What Battery Goes in a 2007 BMW 328i?

The 2007 BMW 328i typically uses a Group 94R (H7) battery, absorbed glass mat (AGM) or flooded lead-acid, with around 80–90 Ah capacity and 720–900 CCA, but the exact choice depends on options (e.g., iDrive, cold-weather package) and you must register the new battery in the car’s computer after installation. This article explains the correct specifications, compatible options, and what to watch out for when replacing the battery on a 2007 BMW 328i.

Understanding the 2007 BMW 328i Battery Requirements

The E90-generation 2007 BMW 328i uses a “smart” charging system that expects very specific battery characteristics. Choosing a random battery that only “physically fits” can shorten battery life, trigger warning lights, or strain the alternator. Knowing the proper group size, type, and electrical specs is essential before you buy.

Battery Group Size and Physical Fit

The most important physical specification is the battery’s group size, which ensures it fits securely in the trunk compartment and that the terminals line up correctly. For the 2007 BMW 328i, BMW and major aftermarket catalogs align on a common standard.

The following list describes the common group sizes that can fit a 2007 BMW 328i, and what they mean for compatibility and ease of installation.

• Primary recommended size: Group 94R (H7) – This is the standard size used in most 2007 BMW 328i models. The “R” means reversed terminals, matching BMW’s trunk layout.
• Alternative size sometimes used: Group 49 (H8) – Slightly larger in some dimensions; can fit certain E90 battery trays but may be too tight or require tray adjustment and is not the factory default for most 328i trims.
• European codes: H7 / L4 for 94R, H8 / L5 for 49 – Sometimes batteries are labeled by these Euro codes instead of BCI “Group” numbers.
• Key dimensions for 94R/H7 – Roughly 12.4 in (315 mm) length, 6.9 in (175 mm) width, 7.5 in (190 mm) height, with reversed (R) terminals.

In practical terms, Group 94R/H7 remains the safest, most straightforward choice for a 2007 BMW 328i, matching OEM dimensions, clamp positions, and cable reach without modifications.

AGM vs. Flooded Lead-Acid: Which Type Is Correct?

BMW offered both conventional flooded lead-acid and AGM (absorbed glass mat) batteries in this era, depending on equipment and market. Many 2007 328i models—especially those with more electrical options—either came with AGM or strongly benefit from it.

The next list explains the differences between AGM and flooded batteries and how to decide which type suits your 2007 328i.

• AGM battery – More resistant to deep discharges, better performance in high electrical-load cars (iDrive, upgraded audio, heated seats, etc.), and generally preferred for BMW’s modern charging systems. Usually labeled “AGM,” “VRLA,” or “Absorbent Glass Mat.”
• Flooded lead-acid battery – Traditional design; often cheaper and still widely used. Many base 328i cars originally shipped with this type, especially without heavy-option packages.
• Matching original type is best – If the car came with AGM, replace with AGM. If it came with flooded, you can stay with flooded or upgrade to AGM, but changing type should be reflected in the battery registration coding.
• AGM pros for older BMWs – Handles frequent short trips, city driving, and high accessory use better, which is common for E90 owners today, making AGM a popular replacement choice.

Choosing the right type isn’t just about price; it affects battery life and how well the charging system manages voltage and current over time, making AGM a smart long-term investment for many 328i owners.

Key Electrical Specifications for a 2007 BMW 328i Battery

Beyond physical size, the electrical ratings of the battery must be in the correct range to support the BMW’s electronics and to match what the engine control and charging systems expect. Overshooting or undershooting these values can affect reliability and how the alternator charges the battery.

Capacity (Ah), Cold Cranking Amps (CCA), and Reserve Capacity

Automakers specify multiple performance figures. For the 2007 328i, capacity (Ah) and cold cranking amps (CCA) are the most critical, alongside reserve capacity, which is often implied in the battery’s overall rating.

The list below outlines the typical target values you should look for when buying a replacement battery for a 2007 BMW 328i.

• Capacity (Ah) – Common OEM range is about 70–90 Ah. Many factory and quality replacement batteries fall around 80–90 Ah for 94R/H7 in this car.
• Cold Cranking Amps (CCA) – Look for roughly 720–900 CCA, depending on brand and whether it’s AGM. Higher CCA is typically beneficial for cold climates.
• Reserve Capacity (RC) – Often in the range of 140–160 minutes for a strong 94R/H7 battery, meaning the battery can power a moderate load for a sustained period if the alternator fails.
• Voltage – Standard automotive 12 V (nominal), usually around 12.6–12.8 V fully charged for AGM batteries when the engine is off.

Staying close to the original Ah and CCA specifications helps ensure the car starts reliably in all seasons and that the alternator and charging logic don’t overwork or undercharge the new battery.

Polarity and Venting

Because the battery sits in the trunk, proper polarity and venting aren’t optional; they are safety and functionality requirements. Incorrect terminal layout or missing venting can cause cable strain, corrosion, or even dangerous gas buildup.

The following list highlights the polarity and venting considerations that owners should check before finalizing a purchase.

• Polarity: “R” (reversed) layout – Group 94R means the positive and negative posts are reversed compared with a standard 94. Using a battery without the “R” can make the cables not reach or force unsafe routing.
• Trunk location requires venting – The battery must have a vent port that connects to BMW’s plastic vent tube so any gases are directed outside the car.
• AGM still needs venting – While AGM batteries vent less under normal conditions, the vent tube still must be connected for safety in overcharge or failure scenarios.
• Terminal style – Standard top-post automotive terminals; avoid batteries with side-post-only designs or non-standard terminals, which won’t match BMW clamps.

