What Kind of Battery Does a 2011 Audi S4 Take?

The 2011 Audi S4 typically uses a Group 48 (H6) AGM 12‑volt battery, around 70–80 Ah and 680–800 CCA, but owners should confirm exact specs using the vehicle’s build sticker, old battery label, or a fitment guide because equipment and market differences can slightly change requirements. This article explains the correct battery type, key specifications, and what to consider when replacing it.

The Standard Battery Type for a 2011 Audi S4

For most North American and European 2011 Audi S4 models, the factory-fit battery is an absorbed glass mat (AGM) type in the H6 / Group 48 size. Audi uses AGM because of the vehicle’s high electrical load, start‑stop–like demands in urban driving, and the need for stable voltage for sensitive electronics.

Typical OEM‑Equivalent Specifications

While exact OEM part numbers can vary by market and options, most 2011 S4 sedans and Avants are designed for a battery with the following characteristics:

• Battery group/size: H6 (also known as Group 48 in North America)
• Chemistry: AGM (Absorbent Glass Mat), maintenance‑free
• Voltage: 12 V
• Capacity: generally about 70–80 Ah (amp‑hours)
• Cold Cranking Amps (CCA): typically in the 680–800 CCA range
• Polarity: standard left‑positive, right‑negative layout for H6/48
• Location: trunk (boot) area, usually on the right side under trim

These specs ensure enough cold‑start performance for the supercharged V6 engine and stable operation for systems like the MMI, power seats, climate control, and safety electronics.

How to Confirm the Correct Battery for Your Specific S4

Because options, regional variations, and previous owner changes can affect what battery is currently in the car, it’s worth confirming the correct replacement rather than relying solely on generic fitment charts.

Check the Existing Battery Label

One of the most reliable ways to confirm fitment is to inspect the battery that’s currently in your S4, assuming it was installed correctly and is the proper type.

The following points can help you read and interpret the label on your existing battery:

• Group size marking: Look for “H6,” “L3,” or “48” stamped or printed on the label.
• Chemistry: It should say AGM, VRLA, or “Absorbent Glass Mat,” not just standard “wet” or “flooded.”
• Capacity: Measured in Ah—often 70 Ah, 72 Ah, or 80 Ah for this model.
• CCA rating: Listed as CCA or EN; it will normally be in the high 600s to 800s.
• Terminal layout: Confirm the positive terminal side matches the car’s cable arrangement.

If the label shows a different group size—like H7/94R—someone may have upgraded or changed the configuration, which can be acceptable if it physically fits and is correctly secured.

Use a Fitment Guide or VIN Lookup

For extra certainty, parts retailers and dealers often provide searchable fitment tools.

The following common methods can help verify compatibility beyond simply checking the current battery:

• Online parts catalogs: Enter “2011 Audi S4” along with body style and engine (3.0 TFSI) to get recommended group sizes and product lines.
• VIN lookup at a dealer: An Audi dealer can use your vehicle identification number to look up the original equipment specification.
• Owner’s manual: Some print manuals list power class and battery type; while not always detailed, they confirm that an AGM battery is required.
• Trunk stickers: In some markets, Audi places a battery or power management sticker in the trunk area outlining the spec.

Combining these checks reduces the risk of buying a battery that doesn’t fit properly or doesn’t match the electrical demands of the car.

AGM vs. Conventional Flooded Batteries

The 2011 S4’s design and energy management system expect an AGM battery. Using a conventional flooded battery instead can lead to shorter life and potential electrical issues.

Why AGM Is Recommended

AGM batteries use a glass‑fiber mat to absorb the electrolyte, which makes them spill‑resistant and better able to handle modern vehicles’ heavy electrical use.

Key advantages of AGM for a car like the 2011 Audi S4 include:

• Better deep‑cycle performance: Handles repeated discharging and recharging from high electronic loads.
• Improved vibration resistance: Important in performance‑oriented chassis with stiffer suspension.
• Higher cold‑cranking performance: Delivers strong starting current even in low temperatures.
• Lower self‑discharge: Useful if the car is stored or driven infrequently.
• Electronics‑friendly: Provides more stable voltage for sensitive control modules.

Given these demands, switching from AGM to a cheaper flooded battery is a false economy and can accelerate wear or cause performance quirks.

Key Replacement Considerations

Once you know the correct type and size, there are a few practical factors to consider when replacing the battery in a 2011 S4.

Physical Fit and Mounting

The battery must not only match the correct group size but also fit securely in the S4’s trunk‑mounted tray.

