Mercedes-Benz Auxiliary Battery – 12V 12Ah AGM

Specification Overview

Genuine Mercedes-Benz auxiliary (secondary) battery. This is a Valve Regulated Lead-Acid (VRLA) battery utilizing Absorbent Glass Mat (AGM) technology. It is factory-spec for numerous Mercedes-Benz models equipped with dual-battery systems, supporting advanced electrical features independent of the starter battery.

• Type: VRLA / AGM (Sealed, Maintenance-Free)

• Voltage: 12V

• Capacity: 12Ah (Amp-hours)

• Cold Cranking Amps (CCA/EN): 200A

• Terminal Type: Stud terminals

• Case Type: C56

• Weight (Filled): Approx. 4.6 kg

• Made in: China (by Fabit for Mercedes-Benz)

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Application & Engine Fitment

This auxiliary battery serves as a secondary power source for convenience functions like the Start/Stop system, the “HOLD” function, the Electronic Stability Program (ESP), the ECUs, and the alarm system.

It is a direct replacement for several older part numbers: A0019822708, A0009829308, A2115410001, and A0019827008.

Comprehensive Model Fitment (Partial List):

⚠️ Important: This is the secondary (auxiliary) battery, not the main starter battery. It is often smaller and located in the engine bay, under the dashboard, or in the seat base. Always verify the exact part number by VIN (17-digit chassis number) before ordering.

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Service Life & Change Intervals (Technical Data)

The auxiliary battery has a lifespan similar to the main starter battery.

Standard Expected Lifespan:

• 4 to 6 years under normal conditions.

• Some can last up to 7 years depending on usage.

Critical Adjustment for Kampala (Severe Operating Conditions):
The operational climate in Kampala (ambient temperatures 20°C–40°C), high humidity, and frequent stop-and-go traffic create a “Severe Duty” environment for all batteries. High ambient temperatures significantly accelerate the chemical degradation of the battery.

Recommended Replacement Interval under East African operating parameters:

• 3 to 5 years maximum.

• If the vehicle is used primarily for short trips in the city, we recommend inspection starting from 3 years to prevent unexpected failure of the Start/Stop and HOLD functions.

Failure Symptoms – When to Replace:

• “Auxiliary Battery Malfunction” warning on the instrument cluster.

• Start/Stop system not functioning.

• “HOLD” function unavailable.

• Intermittent electrical issues with the ECUs or alarm system.

⚠️ Important: A failing auxiliary battery can cause a cascade of electrical errors. Replacing it promptly resolves many of these “phantom” electrical malfunctions.

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Packaging & Pricing (Alps Autoz Kampala)

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Technical Notes for the Workshop

• Installation: The replacement procedure can be more complex than changing a main battery. The auxiliary battery is often located in hard-to-reach places (e.g., under the driver’s seat, behind the dashboard). Consult the vehicle-specific service manual.

• Registration: In most models, the auxiliary battery does not require “coding” or “registration” with the vehicle’s computer system, unlike the main starter battery.

• Genuine vs. Aftermarket: Equivalent aftermarket brands with the correct specifications (12V, 12Ah, AGM) include:

  • VARTA YTX14-BS (12V 12Ah 200A)

  • BANNER, AMARON, YUASA

• HazMat: This part contains hazardous materials (acid) and requires special handling for shipping.

• Compatibility Note: This battery is for dual-battery system vehicles. It is not a replacement for the main starter battery in single-battery systems.

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Alps Autoz – Kampala