BCI Group Batteries

BCI Group 51 and 51R Batteries, The Complete Guide

BCI Group 51 and 51R Batteries, The Complete Guide

BCI Group 51 and 51R batteries are renowned in the automotive industry for reliable performance. Group 51 suits large and older vehicles like Honda and Nissan, while 51R is versatile for broader applications. Both offer compact design, AGM technology, high CCA ratings, and maintenance-free operation. They find use in automobiles, marine vessels, motorcycles, and other devices. Let’s explore the differences and features of these battery groups.

What are BCI Group 51 Battery?

BCI Group 51 batteries, measuring approximately 9.3 inches (L) x 5.0 inches (W) x 8.75 inches (H), feature left-side battery posts. Designed for starting and dual-purpose applications, they offer excellent vibration resistance, making them suitable for large and older vehicles like Honda, Nissan, and Mazda. Recommended for stable power supply.

Dimensions: Approximately 9.3 inches (L) x 5.0 inches (W) x 8.75 inches (H)

Battery Post Position: The battery post is on the left side.


Designed for starting and dual-purpose applications.

Excellent vibration resistance, ensuring stability during bumpy rides.

Suitable for large and older vehicles due to its standard rectangular box dimensions.

Often used in Japanese car brands like Honda, Nissan, and Mazda.

Recommendation: If you’re looking for a reliable battery with stable power, the Group 51 battery is a solid choice.

What are BCI Group 51R Battery?

BCI Group 51R batteries, with dimensions akin to Group 51 (about 9.3″L x 5.0″W x 8.75″H) and right-side battery posts, suit starting and dual-purpose applications. Offering vibration resistance and stable power output, they find use beyond automotive. The Duracell Ultra BCI Group 51R battery provides 450 cold-cranking amps (CCA) for reliable starts, recommended for various applications.

Dimensions: Same as the Group 51 battery (approximately 9.3 inches (L) x 5.0 inches (W) x 8.75 inches (H)).

Battery Post Position: The battery post is on the right side.


Also designed for starting and dual-purpose applications.

Shares the same vibration resistance benefits.

Widely used in various applications beyond automotive due to its stable power output.

Recommendation: The Duracell Ultra BCI Group 51R battery is a top choice, offering 450 cold-cranking amps (CCA) for reliable starts, even in cold weather.

Remember to measure your battery compartment before purchasing to ensure a perfect fit. Whether you choose Group 51 or 51R, both provide dependable performance for your vehicle!

Similarities and Differences of Group 51 and 51R Batteries

Both BCI Group 51 and 51R batteries share similar dimensions of approximately 9.3 x 5.0 x 8.75 inches. However, they differ in battery post position: Group 51 has left-side posts, while Group 51R has right-side posts. Both are designed for starting and dual-purpose applications, with Group 51 commonly used in older vehicles and Group 51R being versatile for various applications.

  1. Dimensions:
    • Both battery groups have approximately the same dimensions: around 9.3 inches (L) x 5.0 inches (W) x 8.75 inches (H) .
    • The key difference lies in the battery post position:
      • Group 51: Battery post on the left side.
      • Group 51R: Battery post on the right side.
  2. Applications:
    • Both groups are designed for starting and dual-purpose applications.
    • They offer excellent vibration resistance and stability during driving.
  3. Usage:
    • Group 51 is commonly found in large and older vehicles, especially Japanese car brands like Honda, Nissan, and Mazda .
    • Group 51R is versatile and used beyond automotive applications due to its stable power output.
  4. Recommendations:
    • For reliable starts, consider the Duracell Ultra BCI Group 51R battery with 450 cold-cranking amps (CCA) .
    • Both batteries provide dependable performance, so choose based on your specific needs.

In summary, while they are similar, the battery post position and specific applications differentiate Group 51 from Group 51R.

Key Features of BCI Group 51/51R Batteries

BCI Group 51/51R batteries excel in compactness and performance. Features include compact design for small vehicles, AGM technology for durability, high CCA ratings for reliable starts, maintenance-free operation, versatility across vehicle types, and lightweight construction. These qualities make them ideal for vehicles with limited space requirements, ensuring reliable power in various conditions.

Key features include:

  1. Compact Design: Ideal for vehicles with limited space, such as small cars and motorcycles.
  2. AGM Technology: Many Group 51/51R batteries utilize Absorbent Glass Mat (AGM) technology, offering enhanced durability and vibration resistance.
  3. High CCA Ratings: Despite their small size, these batteries often boast impressive Cold Cranking Amps (CCA) ratings, ensuring reliable starting power in various weather conditions.
  4. Maintenance-Free Operation: Typically, Group 51/51R batteries are maintenance-free, eliminating the need for electrolyte checks or water refills.
  5. Versatility: Suitable for a wide range of vehicles, including compact cars, motorcycles, and power sport vehicles.
  6. Lightweight Construction: Weighing between 25 and 35 pounds (11 – 16 kg) on average, they provide ample power without adding unnecessary weight to the vehicle. Overall, BCI Group 51/51R batteries combine compactness, reliability, and versatility, making them a popular choice for vehicles with limited space requirements.

