2016 Ram 3500 Battery Size & Replacement Specs

When it’s time to replace the battery in your heavy-duty rig, getting the right specs is critical—especially if you’re running a diesel. As an ASE-certified master technician, I’ve replaced countless batteries in 4th Generation Ram HD trucks. Below is the complete battery replacement guide for the 2016 Ram 3500, whether you’ve got the 5.7L Hemi, the 6.4L Hemi, or the legendary 6.7L Cummins turbo diesel.

Quick answer: 2016 Ram 3500 Battery Specs

Depending on your engine, the 2016 Ram 3500 takes different battery setups. The most critical distinction is whether you need a single battery (gas) or a dual-battery setup (diesel).

• BCI Group Size:
  • 6.7L Cummins Diesel: Dual Group 94R (also known as H7) or Dual Group 65 (check your battery trays, as Ram transitioned between these).
  • 5.7L & 6.4L Hemi Gas: Single Group 65.
• Cold Cranking Amps (CCA): Minimum 730 CCA per battery, though 800–850 CCA is highly recommended for cold climates and diesel applications.
• Reserve Capacity (RC): 130 to 140 minutes minimum.
• AGM vs. Flooded: AGM (Absorbent Glass Mat) is highly recommended for the Cummins diesel and high-trim gas models with heavy electronics. Standard flooded is acceptable for base model gas engines.
• Terminal Layout: Standard Top Post (Positive on Left for Group 65; Positive on Right for Group 94R/H7).
• Physical Dimensions (Group 94R/H7): Approx. 12.4" L x 6.9" W x 7.5" H.
• Physical Dimensions (Group 65): Approx. 12.1" L x 7.5" W x 7.6" H.
• Dual-Battery Setup (Diesel Only): The 6.7L Cummins requires two identical batteries wired in parallel to provide the massive cranking amps needed for high-compression diesel ignition and the grid heater. Always replace both batteries at the same time.

Replacement battery options

When replacing batteries in a 1-ton truck, don't skimp on quality. Here are some of the most reliable replacement options on the market:

• DieHard Platinum AGM (Group 94R / H7): An exceptional choice for diesel owners needing deep cycling capabilities and high vibration resistance.
• Interstate MTZ AGM (Group 65 or 94R): Interstate’s top-tier AGM battery, offering premium starting power and an excellent warranty.
• Odyssey Extreme Series (Group 65 or 94R): The gold standard for heavy-duty trucks, offering massive CCA and deep-cycle reserve capacity.
• Optima YellowTop (Group 94R / H7): A great deep-cycle AGM option for trucks running aftermarket accessories like winches or inverters.
• ACDelco Gold AGM (Group 94R or 65): A solid, OEM-quality replacement that balances performance and price.

AGM vs flooded — which does this vehicle need?

While a base tradesman 2016 Ram 3500 with a gas engine can perfectly run on a standard flooded lead-acid battery, AGM is the way to go for the 6.7L Cummins diesel.

The Cummins engine relies on a grid heater (instead of traditional glow plugs) to warm the intake air on cold starts. This grid heater pulls a massive amount of amperage. AGM batteries recharge up to five times faster, handle deep voltage drops much better, and are far more resistant to the heavy vibrations produced by a diesel engine. If you use your 3500 for towing, plowing, or have high-draw electronics, upgrade to AGM.

Post-installation relearn / reset procedure

Unlike some modern European vehicles, the 2016 Ram 3500 does not require a complicated scan-tool battery registration. However, it does feature an Intelligent Battery Sensor (IBS) on the negative terminal.

After installing the new batteries:

1. Reconnect the positive terminals first, then the negative terminals.
2. Ensure the IBS connector on the negative terminal is plugged in securely.
3. Let the truck sit completely undisturbed (doors closed, key out of the ignition) for a few hours. The IBS module will passively relearn the new battery’s state of charge.
4. You may need to reset your radio presets and clock, but the transmission and engine modules will adapt automatically after a few drive cycles.

Signs of a failing battery

HD trucks will often warn you before they leave you stranded. Look out for:

• Slow or sluggish cranking: Especially noticeable on cold mornings when the diesel grid heater is cycling.
• "Battery Saver Mode" messages: The dash may display this if system voltage drops too low.
• Flickering interior or dash lights during engine cranking.
• Corrosion build-up around the battery posts and cables, a sign of off-gassing.
• Check Engine Light or random electrical gremlins: Low voltage can cause various modules (like the ABS or Trailer Brake Controller) to throw phantom codes.

Common battery issues for this generation

One of the most common issues on the 2016 Ram 3500 (specifically the Cummins) is the failure of the crossover cable that links the passenger and driver-side batteries. If this cable develops high resistance from internal corrosion, one battery will overcharge while the other undercharges, boiling one and killing the other.

Always check your battery terminals and the crossover cable for heat and corrosion when replacing your batteries. Also, remember the golden rule of dual batteries: never mix old and new batteries, and never mix different brands or group sizes.

If you need help diagnosing electrical issues, testing your alternator, or swapping out these heavy batteries, don't hesitate to seek professional help. Find a trusted shop on Repairius.