Group 24 Battery Dimensions, Uses & LiFePO4 Upgrade Guide

If you’ve ever shopped for a car or RV battery, you’ve probably seen labels like Group 24, 24F, 27 or 35. These numbers do not tell you the chemistry or capacity of the battery. They mainly define the external size of the case and the position of the terminals, so the battery drops into your tray and the cables reach correctly.

This guide explains what a Group 24 battery really is, how big it is, where it is used, and how it compares with other nearby group sizes. We’ll also clarify an important point for EV and e-mobility users:

A Group 24 battery is usually a starter or deep-cycle battery, while an EV or e-rickshaw needs a traction / motive-power LiFePO4 pack, which is a different design.

Quick Overview: Group 24 Battery Size & Typical Specs

For quick reference, here is what most people want to know first.

Item	Typical value / range
Standard group size	BCI Group 24
Approx. dimensions (L × W × H)	10.25″ × 6.81″ × 8.88″ (260 × 173 × 225 mm)
Nominal voltage	12 V (lead-acid), 12.8 V (LiFePO4 in Group 24 case)
Typical flooded / AGM starter Ah	~ 60–85 Ah
Typical deep-cycle Ah	~ 70–100 Ah
Typical CCA range (starter types)	~ 500–850 A
Typical applications	Car starter, light truck, marine, RV house battery, UPS

Exact dimensions and ratings vary slightly by brand. Always check the manufacturer’s datasheet before replacing a battery.

BCI Group Size Basics: Where Group 24 Fits in the Battery Family

What Does “Battery Group Size” Mean?

In the automotive and marine world, batteries are often classified by BCI group size. BCI stands for Battery Council International, an organization that defines standard case sizes so manufacturers and vehicle makers can design trays and cables that match.

A group size tells you:

• Approximate length, width and height of the case
• Terminal layout and position (for example, left-positive or right-positive)
• Sometimes, typical applications (passenger car, truck, marine, RV, etc.)

What it does not guarantee:

• Exact capacity (Ah)
• Cold cranking amps (CCA)
• Internal chemistry (flooded, AGM, Gel, LiFePO4…)

That’s why two Group 24 batteries can have very different weight, capacity and performance, even though they physically fit the same tray.

Where Group 24 Sits Among Common Automotive Sizes

Group 24 is one of several medium-size 12 V case formats used in cars, light trucks, boats and RVs. Around it you will often see sizes like 24F, 27, 34 and 35.

Table – Common BCI Sizes Around Group 24

Group size	Typical L × W × H (inches)	Typical use	Notes
24	10.25 × 6.81 × 8.88	Cars, light trucks, marine, RV house	Our focus in this article
24F	10.25 × 6.81 × 9.00	Many Asian cars & small SUVs	Similar footprint to 24 but different terminal layout
27	12.06 × 6.81 × 8.88	Larger trucks, marine, RV house	Longer than 24, more room for capacity
34	10.25 × 6.81 × 7.88	Performance cars, some trucks	Same length/width as 24 but shorter case height
35	9.06 × 6.88 × 8.88	Compact cars, small crossovers	Slightly shorter and narrower than 24

Values above are typical BCI references; individual manufacturers may vary a few millimetres.

Group 24 Battery Dimensions and Key Specifications

Standard Group 24 Dimensions (Inches and Millimetres)

BCI defines Group 24 with approximate maximum exterior dimensions:

• Length: ~10.25 inches (260 mm)
• Width: ~6.81 inches (173 mm)
• Height: ~8.88 inches (225 mm)

Some batteries may be a little shorter or lower than these values, and height can be measured either to the top of the case or to the top of the terminals. When replacing a Group 24 battery, always check:

• The tray size and any height limitations (hood clearance)
• Hold-down style (top clamp, side clamp, base-rail)
• Terminal type and position (SAE posts, threaded studs, left/right positive)

Typical Capacity, CCA and Weight Ranges

Because Group 24 only defines the physical envelope, electrical specs can vary widely. The table below shows typical ranges, not hard rules.

Table – Typical Group 24 Specification Ranges

Type	Nominal voltage	Capacity range (Ah)	CCA range (A)*	Approx. weight
Flooded lead-acid starter	12 V	60–85 Ah	500–850 A	18–23 kg
AGM starter / dual-purpose	12 V	65–80 Ah	550–900 A	20–25 kg
Deep-cycle flooded / AGM	12 V	75–100 Ah	Lower CCA	20–27 kg
LiFePO4 in Group 24 footprint	12.8 V	80–120 Ah	Not rated CCA**	10–15 kg

* CCA = Cold Cranking Amps, usually specified for starter batteries.
** Many LiFePO4 makers avoid quoting CCA; they specify continuous and peak discharge currents instead.