Confirming polarity and vent compatibility before purchase prevents installation headaches and ensures that the 328i’s trunk-mounted battery remains both safe and serviceable.

Typical OEM and Aftermarket Battery Options

Owners of a 2007 BMW 328i can choose between original BMW-branded batteries and high-quality aftermarket units from U.S. and global manufacturers. Many modern aftermarket offerings match or exceed BMW’s original specifications when selected correctly.

Factory-Style and Premium Replacement Brands

While exact part numbers may vary by region and year, certain BMW and aftermarket brands are regularly recommended by mechanics and parts catalogs for the E90 328i.

The list below introduces common, reputable options drivers often use when replacing the battery in a 2007 BMW 328i.

• BMW OEM battery – Sold at BMW dealers, often labeled as 90 Ah AGM or similar; designed to match factory specs and easily coded/registered via dealer tools.
• Exide / VARTA (Europe) – Frequently used as OEM suppliers; look for a 94R/H7 AGM or equivalent with 80–90 Ah and CCA in the 720–900 range.
• Interstate (North America) – Models like the MTX-94R/H7 (AGM) or MTP-94R/H7 (flooded) are commonly listed as fits for 2007 328i.
• AGM-focused brands – Options from Odyssey, NorthStar (now part of Enersys), or high-end lines from local chains (e.g., AutoZone Duralast Platinum AGM 94R-DLG, Advance Auto DieHard AGM 94R) are popular upgrades.
• Budget but compatible choices – Many big-box store house brands offer 94R/H7 batteries; verify that they meet the necessary Ah and CCA specs and include a vent port.

Choosing a reputable brand with verified compatibility is more important than the logo on the label, especially if the battery meets the 94R/H7 format, correct capacity, and is properly registered in the car.

Battery Registration: A Critical Step After Replacement

Unlike many older cars, the 2007 BMW 328i isn’t fully “plug-and-play” when it comes to batteries. After installing a new battery, you are supposed to “register” it with the vehicle’s computer so the charging system adapts to the new battery’s condition and specifications.

Why Registration Matters on a 2007 328i

Battery registration updates the car’s Intelligent Battery Sensor (IBS) and associated control modules with the details of the new battery. Skipping this step can lead to overcharging, undercharging, or puzzling electrical issues over time.

The following list outlines why and how battery registration should be handled for your 2007 BMW 328i.

• Adjusts charging strategy – The system tailors voltage and current based on battery age and type; without reset, it assumes the battery is still old and may overcharge a new one.
• Prevents premature battery wear – An unregistered new battery may fail earlier due to incorrect charge cycles managed by outdated data in the control module.
• Required if changing Ah or type (AGM vs flooded) – If you move from 70 Ah to 90 Ah, or flooded to AGM, the coding must be updated to reflect the new configuration.
• How to register – Can be done at a BMW dealer, by an independent BMW specialist, or with owner tools such as BMW-specific OBD software (e.g., ISTA, INPA) or certain aftermarket scan tools that support E90 battery registration.

Confirming that battery registration has been completed—either by a shop or via your own diagnostic tool—is as important as picking the right battery, especially for long-term reliability.

Installation and Owner Considerations

Replacing the battery on a 2007 BMW 328i is within reach for a capable DIY owner, but it is not identical to a simple under-hood swap. The trunk location, IBS sensor, and registration requirements mean you should plan the job carefully.

Basic Installation Points to Keep in Mind

Although full step-by-step instructions vary by toolset and experience, several universal points apply to nearly every E90 battery replacement.

The list below summarizes common practical tips and precautions for swapping the battery in a 2007 BMW 328i.

• Locate the battery in the right rear of the trunk – Under the trim panel; you will see the battery secured in a tray with a hold-down clamp.
• Disconnect negative terminal first – To avoid short circuits; reconnect it last after the positive terminal and IBS connections are secure.
• Handle the IBS connection carefully – The Intelligent Battery Sensor is mounted near the negative terminal; do not bypass or damage it.
• Secure the hold-down clamp and bracket – The large 94R battery must be firmly clamped to prevent movement, especially in a rear-mounted position.
• Reconnect the vent tube – Ensure the plastic vent hose is firmly attached to the new battery’s vent port to route gases outside the cabin.
• Perform battery registration – As soon as possible after installation, ideally before extensive driving.

Taking your time with these steps and using the correct tools helps ensure a safe replacement process and avoids issues such as loose batteries, charging faults, or recurring warning messages.

Summary

A 2007 BMW 328i typically uses a Group 94R (H7) battery, either AGM or conventional flooded, with a capacity around 80–90 Ah and roughly 720–900 CCA. The battery is trunk-mounted and must support proper venting and reversed terminal layout. While BMW’s own battery is a safe choice, many high-quality aftermarket 94R/H7 batteries fit and perform well when they match these specs.

Crucially, any new battery must be properly registered in the car’s computer so the intelligent charging system can adapt to the fresh battery’s type and capacity. With the correct group size, chemistry, electrical ratings, and post-installation registration, the 2007 328i’s electrical system will remain reliable and the new battery is likely to deliver a full service life.