What devices typically use BCI Group 51 and 51R Batteries?

BCI Group 51 and 51R batteries power automobiles including compact cars and hybrids, RVs, marine vessels, motorcycles, ATVs, powersports equipment, golf carts, and general uses like off-grid solar systems and emergency lighting. Their compact size, reliability, and stable power output make them versatile options for various devices. Always ensure compatibility with device requirements and consult manuals or professionals when replacing batteries.

Let’s explore some common uses for these battery groups:

  1. Automobiles:
    • Both Group 51 and 51R batteries are commonly used in smaller vehicles, including compact cars, sedans, and some hybrids.
    • They provide starting power for the engine and can handle deep-cycling when necessary.
    • The compact dimensions of these batteries make them suitable for vehicles with limited space.
  2. Recreational Vehicles (RVs):
    • Group 51 and 51R batteries are ideal for RVs, campers, and trailers.
    • They power various systems such as lights, appliances, and water pumps.
    • Their vibration resistance ensures stability during travel.
  3. Marine Applications:
  4. Motorcycles and ATVs:
    • Group 51 and 51R batteries are suitable for motorcycles, scooters, and all-terrain vehicles (ATVs).
    • They offer dependable starting performance for smaller engines.
  5. Powersports Equipment:
    • These batteries find use in powersports vehicles like jet skis, snowmobiles, and dirt bikes.
    • Their compact size and durability make them a good fit for these applications.
  6. Golf Carts:
    • Group 51 and 51R batteries power electric golf carts.
    • They provide the necessary energy for extended rounds on the golf course.
  7. Other General Applications:
    • Due to their stable power output, these batteries are also used in off-grid solar systemsemergency lighting, and small backup power setups.

Remember that when replacing a battery, it’s essential to consider the specific requirements of your device and ensure compatibility with the battery group, dimensions, and terminal positions. Always consult your vehicle’s manual or a professional to choose the right battery for your needs.

Best Sellers of BCI Group 51 and 51R Batteries in 2024

Battery Groups 51 and 51R have dimensions of 9.374 x 5.0625 x 8.8125 inches (238 x 129 x 223 mm) and are manufactured as Group 51 (positive terminal to the LEFT) and Group 51R (positive terminal to the RIGHT). Here are some of the most popular Group 51 and Group 51R batteries, with their most important features:

Model Battery Type
Cell Type
Capacity (Ah)
RC (min)
Weight (lbs/kg)
ACDelco ACDB24R Dual Purpose
29.11 lbs; 13.2 kg
Deka/East Penn 8AMU1R Starting

25 lbs; 11.3 kg
Delphi BU9051P MaxStart Dual Purpose
29.5 lbs; 13.4 kg
Optima 8071-167 D51 Dual Purpose
26 lbs; 11.8 kg
Optima 8073-167 D51R Dual Purpose
26 lbs; 11.8 kg

43 lbs; 19.5 kg
XS Power D5100 XS Dual Purpose

39.6 lbs; 18.0 kg
XS Power D5100R XS Dual Purpose

39.6 lbs; 18.0 kg


Please note that Amazon affiliate links in the ‘Model’ column will open in a new window for you to view updated prices and offers.

Additionally, batteries marked with an asterisk have a width slightly larger than 5.0625 inches (129 mm). Despite being labeled as Group 51/51R batteries, these batteries actually belong to the Group 22NF category and have dimensions of 9.4375 x 5.5 x 8.9375 inches (240 x 140 x 227 mm).

The nominal capacity of Group 51/51R batteries ranges from 38-66 Ah, with CCA values of 320-750, MCA values of 390-870, and RC values between 45 and 135 minutes.

It’s important to note that these numbers vary significantly due to the different types of models available – some are starting batteries, some are dual-purpose, while others are designed specifically for deep-cycle use with thick plates capable of enduring multiple deep cycle discharges.


What is the difference between Group 51 and 51R batteries?

The key difference between Group 51 and 51R batteries lies in the terminal arrangement. Group 51 batteries have the positive terminal on the left side and the negative terminal on the right, while Group 51R batteries have a reversed arrangement with the positive terminal on the right side and the negative terminal on the left.

What are the features of Group 51 and 51R batteries?

Group 51 and 51R batteries share impressive features, including robust construction, standard dimensions (approximately 9.4″ L x 5.1″ W x 8.8″ H), and left-side positive and right-side negative terminal positions. They weigh between 25 and 45 lbs and offer Cold Cranking Amps (CCA) ranging from 300 to 500, with Reserve Capacity (RC) ratings varying from 45 to 135 minutes.

Which are the recommended Group 51 battery models?

A notable model is the ACDelco Gold B24R (51 dual purpose/AGM), serving starting and deep-cycle functions. It’s crafted with a corrosion-resistant calcium alloy and features a sturdy construction to endure road vibrations. Storage in an upright position at moderate temperatures is advised to prevent self-discharge.

Can I use a Group 51R battery as a Group 51 battery?

Yes, the Group 51R battery can be utilized as a Group 51 battery by simply turning it around. This adjustment positions the positive post on the left side, resembling the standard Group 51 configuration, despite having identical dimensions.