Group 24 Starter, Deep-Cycle and Traction Batteries – What’s the Difference?

Group 24 Starter Batteries for Engine Cranking

A starter battery is designed to deliver a short, intense burst of current to crank an engine, and then immediately be recharged by the alternator. Key characteristics:

• High CCA for reliable cold starts
• Thin plates with large surface area for high current
• Intended for shallow discharges (usually less than 10–20% DOD)
• Not optimised for thousands of deep cycles

Most Group 24 batteries sold as “car batteries” belong to this category.

Group 24 Deep-Cycle and Dual-Purpose Batteries

A deep-cycle Group 24 battery is built to provide lower current for a longer time, and to tolerate deeper discharges. You’ll see these in:

• RV house battery banks
• Marine trolling motors and onboard electronics
• Small off-grid systems and backup power

Compared with starter types, deep-cycle Group 24 batteries:

• Use thicker plates and different active materials
• Have lower CCA but better cycle life at 50–80% depth of discharge
• Are often labelled with “DC”, “Deep Cycle” or “Marine/RV”

Many “dual-purpose” batteries try to combine both roles, but still share limitations of lead-acid chemistry.

Traction and Motive-Power Batteries – Different Design for Electric Drive

A traction or motive-power battery is what you find in:

• Electric scooters and motorcycles
• E-rickshaws and cargo trikes
• Low-speed electric four-wheelers and utility vehicles
• Forklifts, AGVs and industrial carts

These batteries are designed very differently:

• They must deliver continuous current to an electric motor for long periods
• They need high cycle life under deep discharge (often thousands of cycles at 60–80% DOD)
• Thermal management, BMS and pack design are critical

Saftec focuses on LiFePO4 traction batteries for two-wheelers, three-wheelers and low-speed EVs, not on traditional Group 24 starter batteries.

A Group 24 starter battery and a traction pack may both say “12 V”, but they are not interchangeable in design or purpose.

Lead-Acid vs AGM vs LiFePO4 in a Group 24 Footprint

Flooded Lead-Acid Group 24 – Pros and Limitations

Flooded lead-acid is the classic, low-cost technology:

Advantages

• Lowest upfront purchase price
• Widely available in auto parts stores worldwide
• Mature, well-understood charging systems

Limitations

• Regular maintenance (checking electrolyte, ventilation, cleaning terminals)
• Sensitive to deep discharges – cycle life drops sharply if repeatedly drained below ~50%
• Heavy for the usable energy they provide
• Sulfation and corrosion if left partially charged for long periods

AGM and Gel Group 24 – Maintenance-Free Variants

AGM (Absorbed Glass Mat) and Gel Group 24 batteries encapsulate the electrolyte, making them spill-proof and more vibration-resistant.

• No topping up of water, less gas emission
• Can often be mounted in more orientations
• Better performance under high load and partial state of charge

However, they are still lead-acid at heart:

• Similar energy density to flooded types
• Cycle life improves but is still limited compared with LiFePO4
• Higher cost than basic flooded batteries

LiFePO4 “Group 24 Size” Battery – When It Makes Sense

LiFePO4 (Lithium Iron Phosphate) batteries can also be built in a Group 24-sized case, often as a drop-in replacement for deep-cycle lead-acid. In this footprint they offer:

• Much lighter weight (often roughly half)
• Higher usable depth of discharge (typically 80–90% without harming cycle life)
• Thousands of cycles at moderate DOD
• Stable voltage during discharge
• Integrated BMS for cell balancing and protection

They are ideal when:

• You frequently cycle the battery (RV, marine, off-grid cabin, equipment power)
• Weight and space are critical
• You have a compatible charger or can adjust charging profile for LiFePO4

Chemistry Comparison in a Group 24 Form Factor

Chemistry	Usable DOD (typical)	Approx. cycle life*	Weight (typical)	Maintenance	Best suited for
Flooded lead-acid	~50%	200–400 cycles	Heaviest	Regular checks needed	Low-cost starter / occasional deep use
AGM / Gel	50–60%	400–600 cycles	Heavy	Low maintenance	Starter + moderate deep-cycle
LiFePO4	80–90%	2,000–4,000+ cycles	Lightest	Virtually none	Frequent deep-cycle, long-term storage

*Cycle life figures are broad, illustrative ranges; actual values depend on brand and operating conditions.

