2018 Ram 3500 Battery Size, Group & Replacement Guide

Quick answer

• BCI Group Size: Group 94R (H7) (two batteries)
• Cold Cranking Amps (CCA): 730-850 CCA each
• Reserve Capacity (RC): 130-150 minutes each
• AGM vs Flooded Requirement: AGM is strongly recommended
• Terminal Layout: Right-hand positive
• Physical Dimensions: Approximately 12.4" L x 6.9" W x 7.5" H
• Dual-battery setup: Yes, all 2018 Ram 3500 trucks with the 6.7L Cummins diesel engine feature a mandatory dual-battery configuration for increased cranking power and electrical system stability.

Replacement battery options

• Interstate: MTX-94R/H7
• Optima: DH7 YELLOWTOP
• DieHard: Platinum AGM Battery, Group Size H7, 850 CCA (Part # H7-AGM)
• Odyssey: ODP-AGM94R H7 L4
• ACDelco: 94RAGM

AGM vs flooded — which does this vehicle need?

Your 2018 Ram 3500 came from the factory with two Absorbent Glass Mat (AGM) batteries, and it's critical to replace them with AGM batteries as well. The complex electrical system, featuring numerous modules, sensors, and the high-demand grid heater for the Cummins engine, requires the stable voltage and deep-cycling capability that only an AGM battery can provide. Flooded batteries will not hold up to the intense electrical demands and vibrations of the Ram 3500, leading to premature failure and potential damage to sensitive electronics.

Post-installation relearn / reset procedure

After a battery replacement, your 2018 Ram 3500 requires a reset procedure to ensure all systems function correctly. After installing the new batteries, turn the ignition to the 'RUN' position (without starting the engine) for about 10 seconds to allow the modules to initialize. Then, start the engine and let it idle for a few minutes. You may need to reset your radio presets and clock. In some cases, a scan tool may be required to clear any stored fault codes that occurred during the battery swap.

Signs of a failing battery

• Slow Engine Crank: The most obvious sign. The 6.7L Cummins requires a massive amount of power to turn over, and weak batteries will struggle, especially in cold weather.
• "Battery Saver Mode" Message: The truck's computer will actively try to conserve power if it detects low voltage from the batteries.
• Dimming Lights: Headlights or interior lights may flicker or dim, especially at idle or when using accessories like the power windows.
• Electronic Glitches: The Uconnect system may act erratically, or you might see random warning lights on the dashboard.

Common battery issues for this generation

The 2013-2018 generation of Ram HD trucks is known for its demanding electrical system. The most common issue is premature battery failure caused by either installing incorrect (flooded) batteries or by a single failing battery taking the other one down with it. It's crucial to always replace both batteries at the same time. Another common problem is loose or corroded battery terminals, which can mimic the symptoms of a failed battery. Regular inspection and cleaning of the battery posts and cable ends are highly recommended.

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