024
For portable electronics
- Check the label: Look for markings like mAh (milliampere-hours) or Wh (watt-hours) printed on the battery itself.
- Check the device settings: On many Android devices, you can find battery capacity in Settings > About phone > Battery or by searching for “battery information”.
- Check the manual: The device’s user manual will list the battery capacity or type.
For car batteries
- Check the battery label: Open the hood and look for the BCI Group Size printed on the label on top of the battery. This size is crucial for ensuring a physical fit in the car.
- Check the owner’s manual: The owner’s manual will specify the correct BCI Group Size and other details like cold cranking amps (CCA).
- Use online tools: Many auto parts stores offer online fitment finders where you can enter your car’s year, make, and model to find compatible batteries.
- Measure it yourself: While less reliable than the BCI size, you can measure the length, width, and height of the battery itself and compare them to online charts to find a corresponding group size.
This video demonstrates how to test a car battery using a multimeter: 59sClassic Car MaintenanceYouTube · May 31, 2024
Where is the battery in a 2009 Audi A4?
The 2009 Audi A4 battery is located in the trunk, underneath the spare tire. To access it, you will need to lift the floor mat in the trunk, remove the spare tire, and then you will be able to see and remove the battery.
You can watch this video to see how to access the battery compartment: 58sTotal TechnikYouTube · Jun 19, 2021
- Open the trunk: Use the button on the driver’s door panel to open the trunk.
- Lift the floor: Lift up the luggage compartment floor mat or cover to expose the spare wheel well.
- Remove the spare tire: Undo the central spindle or any other fasteners holding the spare tire and then lift the tire out of the car.
- Access the battery: The battery will be located underneath the spare tire, and you may need to remove some plastic covers to gain full access to it.
This video shows the location of the battery after removing the spare tire: 58sMotorCarNutYouTube · Feb 12, 2025
