2021 GMC Acadia — Battery Size & Group (Specs, CCA, Replacement, Reset)

Quick answer

• BCI group size: H6 (Group 48)
• Cold Cranking Amps (CCA): 730–800 CCA recommended (OEM typically ~760 CCA)
• Reserve capacity (RC): 120–140 minutes (minimum ~120 minutes)
• Battery type: AGM required (Start/Stop–equipped)
• Terminal layout: Top-post, right-hand positive (RHP)
• Physical dimensions: ~11.0 x 6.94 x 7.5 in (278 x 175 x 190 mm)
• Dual-battery setup (diesel): Not applicable — 2021 Acadia uses a single 12V battery (gasoline only)

Replacement battery options

• ACDelco Gold 48AGM (AGM, direct-fit H6/48)
• Interstate MTX-48/H6 (AGM, Start/Stop rated)
• DieHard Platinum AGM — size 48/H6 (AGM)
• Optima YellowTop DH6 (AGM)
• Odyssey Performance Series 48/H6 AGM

Note: AGM part numbers above are provided only where commonly published by the manufacturer. If shopping online, filter by “Group 48/H6 AGM” for best fit.

AGM vs flooded — which does this vehicle need?

The 2021 GMC Acadia is equipped with automatic Start/Stop, which places higher cycling demands on the battery. GM specifies an AGM (Absorbent Glass Mat) battery for this application. AGM batteries are designed for frequent charge/discharge cycles, deliver higher cranking performance in cold weather, and better tolerate heat and vibration than conventional flooded batteries.

• Do not downgrade to a flooded battery. Using a non‑AGM unit can lead to poor Start/Stop performance, premature battery failure, and charging system faults.
• EFB (enhanced flooded) options may appear in some catalogs, but AGM remains the preferred specification for the Acadia’s duty cycle.

Post-installation relearn / reset procedure

You don’t need to “code” or register a new battery on the Acadia, but a few resets help restore normal operation after power loss:

1. Installation basics

• Preserve memory with a 12V memory saver if available.
• Connect positive cable first, then negative. Ensure the battery sensor on the negative terminal is seated correctly.

2. Idle/charging relearn

• Start the engine and let it idle in Park for about 3 minutes with all accessories off.
• Turn the engine off for 60 seconds.
• Restart and idle another 3 minutes, then drive normally (mix of city/highway) for 10–20 minutes. The battery monitoring system will relearn state of charge over the next few drive cycles.

3. Power window express-up/down relearn (each door)

• Key ON/engine running. Fully close the window and hold the switch UP for 2 seconds.
• Fully lower the window and hold the switch DOWN for 2 seconds. Repeat once if needed.

4. Sunroof (if equipped)

• Close the panel completely, then hold the close switch for ~2 seconds to sync the limit.

5. HVAC actuator recalibration

• Key ON (engine running or not), set HVAC to OFF and don’t touch any controls for ~60 seconds. Clicking behind the dash during this period can be normal.

6. Steering angle/traction aids

• After startup, turn the steering wheel lock-to-lock once, then center it. Any stability/traction messages should clear after a short drive.

7. Radio/clock/driver presets

• Re-enter the clock and radio presets. Bluetooth pairings are typically retained but verify.

Signs of a failing battery

• Slow or hesitant cranking, especially after short trips
• “Auto Stop/Start Unavailable” or “Battery Saver Active” messages
• Dim headlights or unstable idle with accessories on
• Frequent jump-starts or the need to charge after sitting a few days
• Corroded or swollen case, or sulfur/rotten-egg odor after driving

If you see multiple symptoms, test the battery with a conductance tester and check for parasitic draw before replacing.

Common battery issues for this generation

• Start/Stop cycling and short-trip use accelerate wear: AGMs handle it better, but repeated short drives may never fully recharge the battery. A smart charger maintenance charge a few times per year can extend life.
• Downgrading to a flooded battery: Often leads to poor Start/Stop function and early failure. Stick with AGM.
• Loose or corroded connections: Clean and tighten the battery posts and the chassis/engine grounds. Pay attention to the negative battery current sensor ring.
• Parasitic draws: Infotainment modules, liftgate control modules, or accessories left in the power outlets can keep the network awake. Verify key-off current draw is within spec after a 30–45 minute sleep period.
• Heat exposure: Under-hood heat shortens battery life. Ensure the battery cover/insulator (if equipped) is installed correctly.

Use a direct-fit Group 48/H6 AGM with at least ~730 CCA and ~120 minutes RC for reliable year-round performance.

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