2020 GMC Sierra 2500HD Battery Size & Group

Quick answer

• BCI Group Size (Diesel): Group 31 (dual battery setup)
• BCI Group Size (Gasoline): Group 48/H6 or Group 94R/H7 (varies by trim and options)
• CCA Rating (Diesel): 800-900 CCA per battery (minimum)
• CCA Rating (Gasoline): 730-800 CCA (minimum)
• Reserve Capacity (Diesel): 160-180 minutes per battery (minimum)
• Reserve Capacity (Gasoline): 120-140 minutes (minimum)
• AGM vs. Flooded: Either is acceptable, but AGM is highly recommended for its durability and performance, especially in heavy-duty applications. Some models may have come with an AGM from the factory.
• Terminal Layout: Top post (SAEJIS posts)
• Physical Dimensions (Group 31): Approximately 13" L x 6.8" W x 9.4" H
• Physical Dimensions (Group 48/H6): Approximately 11" L x 6.9" W x 7.6" H
• Physical Dimensions (Group 94R/H7): Approximately 12.4" L x 6.9" W x 7.6" H
• Dual-Battery Setup: Yes, diesel models utilize a dual-battery setup (two Group 31 batteries).

Replacement battery options

When it's time to replace the battery in your 2020 GMC Sierra 2500HD, you have several excellent options from reputable brands. Always double-check the BCI group size and CCA ratings against your vehicle's specific requirements, especially if you have a gas vs. diesel or different trim levels.

• Interstate:
  • Diesel (Group 31): Interstate MTZ-31 (AGM) or M-31 (Flooded)
  • Gasoline (Group 48/H6): Interstate MTZ-48/H6 (AGM) or MTP-48/H6 (Flooded)
  • Gasoline (Group 94R/H7): Interstate MTZ-94R/H7 (AGM) or MTP-94R/H7 (Flooded)
• Optima:
  • Diesel (Group 31): Optima YellowTop D31A (AGM, deep cycle/starting)
  • Gasoline (Group 48/H6): Optima YellowTop DH6 (AGM, deep cycle/starting) or RedTop H6 (AGM, starting)
  • Gasoline (Group 94R/H7): Optima YellowTop DH7 (AGM, deep cycle/starting) or RedTop H7 (AGM, starting)
• DieHard:
  • Diesel (Group 31): DieHard Platinum AGM Group 31
  • Gasoline (Group 48/H6): DieHard Platinum AGM Group 48/H6
  • Gasoline (Group 94R/H7): DieHard Platinum AGM Group 94R/H7
• Odyssey:
  • Diesel (Group 31): Odyssey Extreme Series PC1220 (AGM) or 31-PC2150 (AGM)
  • Gasoline (Group 48/H6): Odyssey Extreme Series H6-AGM (AGM)
  • Gasoline (Group 94R/H7): Odyssey Extreme Series H7-AGM (AGM)
• ACDelco (OEM supplier):
  • Check with your local GM dealer for exact ACDelco part numbers specific to your 2500HD engine and trim.

AGM vs. flooded — which does this vehicle need?

For your 2020 GMC Sierra 2500HD, you essentially have the choice between an Absorbent Glass Mat (AGM) battery and a traditional flooded (lead-acid) battery. While your truck will operate with a high-quality flooded battery, AGM is highly recommended, especially for diesel models and trucks equipped with extensive electronics or accessories.

Many 2020 Sierra 2500HD trucks, particularly higher trims and diesel variants, may have come from the factory with an AGM battery. AGM batteries offer several advantages:

• Durability: They are more resistant to vibration and impacts, which is beneficial for a heavy-duty truck.
• Performance: AGMs generally provide stronger starting power and maintain voltage better over their lifespan.
• Longevity: They tend to last longer than flooded batteries under similar conditions.
• Maintenance-Free: AGMs are sealed and do not require water top-offs.
• Deep Cycle Capability: Better suited to handle the demands of modern trucks with numerous electrical accessories and longer periods of engine-off power draw.

Flooded batteries are typically less expensive upfront but may not offer the same longevity or robust performance, especially in demanding applications or extreme temperatures. Given the critical role of reliability in a heavy-duty truck, the investment in an AGM battery is usually worthwhile.

Post-installation relearn / reset procedure

After replacing the battery in your 2020 GMC Sierra 2500HD, it's good practice to perform a battery relearn or reset procedure. This helps the vehicle's computer system (specifically the Body Control Module or BCM and the charging system) to accurately monitor the new battery's state of charge and optimize charging.

Here’s a general procedure, though specific steps might vary slightly:

1. Install the new battery: Ensure all connections are clean and secure.
2. Start the engine: Allow the engine to idle for at least 5-10 minutes without touching the accelerator. This gives the BCM time to recognize the new battery.
3. Drive cycle: For optimal relearn, drive the vehicle on a varied cycle, including some city and highway driving. The vehicle's charging system will monitor the new battery's voltage and current characteristics to establish a new baseline.
4. Window Express-Up/Down (if applicable): You may need to reset express-up/down for power windows. To do this, fully lower the window, hold the button for a few seconds, then fully raise the window and hold the button again for a few seconds.
5. Radio/Clock: Reset your radio presets and clock as these will likely be lost during battery disconnect.

If you experience any persistent warning lights or electrical issues after a battery replacement, it