What Kind of Battery Does a BMW 328i Take?

A BMW 328i typically uses an AGM (Absorbent Glass Mat) 12‑volt battery with specific size and power ratings that vary slightly by model year and market, most commonly in the H6/LN3 or H7/LN4 size group, and it must be correctly registered or coded to the car’s computer after replacement.

Understanding the BMW 328i and Its Battery Requirements

The BMW 328i, spanning multiple generations from the E36 and E46 to the more recent E90/E91/E92/E93 and F30 models, is designed with an advanced electrical system that places stricter demands on the battery than many non-luxury cars. While earlier generations used conventional flooded lead‑acid batteries, most late‑2000s and newer 328i models are engineered for AGM batteries, which better handle high electrical loads and start‑stop or energy management systems.

Main Battery Types by Generation

BMW 328i models use a 12‑volt battery located in the trunk (right/rear side area in most models). The exact type is determined by the model generation, engine options, and regional equipment. The key distinctions are between older models that can work with standard flooded batteries and newer models that require AGM batteries and coding.

E36 & E46 328i (1990s–mid‑2000s)

For the older E36 (where available as 328i) and E46 328i models, the electrical system is simpler, and batteries do not require software registration. These cars typically use large 12‑volt flooded lead‑acid batteries but may also accept AGM replacements that meet or exceed the original specifications.

The following list outlines the common battery specifications for E36/E46‑era 328i models and what owners should look for when shopping.

• Battery type: Conventional flooded lead‑acid (AGM optional as an upgrade)
• Group size (North America): Group 91, 92, 93 or equivalent European size (often similar to H6/LN3‑type footprint, depending on brand catalog)
• Voltage: 12 V
• Cold Cranking Amps (CCA): Typically in the 650–800 CCA range
• Reserve capacity / Ah rating: Commonly around 70–80 Ah (varies by brand)
• Registration requirement: Not required; the car does not need coding after replacement

For these earlier 328i models, the priority is physical fit, sufficient CCA, and quality; there is more flexibility in battery chemistry as long as specifications match or exceed what BMW originally supplied.

E90/E91/E92/E93 328i (Approx. 2006–2013)

The E9x generation 328i, widely sold in North America and Europe, marked a shift to more sophisticated power management. Many of these cars, especially those with more options or cold‑weather packages, came with AGM batteries from the factory. Even when not originally AGM, modern replacements are often AGM due to their durability and compatibility with BMW’s Intelligent Battery Sensor (IBS).

The list below summarizes the key battery parameters for most E90‑series 328i models.

• Battery type: AGM strongly recommended; some base cars originally had flooded batteries, but like‑for‑like or AGM replacement is standard practice now
• Typical size groups:
  

  • H6 / LN3 / Group 48: Common for many 328i trims
  • H7 / LN4 / Group 94R: Used in higher‑load configurations or cold‑weather markets

• Voltage: 12 V
• Amp‑hour rating (Ah): Roughly 70–90 Ah depending on size and equipment level
• Cold Cranking Amps (CCA): Typically 720–850 CCA or higher for H7 units
• Location: Trunk, usually on the right side under a trim panel
• Registration required: Yes, the new battery must be registered in the car’s diagnostic system

For E90‑series 328i models, choosing the correct physical size and chemistry is only part of the job; registering the new battery ensures the charging system uses the correct profile and prolongs battery life.

F30 328i (Approx. 2012–2018)

The F30‑generation 328i (including 328i xDrive) relies even more heavily on an intelligent charging strategy, regenerative braking (on many models), and extensive onboard electronics. These cars are built around AGM batteries as the norm, and software registration or coding is mandatory after replacement.

The next list lays out the typical battery specs for most F30 328i models currently on the road.

• Battery type: AGM 12‑volt only (as per BMW’s standard spec for most F30 328i)
• Typical size groups:
  

  • H6 / LN3 / Group 48 AGM: Common on many 328i sedans
  • H7 / LN4 / Group 94R AGM: Used when more capacity is needed or in certain markets

• Amp‑hour rating (Ah): Commonly 80–90 Ah
• CCA rating: Often 760–900 CCA depending on brand and size
• Location: Trunk, under the floor or right‑side compartment
• Registration/coding: Required; the battery type (AGM vs flooded), capacity (Ah), and sometimes size must be properly set via diagnostic software

Owners of F30 328i models should treat the battery not as a simple wear item but as part of an integrated energy management system where matching the correct AGM spec and performing proper registration is essential.

Why AGM Batteries Are Favored in Modern BMW 328i Models

AGM batteries are now the default in most modern German cars, including the BMW 328i, especially from the late E90 generation onward. They are designed to cope with high electrical loads, repeated starts, and energy recovery systems without suffering the same level of degradation as traditional flooded cells.

The following list explains the advantages of AGM batteries in the context of BMW 328i usage.

• Deeper discharge tolerance: AGMs handle partial state‑of‑charge and frequent discharge/charge cycles better than many flooded batteries.
• Higher vibration resistance: The glass mat construction is more robust under trunk or chassis vibrations.
• Lower risk of acid leaks: Sealed design minimizes spillage, important in interior/trunk mounting.
• Improved cold‑weather performance: Generally offers better cranking in low temperatures.
• Compatibility with IBS and smart charging: Designed to work with BMW’s Intelligent Battery Sensor and variable charging strategies.

