What Size Battery Does the Audi A4 Use?

The Audi A4 typically uses a 12‑volt AGM (Absorbent Glass Mat) battery in the Group 47 (H5) or Group 48 (H6) size for most recent model years, but the exact battery size, capacity, and specification depend on the model year, engine, and equipment such as start‑stop or mild-hybrid systems. Understanding your specific A4’s configuration is essential before purchasing a replacement battery.

Why the “Right” Battery Size Matters for the Audi A4

The Audi A4 is heavily dependent on electronic systems, from start‑stop technology and infotainment to driver-assistance features. Because of that, the battery is not just a generic 12‑volt unit—it must match specific size, capacity, and technology requirements to ensure reliable operation and to avoid issues with the car’s electrical management system.

Common Battery Sizes for Recent Audi A4 Models

Different generations and trims of the Audi A4 use slightly different battery sizes. Most modern A4s (especially with start‑stop) use AGM batteries, while older, simpler models may use EFB or traditional flooded batteries, depending on region and equipment level.

Typical Battery Sizes by Generation (Approximate Guide)

The following list gives a general overview of the most commonly specified battery groups and technologies for Audi A4 models by generation. Always verify your specific vehicle with its VIN or by checking the existing battery label.

• B9 (2017–present, including 2024 A4):
  

  • Most 2.0 TFSI and TDI models with start‑stop: 12 V AGM, Group 48 (H6) or Group 47 (H5), typically around 70–80 Ah, ~680–800 A (EN/CCA).
  • Higher‑spec or S line models with more electrical equipment: 12 V AGM, usually Group 48 (H6), ~80 Ah.
  • Mild‑hybrid versions (where available, mainly in Europe): retain a 12 V AGM (often H6) plus a separate 12 V lithium-ion or 48 V system battery for the mild hybrid system.

• B8 / B8.5 (2009–2016):
  

  • Common fitment: 12 V AGM, Group 48 (H6) or sometimes Group 49 (H8) in some markets and higher-spec models.
  • Capacity usually 70–95 Ah depending on engine (2.0 TFSI, 3.0 TDI, etc.) and equipment.
  • Most start‑stop models: AGM required; non‑start‑stop models in some regions may use EFB or conventional flooded batteries, but replacing with AGM is often recommended for longevity.

• B7 (2005–2008):
  

  • Commonly: 12 V flooded lead‑acid or AGM, Group 48 (H6) or Group 94R (in some markets).
  • Capacities typically in the 70–80 Ah range.

• B6 (2001–2005) and older:
  

  • Primarily 12 V conventional lead‑acid batteries; physical size similar to Group 48 or 94R depending on market.
  • Lower electronic load compared with modern cars, so capacity requirements are less demanding, often around 60–72 Ah.

These ranges reflect common OEM and aftermarket configurations but are not a substitute for checking the exact specification for your vehicle. Market differences (North America vs. Europe vs. other regions) and optional equipment can change the original battery size.

How to Identify the Correct Battery Size for Your A4

Because trim levels, regional specs, and options like start‑stop or mild-hybrid systems affect the battery, there are several reliable ways to confirm what your specific Audi A4 needs.

Check the Existing Battery Label

The easiest starting point is to look at the battery currently installed in the car, assuming it is original or correctly specified.

• Open the trunk or hood (location varies by year: many A4s have the main battery in the trunk, under the floor, near the spare wheel; some earlier models place it in the engine bay).
• Read the top or side label for:
  

  • Battery type: “AGM,” “EFB,” or “Pb”/“Lead‑acid.”
  • Capacity: usually in ampere‑hours (Ah), e.g., 70 Ah, 80 Ah, 95 Ah.
  • Cold cranking amps (CCA or EN): e.g., 680 A EN, 760 A CCA.
  • Physical group/size code: such as 47 (H5), 48 (H6), 49 (H8), or regional codes like 94R.

• Note the brand and part number (e.g., VARTA, Exide, Audi/VW part number like 8K0…, 8W0…, etc.).
• Match replacement to these specs as closely as possible, prioritizing battery type (AGM vs EFB vs flooded) and size group.

Confirming the label details helps you avoid under‑sized or incompatible batteries that may cause error messages or reduced lifespan.

Use the Owner’s Manual and VIN-based Lookup

If you suspect the current battery may not be original or if it’s missing/illegible, the owner’s documentation and VIN lookup tools are the next best source.

