What Is Duralast AGM 31M-AGM Group 31T Battery?

The Duralast AGM 31M-AGM Group 31T Battery is a high-performance, maintenance-free lead-acid battery designed for demanding applications. As an AGM (Absorbent Glass Mat) type, it uses fiberglass separators to immobilize electrolyte, enabling leak-proof operation and vibration resistance. With a Group 31T designation, it meets standardized dimensions (typically ≈13×6.9×9.4 inches) and terminal configuration for compatibility in trucks, marine systems, and industrial equipment. Its thick lead-calcium plates and pressurized valve regulation optimize cycle life (1,200+ cycles at 50% DoD) and cold-cranking performance (900–1,000 CCA).

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How does AGM technology enhance battery performance?

AGM batteries utilize glass mat separators and oxygen recombination to eliminate electrolyte spillage while boosting efficiency. The compressed fiberglass mats retain 95–98% of sulfuric acid, creating a starved-electrolyte system that enables gas recombination during charging. Pro Tip: AGM batteries self-discharge 1–3% monthly versus 5–15% in flooded batteries—ideal for seasonal equipment storage.

AGM batteries employ recombinant technology where 99% of oxygen generated at the positive plate migrates to the negative plate, reacting with hydrogen to form water. This closed-loop system minimizes water loss, allowing maintenance-free operation. Compared to flooded batteries, AGM units deliver 30% faster recharge rates due to lower internal resistance (2–4 mΩ vs. 6–10 mΩ). For example, a Group 31T AGM battery can recharge to 80% capacity in 4–5 hours with a 40A charger. However, improper charging above 14.8V accelerates grid corrosion. Always use AGM-compatible chargers with temperature compensation.

What applications suit Group 31T batteries?

Group 31T’s high capacity (90–130Ah) and vibration resistance make them ideal for commercial vehicles, marine systems, and renewable energy storage. Their robust construction handles deep-cycle demands in trolling motors or solar arrays while providing reliable engine starts.

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FAQs

Can AGM Group 31T batteries be mounted sideways?

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Yes—the immobilized electrolyte allows any orientation except inverted. However, keep vents unobstructed to prevent pressure buildup during gas venting.

How long do AGM 31T batteries last in RV applications?

Typically 4–7 years with proper maintenance: keep state of charge ≥50%, avoid discharging below 10.5V, and equalize quarterly at 15.5V for 2–4 hours.

Product: RG72105P