Common Uses of Group 24 Batteries: Cars, RVs, Boats and Beyond

Passenger Cars and Light Trucks

Many mid-size passenger cars and light trucks specify Group 24 or 24F batteries as their original starter battery. In this role, the key requirements are:

• Sufficient CCA for reliable cranking in cold weather
• Compatibility with the battery tray and hold-downs
• Correct terminal layout for the factory cables

For these vehicles, a traditional lead-acid or AGM Group 24 starter battery is usually the most straightforward choice.

Marine and RV House Battery Banks

Group 24 deep-cycle batteries are also popular in:

• Smaller boats for trolling motors and onboard electronics
• Camper vans and small RVs as part of the house battery bank
• Combined starter / house setups in lighter craft

Here, amp-hours and cycle life matter more than peak cranking amps. Upgrading from lead-acid to a LiFePO4 Group 24 deep-cycle battery can dramatically increase usable energy and reduce weight.

Off-Grid Power, Backup UPS and Specialty Equipment

Some off-grid cabins, telecom backup systems and UPS units use multiple Group 24 batteries in series or parallel strings. These applications demand:

• Reliable long-duration discharge
• Good performance at partial state of charge
• Predictable lifetime cost

For long-term deep-cycle service, LiFePO4 modules (either in Group 24 cases or in rack-mount formats) often offer a lower total cost of ownership.

Where Traction Batteries Take Over – Two- and Three-Wheeler EVs

For electric drive – scooters, e-bikes, e-rickshaws, low-speed EVs – using standalone Group 24 starter batteries is rarely optimal. Instead, manufacturers and fleet operators choose purpose-built traction battery packs:

• Configured at appropriate system voltages (e.g., 48 V, 60 V, 72 V…)
• Sized for daily range and payload
• Integrated with a dedicated BMS and motor controller

This is precisely the space where Saftec works with OEMs and fleets: designing LiFePO4 traction packs that match the mechanical space, current needs and life-cycle requirements of the vehicle platform.

Can You Swap Group 24 With Other Sizes? (24F, 27, 34, 35…)

Factors That Control Fitment: Tray, Height and Terminals

Before swapping from Group 24 to another size, you must verify:

• Tray length and width – will the new case fit safely?
• Height and hood clearance – taller batteries may contact the hood or brackets
• Hold-down style – some trays use a base-rail clamp, others a top bar
• Terminal layout – misaligned terminals can strain or reverse the cables
• Cable length – larger or more offset cases may require longer cables

A battery that “almost fits” can be a safety hazard if hold-downs no longer secure it properly.

Group 24 vs 24F – Same Footprint, Different Terminals

Group 24 and 24F share similar overall dimensions, but:

• The polarity and terminal positions are different
• Many 24F batteries have the positive post on the opposite side compared with 24

Swapping between them can only be done if the cable lengths and routing still work and polarity is maintained. In many vehicles, simply flipping between 24 and 24F is not recommended without checking a fitment guide.

Group 24 vs 27 / 34 / 35 – Longer, Shorter and Narrower Cases

• Group 27 is typically longer than 24 – it may not fit in a tray sized for 24
• Group 34 shares length and width with 24 but is shorter in height
• Group 35 is both shorter and slightly narrower than 24 – it might fit with spacers, but hold-downs may not secure it properly

Mini Table – Group 24 vs Neighbouring Sizes (Fitment Snapshot)

Group size	Relative to Group 24	Fitment comment*
24	Baseline	Designed tray size
24F	Same footprint, different posts	Only if cables and polarity still line up
27	Longer case	Needs longer tray / different hold-down
34	Same L/W, shorter height	May fit, but hold-down and clamp must match
35	Shorter & slightly narrower	Often loose in tray without adapters

*Always confirm using a vehicle-specific fitment guide.

For a detailed comparison of 24F vs 35 batteries – dimensions, CCA and when they can be interchanged – we will cover that in a dedicated guide.

How to Choose the Right Group 24 Battery?

Step 1 – Define the Job: Cranking, House Power or Electric Drive?

Ask yourself what the battery must primarily do:

• Start an engine? → You need a starter battery with adequate CCA, usually flooded or AGM.
• Run lights, appliances or electronics for hours? → Choose a deep-cycle or LiFePO4 option optimised for repeated discharge and recharge.
• Drive an electric motor for transport? → Consider a traction battery pack, not a single Group 24 starter.