These features make AGM batteries well‑suited to the demands of a modern 328i, where comfort electronics, safety systems, and sometimes start‑stop technology place persistent demands on the 12‑volt system.

Battery Registration and Coding: Why It Matters

On E90 and F30 328i models, simply dropping in a new battery without telling the car’s computer can shorten the battery’s life and trigger charging irregularities. BMW’s Intelligent Battery Sensor measures current, voltage, and temperature and adapts charging based on the age and type of the installed battery.

The list below describes what happens during the registration/coding process and why it is important.

• Resets battery age data: The system treats the battery as new, adjusting the charge curves appropriately.
• Applies correct charging profile: The software uses distinct profiles for AGM vs flooded and for different capacity ratings (e.g., 70 Ah vs 90 Ah).
• Prevents overcharging or undercharging: Mismatched profiles can overwork a new battery or leave it undercharged.
• Maintains accurate energy diagnostics: Ensures that IBS readings and energy management decisions (like shutting down accessories) are correct.
• Reduces fault codes: Proper registration helps avoid spurious electrical or battery‑related warnings.

Because of these factors, most independent BMW specialists and dealerships insist on registering and, if needed, coding the new battery whenever the type or capacity changes.

How to Choose the Right Replacement Battery

To pick the correct battery for a BMW 328i, the owner needs to consider model year, battery chemistry, size, and electrical demands. Buying only “by look” or “by price” can lead to fitment or electronic issues, especially on post‑2006 cars.

The following list outlines the key steps and checks for selecting a compatible battery.

1. Identify the model year and chassis: Determine whether the vehicle is E46, E90, or F30 (or similar regional variants).
2. Check the current battery label: Look for information on chemistry (AGM vs flooded), Ah rating, and CCA.
3. Match or exceed capacity: Choose a battery with equal or higher Ah and CCA, within the size specified for the model.
4. Confirm physical size group: Use catalog look‑ups or the existing battery’s markings (e.g., H6/LN3, H7/LN4, Group 48, 94R).
5. Prefer AGM for E90/F30: Use AGM batteries where originally equipped and whenever the car has IBS and advanced power management.
6. Plan for registration/coding: Arrange for a dealer or BMW‑capable independent shop to register the battery, or use appropriate software and interface if doing it yourself.
7. Verify venting provisions: Use the correct vent tube connection required for trunk‑mounted batteries.

Following these steps significantly reduces the risk of compatibility problems and ensures the vehicle’s charging system and electronics operate as designed after the new battery is installed.

Common Battery Sizes and Labels You’ll See for a 328i

Battery size nomenclature can be confusing, with different standards used in North America and Europe. Many BMW 328i owners encounter “H6,” “H7,” “LN3,” “LN4,” “Group 48,” or “Group 94R” when shopping, all of which describe dimensions and terminal layouts rather than chemistry alone.

The next list summarizes the most common groups applicable to a modern 328i.

• H6 / LN3 / Group 48: Mid‑size battery frequently used in E90 and F30 328i; good balance of capacity and weight.
• H7 / LN4 / Group 94R: Slightly larger and often higher‑capacity; used where more reserve capacity or cold‑cranking performance is desired.
• Group 91/92/93 (older models): Used by many E36/E46 3‑Series in certain markets; similar footprint but older naming convention.
• Ah labels (e.g., 70 Ah, 80 Ah, 90 Ah): Specify energy capacity and must match what’s coded into newer BMWs.
• AGM vs “wet” (flooded): Often marked clearly on the case; “AGM” or “VRLA” means it is a sealed Absorbent Glass Mat design.

Understanding these labels helps ensure you choose a battery that not only fits physically but is recognized correctly by both parts catalogs and BMW diagnostic systems.

Practical Tips Before Replacing a BMW 328i Battery

Battery replacement on a 328i is straightforward physically but requires a bit of preparation, especially on vehicles with IBS and coded charging. A little planning can prevent electrical glitches and save time.

The following list gathers pragmatic tips to keep in mind before and during replacement.

• Back up settings: Be prepared to re‑enter radio presets, clock, and sometimes one‑touch window initialization.
• Use a memory saver (optional): Some owners use backup power to preserve modules’ settings, though this is not strictly required.
• Disconnect negative terminal first: This reduces the risk of short‑circuits during removal.
• Handle the IBS carefully: On IBS‑equipped cars, the sensor is integrated into the negative cable; do not pry or pull on it.
• Secure the new battery firmly: Always use the factory hold‑down clamps to prevent movement.
• Connect vent hose: Ensure the vent tube is properly attached to the battery’s vent port.
• Register the battery promptly: Complete the software registration/coding step immediately after installation.

These steps help protect sensitive electronics and ensure the new battery delivers reliable service without triggering unnecessary warning lights or premature wear.

Summary

A BMW 328i uses a 12‑volt trunk‑mounted battery whose exact specification depends on the generation, but most modern models—from the late E90 through the F30—are designed for AGM units in sizes such as H6/LN3 (Group 48) or H7/LN4 (Group 94R). Earlier E36/E46 328i models can function with high‑quality flooded lead‑acid batteries, while newer cars require AGM and must have the replacement battery registered or coded to the vehicle’s computer to ensure correct charging behavior. Matching the proper size group, chemistry, amp‑hour rating, and then performing registration is essential for long battery life and trouble‑free operation in any BMW 328i.