• Owner’s manual:
  

  • Check the maintenance or technical data section.
  • Look for entries under “Battery,” “Electrical system,” or similar headings.
  • Often lists minimum Ah, battery type (AGM/EFB), and sometimes the Audi part number.

• VIN-based online catalog:
  

  • Use Audi’s official parts catalog or reputable third-party catalogs (e.g., from major battery manufacturers or parts retailers).
  • Enter your VIN; the system returns the correct OE battery size and part number (or several options if your exact spec differs by equipment).

• Dealer confirmation:
  

  • An Audi dealer can scan your VIN and specify the original battery group, capacity, and technology.
  • This is helpful for newer models with complex electrical architectures, such as B9 and any mild‑hybrid variants.

Cross‑checking manual information with VIN-based data reduces the risk of fitting an incorrect battery, which can affect both reliability and warranty considerations.

Battery Technology in the Audi A4: AGM, EFB, and Standard Lead‑Acid

Modern Audi A4 models often require advanced battery types due to start‑stop systems and high electrical demand. Replacing like-for-like technology is critical for proper operation.

AGM Batteries: Standard for Most Modern A4s

AGM (Absorbent Glass Mat) batteries are the default choice for most B8 and B9 Audi A4s, especially those with start‑stop features.

• Deep-cycle tolerance: Better at handling frequent discharge/recharge cycles caused by start‑stop and urban driving.
• Higher power density: Supplies strong starting current while maintaining stable voltage for sensitive electronics.
• Spill-proof design: Electrolyte is absorbed in fiberglass mats, reducing leakage risk—important for trunk-mounted batteries.
• Longer service life (when properly managed): Often outlasts conventional flooded batteries under demanding conditions.

When your A4 originally came with an AGM battery, using a conventional flooded replacement is not recommended and can lead to early failure and system warnings.

EFB and Conventional Flooded Batteries in Older or Simpler A4s

Some older or lower-spec A4 models may use EFB (Enhanced Flooded Battery) or standard flooded batteries, particularly where start‑stop is absent.

• EFB batteries:
  

  • Designed as an intermediate solution between conventional and AGM.
  • Better cycle life than standard flooded, but not as robust as AGM.
  • Sometimes used in vehicles with less demanding start‑stop strategies.

• Conventional flooded batteries:
  

  • Found in older generations (B6, early B7) with simpler electronics.
  • Cheaper, but less tolerant of deep cycling and heavy accessory loads.
  • Still must match physical size and minimum Ah/CCA requirements.

Upgrading from a conventional or EFB battery to an AGM is usually acceptable (and often beneficial), provided the size and ratings match, but the reverse—downgrading from AGM—is not advisable.

Battery Location and Installation Considerations

Knowing where the battery is located and what is required for installation is important, particularly because many Audi A4 models require battery “coding” or registration after replacement.

Where the Battery Is Located

The location affects access and the procedure for replacement.

• B9 and many B8 models:
  

  • Primary 12 V battery usually located in the trunk, under the floor panel.
  • Secured with a clamp and sometimes covered by trim or plastic shields.

• Some older generations (B6/B7):
  

  • Battery may be located in the engine bay, typically near the firewall or right-hand side.
  • Access is more straightforward but may still involve removing covers.

• Mild‑hybrid variants:
  

  • In addition to the main 12 V battery, may have an extra 12 V or 48 V battery located in a separate compartment.
  • Servicing high‑voltage or 48 V components should be left to trained technicians.

Understanding your battery’s location helps you plan for tools, time, and potentially professional assistance, especially on later models with more complex layouts.

Coding and Registering a New Battery

Most modern Audi A4 models use a battery management system (BMS) that expects specific data about the installed battery. Swapping the battery without updating the system can cause charging issues or reduce the new battery’s lifespan.

• What coding/registration involves:
  

  • Entering new battery details (capacity, technology, sometimes manufacturer and serial number) into the car’s control module.
  • Resetting the battery adaptation so the car adjusts its charging strategy to the new battery.

• Tools required:
  

  • Professional diagnostic tools such as VCDS (VAG‑COM), ODIS, or compatible aftermarket scanners.
  • Some independent garages and many battery retailers offer this service for a fee.

• Consequences of skipping coding:
  

  • Incorrect charging rates (over‑ or under‑charging).
  • Reduced battery life and potential start‑stop malfunctions.
  • Possible warning lights or error messages related to the electrical system.