Step 2 – Check the Critical Specifications

For starter applications:

• CCA (Cold Cranking Amps)
• Reserve capacity (how long it can support a smaller load)
• Compatibility with the alternator and charging system

For deep-cycle / house loads:

• Usable capacity (Wh), not just Ah
• Recommended DOD and expected cycle life
• Charging voltage and maximum charge current

For traction / motive-power:

• Required system voltage (48/60/72 V, etc.)
• Continuous and peak discharge current of the motor
• Daily energy consumption and target range
• Thermal and environmental conditions (vibration, dust, moisture)

When LiFePO4 Makes More Sense Than Traditional Group 24

LiFePO4 is worth serious consideration when:

• You cycle the battery daily or several times a week
• Weight reduction benefits fuel economy, payload or vehicle handling
• You need stable voltage for sensitive electronics or inverters
• Long-term cost of ownership matters more than lowest upfront price

In many deep-cycle and traction applications, one or more LiFePO4 modules (sometimes in Group 24-sized cases, sometimes as custom packs) can replace multiple lead-acid batteries with better lifetime performance.

Saftec Perspective: Starter vs Traction – Choosing the Right Battery Technology

Why Saftec Focuses on LiFePO4 Traction Batteries, Not Starter Batteries

At Saftec, we specialise in LiFePO4 power batteries for:

• Electric two-wheelers (delivery scooters, motorcycles)
• Three-wheelers and e-rickshaws
• Low-speed EVs, sightseeing carts, logistics platforms and specialty vehicles

These vehicles demand:

• High cycle life at deep depth of discharge
• Reliable output current for motors and controllers
• Robust BMS and pack design to handle vibration and harsh environments

Traditional Group 24 starter batteries are excellent for cranking an engine, but they are not designed for this kind of continuous, heavy-duty traction work. Rather than trying to stretch a starter format beyond its intent, Saftec designs purpose-built traction packs from the cell level upwards.

Typical Saftec Traction Battery Solutions

Depending on the vehicle platform, Saftec can provide:

• 48 V / 60 V / 72 V LiFePO4 battery packs for scooters, e-bikes and cargo trikes
• Higher-voltage packs for low-speed four-wheel vehicles and utility EVs
• Customised capacity options (Ah / kWh) for range and payload needs
• Enclosures with the right dimensions, IP rating and mounting points
• BMS with CAN/RS485 communication for integration with motor controllers and fleet monitoring

When to Use Local Starter Batteries and When to Talk to Saftec

• If you are simply replacing the starter battery in a gasoline or diesel car, your most efficient route is the local auto parts store or dealer, using a fitment guide to choose the correct Group 24 (or 24F/35, etc.).
• If you are designing, upgrading or maintaining electric drive vehicles – two-wheelers, three-wheelers, LSEVs, logistics carts – you need a traction battery, not just a Group 24 replacement.

In the second case, Saftec can help you specify:

• Voltage and capacity of the pack
• Form factor and mounting
• BMS settings and communication
• Charging strategies for long cycle life

FAQs About Group 24 Batteries and LiFePO4 Upgrades

Q1. What are the standard dimensions of a Group 24 battery?
A Group 24 battery is typically about 10.25″ long, 6.81″ wide and 8.88″ high (260 × 173 × 225 mm). Exact dimensions, especially height, can vary slightly by manufacturer, so always confirm against your battery tray and hold-down system.

Q2. Is Group 24 the same as 24F? Can I swap them?
Group 24 and 24F share a very similar footprint, but the terminal orientation is different. In some vehicles a swap is possible, but only if the cables still reach comfortably and polarity is correct. Always consult a fitment guide or a professional before interchanging them.

Q3. Can I replace a Group 24 lead-acid battery with a LiFePO4 battery?
Yes, many LiFePO4 batteries are built in a Group 24-sized case for deep-cycle use. You must ensure that your charger and charging system are compatible with LiFePO4 voltage requirements and that the battery includes a suitable BMS. For engine starting, check whether the LiFePO4 model is rated for cranking duty; not all are.

Q4. Is a Group 24 battery suitable as a traction battery for electric drive?
For experimental projects it may be possible to use Group 24 deep-cycle batteries in small electric vehicles, but for serious traction work a purpose-built LiFePO4 traction pack is strongly recommended. It will provide better cycle life, performance and safety than repurposed starter batteries.

Q5. What if I need more energy than a single Group 24 battery can provide?
You can connect multiple Group 24 batteries in series or parallel, but weight, space and cable complexity increase quickly. In many cases, a modular LiFePO4 pack or rack-mount battery with higher voltage and capacity is a more elegant and efficient solution.

Q6. How do I know whether I need a starter battery or a traction battery pack?
If the battery’s main job is cranking an engine for a few seconds, you need a starter battery in an appropriate group size. If the battery must power a motor or loads for long periods every day, you likely need a deep-cycle or traction battery, and for electric vehicles specifically, a LiFePO4 traction pack designed for your drive system. Saftec can help you choose the right type for your EV or e-mobility project.