What cars does a 51R battery fit?

A BCI Group 51R battery commonly fits many Honda Civics and CR‑Vs, Acura ILX/RSX and other Civic-based Acuras, plus several Nissan subcompacts such as the Versa, Juke, and Cube; however, exact fitment varies by year, trim, and options, so you should verify against your owner’s manual or VIN. In general, 51R is a compact, narrow battery with reversed terminals used widely in small-to-midsize Japanese vehicles from the early 2000s through the 2020s. Below, we break down what “51R” means, which vehicles typically use it, common exceptions, and how to double-check compatibility.

What “51R” means

“51R” is a North American BCI group size that defines the battery’s footprint, height, and terminal orientation. The “R” indicates reversed terminals compared with a standard Group 51. Most 51R batteries use standard top SAE posts and are available in flooded, EFB, or AGM constructions.

Core dimensions and specs

The following details explain the typical physical and performance characteristics that determine fit and suitability.

• Dimensions (approx.): 9.37 in L × 5.06 in W × 8.8–8.9 in H (238 × 129 × 224 mm)
• Terminal orientation: Reversed vs. Group 51 (positive on the right when posts face you)
• Typical CCA range: ~410–500 A (varies by brand/model)
• Reserve capacity: ~65–85 minutes (varies)
• Chemistries: Flooded lead-acid, EFB (enhanced flooded), and some AGM options

These specifications ensure the battery physically fits the tray, the cables reach the correct posts, and the capacity suits the vehicle’s electrical demands and climate.

Vehicles that commonly use Group 51R

This list highlights mainstream models frequently specified for Group 51R from the factory in North America. Because automakers sometimes change battery groups across generations, trims, or for cold-climate packages and start-stop systems, always verify with your manual or a parts lookup by VIN.

• Honda: Civic (approximately 2001–2021, most trims); CR‑V (approximately 2002–2022, many trims); Element (2003–2011); Insight (2010–2014)
• Acura: ILX (2013–2022); RSX (2002–2006); CSX (Canada, 2006–2011); many older Integra models (mid‑1990s to 2001)
• Nissan: Versa sedan and Versa Note (2007–2019); Cube (2009–2014); Juke (2011–2017); Leaf (many 2011–2019 models use a 51R-size 12V battery)

The above vehicles are among the most common 51R applications, especially Civic-based platforms and Nissan subcompacts. Nonetheless, year-to-year differences mean you should confirm before purchasing.

Notable exceptions and easy mix-ups

Several vehicles appear similar under the hood or are closely related to models that use 51R, but they require different group sizes or terminal layouts. The following examples help you avoid ordering the wrong battery.

• Honda Fit (2007–2020): Commonly uses Group 151R (smaller than 51R)
• Honda HR‑V (2016–2022): Often uses Group 151R from the factory
• Newer Civic/Integra (2022–present in many trims): Frequently moved to Group 47/H5, sometimes with EFB/AGM for idle‑stop
• Toyota Prius (various years): Uses specialized JIS sizes (e.g., S46B24R) rather than 51R
• Mazda MX‑5 Miata (various years): Uses a compact AGM battery specific to its trunk/battery well
• Group 51 vs. 51R: Same footprint, opposite terminal orientation—many Honda/Acura applications require the “R”

When in doubt, check the original battery label and cable routing: if the positive cable reaches the right‑hand post with posts facing you, you likely need “51R,” not “51.”

How to verify fitment for your car

Before buying, follow these steps to make sure a Group 51R will fit and function correctly in your vehicle.

1. Consult the owner’s manual or under‑hood label for the specified BCI group and any start‑stop (EFB/AGM) requirements.
2. Use a VIN-based fitment lookup on a reputable battery retailer’s site or the automaker’s parts catalog.
3. Measure your battery tray and hold‑down, and confirm the cables comfortably reach the correct terminals (R orientation).
4. Match capacity to climate: choose higher CCA for cold regions and consider EFB/AGM if the vehicle has heavy accessory loads or idle‑stop.
5. Check warranty and reserve capacity to ensure performance aligns with your driving profile.

These checks guard against surprises like cables that won’t reach, trays that don’t clamp properly, or start‑stop systems that underperform with the wrong battery type.

Alternatives and upgrades commonly considered

Some owners consider alternate group sizes or constructions to improve cold‑start performance, longevity, or accessory headroom. Here are typical paths and their caveats.

• 51 vs. 51R: Use only if terminal orientation matches your cables; otherwise, you risk short leads or crossed cables.
• Higher‑output 51R: Choose models with higher CCA/reserve capacity for cold climates or frequent short trips.
• EFB/AGM 51R: Recommended for vehicles with idle‑stop or heavy electrical loads; ensure your charging system supports it.
• Group 35 “big battery” swap (Honda Civic/CR‑V owners): Often requires a tray/hold‑down and sometimes cable adjustments; verify space and polarity.

Any deviation from the OEM group should be planned carefully: confirm spacing, hold‑down compatibility, and cable reach before committing to a non‑standard size.

Key specs at a glance

For quick reference, these are the attributes you’ll match when deciding whether a 51R suits your vehicle.

• BCI Group: 51R (reversed terminals)
• Approx. size: 238 × 129 × 224 mm (L × W × H)
• Posts: SAE top posts; positive on right when facing the posts
• Capacity: Typically 410–500 CCA; 65–85 min reserve capacity (varies by model)
• Chemistries: Flooded, EFB, and some AGM options available

Matching these parameters to your vehicle’s requirement ensures proper fit, safe cable routing, and reliable starting performance across seasons.

Summary

A Group 51R battery fits a wide range of small-to-midsize Japanese vehicles—most notably many Honda Civics and CR‑Vs, Acura ILX/RSX, and Nissan Versa/Juke/Cube, and numerous 2010s Nissan Leafs—provided the trim and year call for this reversed‑terminal compact size. Because fitment can vary within a model line, always confirm by manual or VIN, pay attention to the “R” terminal orientation, and consider EFB/AGM where start‑stop or heavy accessory use applies.

What does the R mean in a 51R battery?

The “51R” designation refers to the battery’s size and terminal orientation, with the “R” indicating that the positive terminal is on the right side when the battery is viewed from the front.

Are all 51R batteries the same size?

Group 51 and 51R batteries have nearly the same dimensions, typically measuring around 9.3 x 5.1 x 8.7 inches.

What battery goes into a 2018 Honda Civic?

Duralast Group Size 51R Battery 51R-DL.

What cars use a 51R battery?

Groups 35 and 51R
It is often found in Japanese Cars and Trucks from Toyota, Nissan, Mitsubishi, Subaru, Acura, and in some older American Cars. The Group-51 Battery is found in Hondas, Nissan GTRs, and some other Japanese Cars.