Group 31 batteries are heavy-duty lead-acid or lithium-ion cells designed for high-capacity applications like RVs, marine systems, and commercial trucks. Their specs include 12V nominal voltage, 100–125Ah capacity, and 800–1,000 CCA (cold cranking amps). Dimensions average 13×6.8×9.4 inches, with AGM (absorbent glass mat) variants offering spill-proof operation. Ideal for deep-cycle use, they support sustained loads like inverters and winches. Lithium Group 31 models (e.g., LiFePO4) provide 200+ Ah with 50% weight reduction.
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What defines Group 31 battery dimensions?
Group 31 batteries follow SAE J537 standards with typical dimensions of 13″ (L) x 6.8″ (W) x 9.4″ (H). Weight ranges from 60 lbs (flooded lead-acid) to 35 lbs (LiFePO4). Terminal types include top-post (SAE) or side-post, with 20mm bolt spacing. Pro Tip: Measure your battery tray clearance—oversized units can strain mounting systems during vibration.
Beyond basic dimensions, Group 31’s polarity arrangement (positive right/left) varies by manufacturer—cross-check before installation. For example, a Deka Intimidator AGM Group 31 measures 13.03×6.85×9.41 inches and weighs 73.9 lbs, while a Battle Born LiFePO4 version shrinks to 12.75×6.875×9.25 inches at 31 lbs. Technical specs like internal resistance (≤5mΩ for AGM) impact compatibility with high-current devices like trolling motors. Always verify terminal height (e.g., ¾” for marine applications) to avoid cable strain.
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| Product Name | Short Description | Amazon URL |
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Weize YTX14 BS ATV Battery  |
Maintenance-free sealed AGM battery, compatible with various motorcycles and powersports vehicles. | View on Amazon |
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UPLUS ATV Battery YTX14AH-BS  |
Sealed AGM battery designed for ATVs, UTVs, and motorcycles, offering reliable performance. | View on Amazon |
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Weize YTX20L-BS High Performance  |
High-performance sealed AGM battery suitable for motorcycles and snowmobiles. | View on Amazon |
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Mighty Max Battery ML-U1-CCAHR  |
Rechargeable SLA AGM battery with 320 CCA, ideal for various powersport applications. | View on Amazon |
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Battanux 12N9-BS Motorcycle Battery  |
Sealed SLA/AGM battery for ATVs and motorcycles, maintenance-free with advanced technology. | View on Amazon |
Where are Group 31 batteries commonly used?
Group 31 batteries power high-demand systems in marine (fishfinders, thrusters), RV (solar storage, inverters), and industrial (backup power, forklifts). Their deep-cycle design handles 50–80% daily depth of discharge (DoD) in AGM/LiFePO4 formats. Flooded versions remain popular for budget-conscious truck starters.
When considering applications, Group 31’s reserve capacity (180–220 minutes) makes them ideal for off-grid setups. For instance, a 100Ah LiFePO4 Group 31 battery can run a 1,000W RV inverter for 1.5 hours at full load. In marine contexts, dual Group 31 AGM batteries often power 36V trolling motors with 30+ lbs thrust. Pro Tip: Use marine-rated models with vibration resistance—rough waters can dislodge poorly secured cells. What happens if you pair mismatched batteries? Imbalanced charging reduces lifespan by 40–60%.
| Application | Key Specs | Recommended Type |
|---|---|---|
| RV Solar | 200Ah LiFePO4, 3,000+ cycles | Lithium |
| Marine Starter | 950 CCA, corrosion-resistant | AGM |
| Truck Backup | 125Ah, low self-discharge | Flooded |
AGM vs. Flooded Group 31 Batteries: Which is better?
AGM Group 31 batteries offer maintenance-free operation, 10–12-year lifespan, and vibration resistance, while flooded types cost 50% less but require monthly watering. AGM’s lower internal resistance supports faster recharging (20–25% quicker).
Practically speaking, AGM excels in harsh environments—think bass boats bouncing across waves or RVs traversing dirt roads. Their valve-regulated design minimizes acid spills even when tilted 45°. Flooded batteries, however, still dominate trucking fleets due to replaceable cells. For example, an Interstate Group 31 flooded battery delivers 1,000 CCA for diesel cold starts at half the cost of AGM. But what about charging? AGM needs precise voltage (14.4–14.6V absorption), while flooded tolerates ±0.5V fluctuations.
| Feature | AGM | Flooded |
|---|---|---|
| Cost | $350–$600 | $180–$300 |
| Maintenance | None | Monthly |
| Lifespan | 10–12 years | 4–6 years |
How to charge Group 31 batteries correctly?
Use multi-stage chargers with AGM/LiFePO4 presets. Lead-acid Group 31 requires 14.4–14.8V absorption; lithium needs 14.6V (3.65V/cell). Charging current should be 10–30% of capacity (e.g., 20A for 200Ah LiFePO4).
Beyond voltage settings, temperature compensation is critical—AGM charging drops 0.03V/°F below 77°F. For solar setups, MPPT controllers with adaptive algorithms prevent overcharging. A real-world example: The NOCO Genius10 charges Group 31 AGM at 10A with automatic voltage detection. Pro Tip: Equalize flooded batteries every 10 cycles (15.5V for 2–4 hours) to dissolve sulfate buildup. What if you skip equalization? Capacity loss accelerates by 1–2% weekly.
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What maintenance do Group 31 batteries need?
Flooded types need monthly electrolyte checks (distilled water refills) and terminal cleaning. AGM/LiFePO4 require annual voltage checks (12.7–13.2V resting) and torque inspections (8–10 Nm terminals). Store at 50–80% charge in cool, dry environments.
Maintenance-wise, corrosion is the silent killer. Apply anti-corrosion gel (e.g., NOCO NCP2) to lead terminals every 6 months. For fleets, load-test batteries quarterly—a 100Ah AGM should maintain 10.5V under 50A load for 15 minutes. Pro Tip: Use infrared cameras during testing—hotspots >10°F above ambient indicate weak cells. Imagine a delivery truck’s dual Group 31 setup: Neglecting terminal torque leads to arcing, melting cables within months.
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FAQs
Yes, if tray space allows—Group 31 offers 20–35% more capacity but requires updated hold-down brackets due to larger dimensions.
Do lithium Group 31 batteries work with existing lead-acid chargers?
No—most lead-acid chargers lack LiFePO4 voltage limits. Use only compatible chargers to prevent cell overvoltage (≥3.7V/cell risks thermal runaway).
What’s the lifespan of AGM Group 31 batteries?
8–12 years with proper charging; deep discharges below 50% DoD cut life by 50%. Regularly check resting voltage—below 12.4V indicates sulfation.