2020 Subaru Outback Battery: Group Size & Replacement Guide

A dead battery in your 2020 Subaru Outback can bring your adventure to a halt. Knowing the correct battery size, type, and replacement procedure is crucial for keeping its advanced safety systems and robust electronics functioning properly. This guide covers everything you need to know, from the essential specs to the reset procedure required after installation.

Quick answer: 2020 Subaru Outback Battery Specs

For all trims of the 2020 Subaru Outback, including the Base, Premium, Limited, Touring, Onyx Edition XT, Limited XT, and Touring XT, you will need an AGM battery. The specifications are as follows:

• BCI Group Size: Group 47 (also listed as H5, L2, or EN344).
• Battery Type: AGM (Absorbent Glass Mat) is required.
• Cold Cranking Amps (CCA): The original battery is rated for around 550 CCA, but aftermarket replacements often offer 600-680 CCA for better performance in cold climates.
• Terminal Layout: Top Post, Right-Hand Positive.
• Reserve Capacity (RC): A minimum of 100 minutes is recommended.
• Approximate Dimensions: 9.7" L x 6.9" W x 7.5" H (246mm x 175mm x 190mm).

Replacement Battery Options

Choosing a high-quality AGM battery is essential for the longevity and performance of your Outback's electrical system. Here are several popular and reliable replacement options that are a direct fit for the 2020 Outback.

• Interstate MTX-47/H5: A highly-regarded AGM battery known for its long life and reliable starting power.
• DieHard Platinum AGM H5-AGM: A premium option available from Advance Auto Parts, offering excellent CCA ratings and a robust warranty.
• ACDelco Gold 47AGM: A trusted OEM supplier for many brands, this battery provides a dependable, factory-quality fit and performance.
• Odyssey ODP-AGM47 H5 L2: Often considered a top-tier performance battery, Odyssey batteries are known for their extreme temperature tolerance and deep-cycling capabilities.

Note: While a popular brand, Optima Batteries does not currently offer a direct-fit Group 47 battery for the 2020 Subaru Outback.

AGM vs Flooded — Which Does This Vehicle Need?

The 2020 Subaru Outback absolutely requires an AGM battery. Do not install a conventional flooded (lead-acid) battery.

This requirement is due to two key factors: the vehicle's Auto Start-Stop system and its high electrical demands. The Auto Start-Stop feature, which shuts the engine off at a standstill to save fuel, puts immense strain on the battery. AGM batteries are designed for this frequent, high-load cycling. Furthermore, the extensive electronics—from the large STARLINK infotainment screen to the EyeSight Driver Assist Technology—require a stable and consistent voltage that only an AGM battery can reliably provide. Installing a flooded battery will lead to premature failure, potential damage to the vehicle's charging system, and malfunctioning onboard electronics.

Post-Installation Relearn / Reset Procedure

After replacing the battery in your 2020 Outback, you must perform a simple relearn procedure to ensure the Engine Control Unit (ECU) and other modules operate correctly.

1. ECU Idle Relearn: After connecting the new battery, start the engine and allow it to idle in Park for at least 5 to 10 minutes. Do not press the accelerator or turn on accessories like the A/C. This allows the ECU to relearn the engine's base idle parameters.
2. Power Window Reset: The battery disconnect will erase the memory for the "auto-up" and "auto-down" power window functions. To reset them, go to each window switch and perform the following:
   • Push the switch down to fully open the window, and hold the switch for an extra second after it is fully open.
   • Pull the switch up to fully close the window, and hold the switch for an extra second after it is fully closed.

This simple procedure will restore all normal functions.

Signs of a Failing Battery

• Slow Engine Crank: The engine turns over sluggishly, especially on cold mornings.
• Dimming Lights: Headlights or interior lights dim when the engine is starting or when the Auto Start-Stop system engages.
• Warning Lights: A battery or charging system warning light appears on the dash.
• Frequent Start-Stop Deactivation: You may see a message that the Auto Start-Stop system is unavailable. This is often an early sign that the battery can no longer support the feature.
• Swollen Battery Case: If the sides of the battery are bulging, it is failing internally and should be replaced immediately.

Common Battery Issues for This Generation

The sixth-generation Subaru Outback (2020-present) has been the subject of numerous owner complaints regarding premature battery failure and parasitic drain. Some owners have experienced dead batteries in as little as a few weeks or months. The issue is often linked to onboard electronics, particularly the Data Communication Module (DCM) that powers the MySubaru telematics, failing to enter "sleep mode" after the vehicle is shut off. This creates a slow, persistent drain that can deplete a healthy battery over a few days. While Subaru has issued software updates to address this, some owners still report issues. If you experience a repeatedly dead battery, it is critical to have a technician perform a parasitic draw test to diagnose the root cause.

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