A deep cycle Group 24M marine battery is a lead-acid or AGM battery designed for prolonged energy delivery in marine applications, with a nominal voltage of 12V and capacity ranging from 70–100Ah. Unlike starter batteries, it features thicker plates to withstand repeated 80% depth-of-discharge (DOD) cycles, powering trolling motors, navigation systems, and onboard electronics. Group 24M denotes standardized dimensions (approx. 10.25″L x 6.8″W x 9.4″H) for compatibility with marine/RV battery trays. For example, a 12V 85Ah Group 24M AGM battery can sustain a 25A draw for 3–4 hours before recharging. Pro Tip: Pair with a marine-specific charger to prevent sulfation during partial-state charging.
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How does a deep cycle Group 24M differ from standard marine batteries?
A Group 24M deep cycle battery prioritizes sustained discharge over cranking amps, with plate structures optimized for 200–600 cycles at 50% DOD. Starter batteries use thinner plates for short 300–800A bursts but degrade below 50% DOD. Group 24M models typically offer 650–750 marine cranking amps (MCA) versus 800–1000MCA in dual-purpose alternatives. Practically speaking, using a starter battery for trolling motors might cut runtime by 40% compared to a true deep cycle design.
What are the key specs of Group 24M batteries?
Group 24M batteries deliver 12V output with capacities of 70–120Ah, translating to 840–1,440Wh. Reserve capacity averages 140–180 minutes at 25A draw. AGM variants typically weigh 45–60 lbs, while flooded lead-acid versions are 10% lighter. Charge voltage ranges from 14.4–14.6V (absorb) to 13.2–13.4V (float). For instance, a 100Ah model supporting 50A continuous discharge suits 55 lb-thrust trolling motors. Warning: Exceeding 50% DOD regularly reduces lifespan—a 100Ah battery should only discharge 50Ah between charges.
| Parameter | Group 24M Deep Cycle | Group 24 Starter |
|---|---|---|
| Cycle Life (50% DOD) | 400–600 cycles | 100–200 cycles |
| Plate Thickness | 2.5–3.5mm | 1.2–2.0mm |
| Typical Ah | 85Ah | 55Ah |
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FAQs
Yes, when paired with a 12V solar charge controller. Limit discharge to 70% DOD for solar applications—AGM versions handle 1,200+ cycles at this depth versus 500 cycles for flooded types.
Are Group 24M and Group 24 batteries interchangeable?
Check terminal placement—some Group 24M models shift posts 3–5mm for marine tray compatibility. Mismatched terminals risk cable strain and arcing.
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