A Group 31 battery typically measures approximately 13 inches (33 cm) in length, 6.8 inches (17.3 cm) in width, and 9.4 inches (24 cm) in height. These dimensions make it suitable for high-power applications like marine systems, RVs, and commercial vehicles. Weight ranges from 55-75 lbs depending on construction (flooded, AGM, or lithium). Terminal types vary between SAE post or dual-purpose configurations.
What Is a Group Size 24 Battery?
How Do Group 31 Battery Dimensions Compare to Other Battery Groups?
Group 31 batteries are larger than Group 24 (10.25″x6.8″x8.9″) and Group 27 (12.4″x6.8″x9″) but share similar widths. They provide 30-50% more capacity than Group 27 while maintaining comparable height for vehicle tray compatibility. Unlike compact Group 34/78 batteries (10.25″x7″x7.8″), Group 31 prioritizes capacity over space efficiency.
| Battery Group | Length | Width | Height | Typical Use |
|---|---|---|---|---|
| 24 | 10.25″ | 6.8″ | 8.9″ | Passenger vehicles |
| 31 | 13″ | 6.8″ | 9.4″ | Commercial trucks |
| 34/78 | 10.25″ | 7″ | 7.8″ | Compact vehicles |
The dimensional differences become critical in engine compartments with limited space. While Group 31 offers superior cold cranking amps (CCA) for diesel engines, some automotive applications require modified battery trays. Marine enthusiasts often choose Group 31 despite its larger footprint because its extra height accommodates thicker lead plates for deep-cycle durability. Commercial fleet managers appreciate that Group 31 maintains the same width as smaller groups, allowing standardized tray designs across vehicle types.
Top 5 best-selling Group 14 batteries under $100
| Product Name | Short Description | Amazon URL |
|---|---|---|
|
Weize YTX14 BS ATV Battery  |
Maintenance-free sealed AGM battery, compatible with various motorcycles and powersports vehicles. | View on Amazon |
|
UPLUS ATV Battery YTX14AH-BS  |
Sealed AGM battery designed for ATVs, UTVs, and motorcycles, offering reliable performance. | View on Amazon |
|
Weize YTX20L-BS High Performance  |
High-performance sealed AGM battery suitable for motorcycles and snowmobiles. | View on Amazon |
|
Mighty Max Battery ML-U1-CCAHR  |
Rechargeable SLA AGM battery with 320 CCA, ideal for various powersport applications. | View on Amazon |
|
Battanux 12N9-BS Motorcycle Battery  |
Sealed SLA/AGM battery for ATVs and motorcycles, maintenance-free with advanced technology. | View on Amazon |
Are There Variations in Group 31 Battery Dimensions Between Brands?
Variations exist within 0.3″ tolerance: Odyssey 31-PC2150 measures 13.11″x6.77″x9.61″ vs Renogy’s 12.95″x6.77″x9.21″. Terminal height differences (0.5-1.2″ above case) impact cable routing. Some lithium variants (Battle Born 12V 100Ah) reduce height to 8.9″ using prismatic cells. Always verify manufacturer specs before installation.
| Brand | Model | Length | Width | Height |
|---|---|---|---|---|
| Odyssey | 31-PC2150 | 13.11″ | 6.77″ | 9.61″ |
| Renogy | RNG-31D | 12.95″ | 6.77″ | 9.21″ |
| Battle Born | BB10012 | 12.99″ | 6.73″ | 8.94″ |
These subtle variations require careful planning in constrained spaces. Marine installations need extra clearance for terminal corrosion prevention sprays, while RV battery compartments must account for ventilation gaps. Lithium-ion versions demonstrate the most dramatic size reductions, with some models achieving 20% height reduction through cell stacking innovations. Always cross-reference the manufacturer’s installation guide – even 0.25″ differences can prevent proper tray engagement in certain truck models.
What Applications Require Group 31 Battery Sizes?
Commercial trucks use Group 31 for cold cranking (800-1000 CCA) and accessory power. Marine applications leverage their 180-220Ah capacity for trolling motors and electronics. Off-grid solar systems utilize multiple Group 31 AGM/LiFePO4 units due to deep-cycle durability. Heavy-duty RVs require this size for extended inverter runtime (2,000-3,000W loads).
How Does Group 31 Battery Weight Affect Installation?
At 65-75 lbs for AGM versions, proper mounting is critical. Marine installations require ABYC-compliant trays with 360° restraint. Automotive use needs J-hook compatible trays (≥1/4″ steel). Lithium variants (31 lbs) allow roof-mounted solar setups but still require vibration isolation. Always distribute weight evenly across vehicle chassis to prevent frame stress.
What Terminal Configurations Exist for Group 31 Batteries?
Standard options include top-post (SAE 5/16″), side-post (GM-style), or dual terminal designs. Marine versions add 3/8″ stud terminals for trolling motor connections. Lithium models feature M8 bolts for high-current lugs. Some deep-cycle variants incorporate threaded inserts for bus bar integration. Terminal orientation (left/right positive) varies – check polarity markings before connecting.
Expert Views
“Group 31’s dominance stems from its optimal balance between BCI standardization and performance. While newer lithium formats challenge size conventions, 90% of commercial fleets still specify Group 31 due to parts commonality. The real innovation is in case materials – we’re now seeing UV-resistant composites that maintain dimensions while shaving 15% weight.” – Industrial Battery Engineer, Johnson Controls
Conclusion
Group 31 batteries maintain standardized dimensions (13″x6.8″x9.4″) while evolving in capacity and chemistry. Their size supports 200-300Ah deep-cycle performance unattainable in smaller form factors. When selecting, prioritize case material compatibility with your application’s vibration profile and verify terminal types against existing cabling.
FAQ
- Can I replace a Group 27 with Group 31?
- Only if your battery tray has 13″x7″ clearance and sufficient weight capacity. Group 31 provides 40% more capacity but requires upgraded hold-down hardware.
- Do all Group 31 batteries have same terminal positions?
- No. Trojan’s J305P uses reversed polarity (positive on right) vs standard configurations. Always verify terminal layout using manufacturer diagrams.
- How long do Group 31 batteries last?
- Flooded: 4-6 years. AGM: 6-8 years. Lithium: 10+ years. Actual lifespan depends on depth of discharge (keep AGM above 50%, lithium above 20%).