2021 Ram 2500 Battery Size & Group

Quick answer

• BCI Group Size: Group 65 (Gas), Dual Group 48 (Diesel)
• CCA Rating: 730-800 CCA (Gas), 750 CCA each (Diesel)
• Reserve Capacity: 130-160 minutes (Gas), 140 minutes each (Diesel)
• AGM vs. Flooded: Depends on original equipment and owner preference; consult your owner's manual. Many factory batteries are flooded lead-acid, but AGM is a popular upgrade.
• Terminal Layout: Top post
• Physical Dimensions (Group 65): Approximately 12" L x 7.5" W x 7.5" H
• Dual-Battery Setup: Yes, for diesel models, two Group 48 batteries are used.

Replacement battery options

• Interstate:
  • Group 65 (Gas): MTP-65
  • Group 48 (Diesel): MTP-48/H6
• Optima:
  • Group 65 (Gas): RedTop 65
  • Group 48 (Diesel): YellowTop DH6
• DieHard:
  • Group 65 (Gas): Platinum AGM Group 65
  • Group 48 (Diesel): Platinum AGM Group 48
• Odyssey:
  • Group 65 (Gas): 65-PC1750
  • Group 48 (Diesel): H6-1500
• ACDelco:
  • Group 65 (Gas): 65AGMHR
  • Group 48 (Diesel): 48AGMHR

AGM vs flooded — which does this vehicle need?

The 2021 Ram 2500, depending on its engine and trim, may have come with either a flooded lead-acid battery or an Absorbed Glass Mat (AGM) battery from the factory. Generally, gasoline models often come with a flooded battery, while diesel models, especially higher trims, might feature AGM batteries due to their higher power demands and ability to withstand deeper cycles.

Flooded lead-acid batteries are the traditional choice, offering good performance at a lower cost. They require occasional maintenance (checking and topping off electrolyte levels) in some designs, though many modern versions are "maintenance-free."

AGM batteries are a more advanced technology. They are sealed, maintenance-free, more resistant to vibration, and can handle deeper discharge cycles without significant damage. This makes them ideal for vehicles with heavy electrical loads, such as modern trucks equipped with numerous electronic accessories, or for those who frequently use their vehicle for tasks like plowing or operating auxiliary equipment. While they are more expensive upfront, their enhanced durability and performance can justify the cost for many owners.

To determine the exact type your 2021 Ram 2500 came with, it