The following factors matter when checking physical compatibility:

• Dimensions: H6/48 batteries typically measure about 10.9″ x 6.9″ x 7.5″ (278 x 175 x 190 mm); they must fit the tray and under the cover.
• Hold‑down: The case must include the lip at the correct height so the factory hold‑down clamp can secure it.
• Terminal orientation: Positive and negative posts must align with the existing cables without stretching or twisting.
• Vent tube connection: Many trunk‑mounted batteries use a vent port; the replacement should either accept the tube or be fully sealed AGM.

A battery that fits loosely or requires forcing cables into place can become a safety hazard and may strain wiring or connections.

Electrical Specs: Ah, CCA, and Reserve Capacity

Even within the correct group size, brands vary slightly in capacity and cranking power.

Consider these electrical specs when choosing among options:

• Amp‑hour rating (Ah): Aim for at least the OEM‑equivalent (around 70–80 Ah) to maintain reserve capacity for electronics.
• Cold Cranking Amps (CCA): A rating in the mid‑ to high‑600s or above helps in cold climates and supports confident starting.
• Reserve capacity (RC): A higher RC figure provides more buffer if accessories run while the engine is off.
• Brand and warranty: Premium lines from Bosch, Varta, Exide, Interstate, and OEM‑branded units usually carry longer warranties and more consistent specs.

Staying near or above the original ratings ensures that the car’s electrical system operates as Audi intended.

Battery Registration and Coding (Important for Modern Audis)

Many modern Audis, including the 2011 S4 on the B8 platform, use a battery management system (BMS) that tracks battery condition and charging. When replacing the battery, Audi recommends registering or coding the new unit.

Why Registration Matters

In simple terms, the car’s computer “learns” the internal resistance and age of the old battery, then tailors charging behavior accordingly.

The following aspects are affected by proper battery registration or coding:

• Charging strategy: The alternator output is regulated based on the battery’s type, age, and condition.
• Battery life: Incorrect assumptions about battery age can overcharge or undercharge the new unit, shortening its lifespan.
• Electrical system stability: A mis‑matched profile can contribute to odd electrical behaviors or warning messages.
• Fault diagnostics: The system logs battery history, aiding in troubleshooting if electrical issues arise later.

While some owners swap batteries without coding and see no immediate problems, following Audi’s procedure is the safer, more professional approach.

How Coding Is Typically Done

Coding or registering the new battery typically requires a scan tool capable of speaking to Audi/VW modules.

Common approaches to completing this step include:

• Dealer service: An Audi dealer can install and code a battery using factory tools.
• Independent shop: Many European‑specialist shops have VCDS, ODIS, or similar capable diagnostics to perform registration.
• DIY with VCDS or OBD apps: Experienced owners sometimes use VCDS (VAG‑COM) or compatible OBD interfaces to update battery information themselves.
• Entering new battery data: The process usually involves inputting brand, capacity (Ah), and a serial or part code in the energy management module.

For a 2011 S4 owner who is not comfortable with diagnostic tools, having a shop handle installation and coding can be worth the cost.

Practical Buying Advice

Once the technical criteria are understood—AGM, H6/Group 48, correct specs—the decision shifts to where and what brand to buy.

Where to Buy a Replacement Battery

Most major retailers and service centers can supply a suitable AGM battery for a 2011 S4.

The following sources are commonly used by owners:

• Audi dealership: Usually the most expensive, but supplies OEM‑spec batteries and can handle coding in one visit.
• European‑specialist garages: Often stock or quickly source the right AGM battery and know how to code it.
• National parts chains: Offer AGM Group 48/H6 options under house brands or big names like Bosch or Exide.
• Online retailers: Provide competitive pricing on exact‑fit AGM units; ensure correct group, polarity, and return policy.

Choosing a retailer that understands the need for AGM and correct fit helps avoid compatibility issues and returns.

Red Flags to Avoid

Not every battery labeled “fits 2011 Audi S4” is an ideal choice, especially from generic sellers.

The following signs may indicate an unsuitable or low‑quality option:

• Non‑AGM chemistry offered as the “standard” choice for your car.
• Lower Ah rating than OEM with little cost savings to justify the trade‑off.
• Unclear or missing CCA and capacity specs on the product page or label.
• Incompatible group size (e.g., 35, 24F, 49) proposed as a universal fit.
• Very short warranties compared to mainstream brands in the same category.

Being selective helps ensure the battery will perform well in a car as electronically complex as the S4.

Summary

The 2011 Audi S4 is designed to use a 12‑volt AGM battery in the H6 (Group 48) size, typically around 70–80 Ah and roughly 680–800 CCA, mounted in the trunk and managed by an electronic battery management system. Owners should confirm exact specs by checking the existing battery label, consulting the owner’s manual or VIN‑based dealer data, and using a reputable fitment guide. When replacing the battery, sticking with AGM technology, ensuring proper physical fit and electrical ratings, and having the new battery registered or coded to the car will provide the best reliability and longevity for both the battery and the vehicle’s sensitive electronics.