For most B8 and B9 Audi A4s, having the new battery correctly coded or registered is strongly recommended and often considered standard procedure by dealers.

Key Specifications to Match When Buying a Battery

Beyond just “size,” several technical parameters need to align with your Audi A4’s requirements to ensure trouble-free operation.

Dimensions, Capacity, and Performance Ratings

Battery fitment is a combination of physical and electrical specifications, all of which should be considered together.

• Physical size / group code:
  

  • Common for A4: Group 47 (H5), Group 48 (H6), sometimes Group 49 (H8) or 94R.
  • Must fit the battery tray and clamp and allow secure mounting.

• Capacity (Ah):
  

  • Typical range: around 70–95 Ah for modern A4s.
  • Match or slightly exceed the original Ah rating; don’t go significantly lower.

• Cold Cranking Amps (CCA or EN):
  

  • Important for reliable cold-weather starting.
  • Values often between ~640–800 A EN for A4 petrol and diesel engines.
  • Equal or higher CCA than OEM is usually safe; lower CCA is not recommended.

• Terminal layout and polarity:
  

  • Ensure positive and negative terminals are on the correct side for your cables.
  • Most A4s use standard European layout with recessed or top posts.

Matching these specifications ensures proper fit, reliable starting, and correct interaction with the vehicle’s charging and management systems.

OEM vs Aftermarket Battery Options

Owners can choose between genuine Audi/VW-branded batteries and reputable aftermarket brands, each with trade‑offs in cost and warranty.

• OEM (genuine) batteries:
  

  • Come with exact specifications and are fully compatible with Audi’s BMS.
  • Often manufactured by major battery companies (VARTA, Banner, Exide) under Audi branding.
  • Tend to be more expensive but may offer straightforward warranty handling through the dealer network.

• Aftermarket batteries:
  

  • Offered by leading brands (e.g., VARTA, Bosch, Exide, Yuasa, Interstate, etc.).
  • Can match or exceed OEM specs at a lower cost.
  • Must be carefully cross‑referenced by group size, Ah, CCA, and technology (AGM/EFB).

• Warranty and support:
  

  • Check warranty length (often 3–5 years on premium AGM models).
  • Confirm that the seller or installer can perform coding/registration if required.

Choosing a quality OEM-equivalent AGM battery that matches all critical specifications is usually the best balance of cost, performance, and reliability for most Audi A4 owners.

Quick Reference: What Most Audi A4 Owners Will Need

While individual requirements vary, there are common patterns that cover the majority of current and recent Audi A4s on the road today.

Most Common Configurations by Era

The following bullets summarize typical battery setups that apply to many—but not all—Audi A4s, especially in Europe and North America.

• 2017–2024 Audi A4 (B9):
  

  • Battery type: 12 V AGM.
  • Size: Group 48 (H6) in many cases; some use Group 47 (H5).
  • Capacity: roughly 70–80 Ah; CCA commonly around 680–800 A EN.

• 2009–2016 Audi A4 (B8/B8.5):
  

  • Battery type: AGM for start‑stop models; some non‑start‑stop may use EFB or flooded.
  • Size: Often Group 48 (H6), sometimes Group 49 (H8) depending on engine and region.
  • Capacity: approx. 70–95 Ah, higher on diesel and high‑spec trims.

• 2005–2008 Audi A4 (B7) and earlier:
  

  • Battery type: Conventional flooded or AGM, depending on specification.
  • Size: Commonly Group 48 (H6) or European equivalents such as 94R.
  • Capacity: Usually around 60–80 Ah, depending on engine and equipment.

These patterns are meant as a starting point. Because Audi offers numerous engine options and packages, always verify the exact battery type and size for your specific VIN before buying a replacement.

Summary

The Audi A4 generally uses a 12‑volt AGM battery, most commonly in the Group 47 (H5) or Group 48 (H6) size for recent B8 and B9 models, with capacities typically in the 70–80 Ah range and cold cranking ratings around 680–800 A EN. Older generations may use conventional flooded or EFB batteries in similar physical sizes but with somewhat lower electrical demands. The precise battery size and specification for any given A4 depend on model year, engine, market, and equipment such as start‑stop or mild-hybrid systems. The safest approach is to check the existing battery label, consult the owner’s manual, or use a VIN-based parts lookup, and then ensure that the replacement matches in battery technology, group size, capacity (Ah), and CCA. For modern A4s, having the new battery correctly coded or registered to the vehicle’s battery management system is essential for optimal performance and longevity.