Replacement Battery for 2002-2005 BMW 745Li

Marathon 9AGM49 Group 49 (H8) AGM Battery: Premium Power, Unbeatable Value

Don't overpay for Deka, Duracell, or Autocraft. The Marathon 9AGM49 Group 49 (H8) is your perfect replacement solution. It's engineered to meet or exceed the demands of today's modern European and domestic vehicles and delivers high-performance starting power with the longevity you need, all at a superior value.

Why Choose the Marathon 9AGM49 Over Competitors?

• Superior Cranking Power: We beat the competition where it counts. Many batteries test at 850 Cold Crank Amps (CCA). Our Marathon battery offers 900 CCA.
• Greater Reserve Capacity: The Marathon 9AGM49 provides an 180-minute Reserve Capacity (RC), giving you more peace of mind and more time to run accessories (like navigation or charging) when the engine is off, compared to the standard 170 RC.
• Exceptional Value: As a direct-sourced, private-label brand, we cut out the national brand advertising costs. You receive a premium, maintenance-free AGM battery made by a leading global manufacturer for significantly less.

Advanced AGM Technology Explained

Our Marathon batteries are Absorbent Glass Mat (AGM) batteries. This is a critical upgrade for vehicles with start/stop technology and complex electronics. The advanced, sealed design features a special fiberglass mat that locks the electrolyte in place, providing several key advantages:

• True Maintenance-Free: Eliminates acid spills and water refills.
• Extreme Durability: Resistant to vibration and road vibration. Leads to a longer, more reliable service life.
• Faster Recharge: Recovers quickly from deep discharge cycles, maintaining performance season after season.

⚠️ Attention BMW, Audi, and Mercedes-Benz Owners: Register Your Battery!

The Group 49 (H8) size is common in European vehicles. While the Marathon 9AGM49 is an exact physical fit, your car's sophisticated Battery Management System (BMS) must be informed that a new battery has been installed. This process, Battery Registration, will tell your alternator the battery has been changed.

If you do not register the new battery, the alternator will treat your new battery as degraded (i.e. like your old battery). This can shorten it's life significantly. Please consult your owner's manual or a certified mechanic if you need help with the registration process.

Product Specifications at a Glance

This battery is designed for a seamless, hassle-free replacement:

• BCI Group Size 49 (H8)
• Voltage 12 Volt
• CCA 900 Cold Cranking Amps
• Capacity 92 Ah
• Reserve Capacity 180 Minutes
• Warranty 2 Year Full Replacement
• Dimensions 13.94" (L) x 6.88" (W) x 7.5" (H)

A: The Marathon 9AGM49 is a high-performance Group 49 (H8) Absorbent Glass Mat (AGM) battery. It is a popular fit for many European and domestic vehicles, including models from BMW (3-Series, 5-Series), Mercedes-Benz (C-Class, E-Class), and Audi. The Group 49 size is a standard in the industry, which is why it fits a wide range of vehicles that require a reliable power source. You can use our vehicle finder to confirm the exact fit for your car..

A: AGM stands for Absorbent Glass Mat. In an AGM battery, the electrolyte (acid) is held in a fiberglass mat rather than free-flowing. This design makes the battery completely sealed and spill-proof. AGM batteries are ideal for modern vehicles with start-stop systems, sophisticated electronics, or luxury features because they offer higher power output, faster charging, and superior vibration resistance. They also tend to last longer than traditional flooded batteries..

A: For many modern vehicles, especially BMW, Mercedes-Benz, and Audi models, the answer is yes. The car's computer has a Battery Management System (BMS) that is programmed for the original battery's age and health. When you install a new Marathon 9AGM49 battery, you should register it with the car's computer. This tells the system to reset its charging profile, which ensures the new battery charges correctly and lasts for its full lifespan.

A: A high-quality Group 49 AGM battery like the Marathon 9AGM49 can last between 3 to 5 years or even longer. The exact lifespan depends on several factors, including your driving habits, climate, and how many electronic accessories your vehicle uses. Consistent short trips and extreme temperatures can reduce a battery's life, but the robust design of AGM batteries helps them withstand these conditions better than standard batteries.

A: The easiest way is to use the vehicle filter on this page. Simply select your car's make, model, and year, and we will tell you if the Marathon 9AGM49 is a confirmed fit. You can also check your car's owner's manual or look at the battery currently installed in your vehicle to verify the size and type required.