Best BCI Group 24 Batteries

BCI Group 24 batteries are very popular automotive, industry, and marine batteries, commonly used as starting, deep cycle, and general-purpose batteries.

While they feature standard dimensions, these batteries differ internally significantly, offering the users different characteristics regarding nominal capacity, starting features, number of cycles, and similar.

BCI group 24 batteries include several sub-models, each differing slightly in size from the main 'group 24 battery':

When looking for a new BCI group 24 battery, be sure to check the actual size of your old group 24 battery, to check the available space of your battery compartment, and before purchasing a new battery, check its actual size in inches/mm - some manufacturers may label their battery as, for example, group 24 battery, but to have one or more sides of battery slightly larger than it should.

The following chart compares group 24 battery dimensions with other popular BCI battery groups:

As one can see, group 24 battery dimensions are (L x W x H) 10.25 x 6.8125 x 8.875 inches (26 x 17.3 x 22.5 cm) - that means that any group 24 battery should fit the battery compartment (or battery box) that has such internal dimensions.

Group 24 Battery vs Group 34 Battery

Group 34 batteries are an even more popular battery group, especially in the automotive industry, and are even more common on the market than group 24 batteries.

Their dimensions are (L x W x H):

- Group 24 battery: 10.25 x 6.8125 x 8.875 inches (26 x 17.3 x 22.5 cm),

- Group 34 battery: 10.25 x 6.8125 x 7.875 inches (26 x 17.3 x 20 cm).

The only difference between group 24 and group 34 batteries is that group 24 batteries are one inch (2.54 cm) taller than group 34 batteries and thus feature larger volume, leading to larger capacity, stronger starting currents, longer Reserve capacity (RC), etc.

While replacing the battery of one battery group with another battery from another battery group is not generally recommended, it is possible in this case, but there are so many things to think about like new battery actual dimensions and its actual performances (including charging current!).

Most Popular Group 24 Batteries

The following chart lists the most popular BIC group 24 batteries:

Group 24 batteries are mostly deep-cycle batteries intended for cyclic and standby use in off-the-grid, medical, security, solar, and similar applications.

However, some models (for example, NorthStar NSB-AGM24F) are made as dual-purpose batteries having good both starting and deep cycle features.

On average, group 24 batteries feature nominal capacity between 75 and 85 Ah, Reserve Capacity (RC) of 140-180 minutes and they weigh 43 - 57 pounds (~19.5 - 25.8 kg).

Starting values (Cold Cranking Amps - CCA, Marine Cranking Amps - MCA), vary depending on the battery intended use - some manufacturers don't even state CCA/MCA values for their deep cycle batteries (so, don't use them as starting/cranking batteries at all).

For comparison purposes, the following chart lists the most popular group 34 batteries.

Note: Group 24 batteries are one inch (2.54 cm) taller than group 34 batteries, having greater volume and mass.

Group 34 batteries are very often used in cars, trucks, boats, and in the industry as starting/cranking batteries. Thus, they are mostly designed as starting or dual-purpose batteries, with only very few group 34 batteries being manufactures as deep cycle batteries.

On average, group 34 batteries feature nominal capacity of 50-75 Ah (vs group 24 75-85 Ah), Reserve Capacity (RC) of 100-145 minutes (vs group 24 140-180 minutes) and they weigh 37 - 51 pounds (16.8 - 23.1 kg - vs group 24 43-57 pounds/19.5-25.8 kg).

With so many starting and dual purpose group 34 batteries, and only a few dual-purpose group 24 batteries, the best group 34 batteries are better starting batteries than the best group 24 batteries, although the difference isn't large (CCA 880 Amps vs 840 Amps, MCA 1050 Amps vs 1000 Amps).

This comparison just shows the importance of checking actual data of all the batteries, not just car, marine, or industrial batteries.

How to Charge Group 24 Batteries

When the battery is permanently placed inside the car, truck, or any similar vehicle, boat, or industrial machine featuring a built-in alternator, let the alternator keep the battery charged.

If the group 24 battery is being used as a stand-alone battery, the best way to charge it is by using smart battery chargers, dimensioned according to the actual battery capacity - for 75-85 Ah batteries, 10-15 Amps battery chargers are recommended.

Smart battery chargers have many advantages over simple battery chargers, including:

- before actual charging, the user may set the battery type (wet/flooded, AGM, Gel, Calcium, Lithium, etc.), battery use (cycle, float), and connect battery thermometer for temperature compensation,

- before actual charging, smart battery chargers analyze the battery condition, and if the battery is over-discharge, they can start the recovery process automatically,

- smart battery chargers charge the battery in different phases according to the battery condition (soft charge, bulk charge, normalization),

- when the battery is fully charged and the cells are normalized, the battery charger switches itself in the maintenance mode, keeping the battery fully charged.

Of course, different models of such chargers may have other features as well, but these are the most common ones.

Common Group 24 Battery Uses

Group 24 batteries are used in various applications, including:

- Vehicle/Industry Battery: dual-purpose group 24 batteries are used as starting batteries in vehicles having other larger loads like pumps, winches, lights, and similar. In such applications, these batteries are regularly drained down to 50% DoD (or even more) and are recharged using onboard alternators.

- Trolling Motor Batteries: with RC values in 140-180 minutes range, group 24 batteries are able to power 50 Amps trolling motor for an hour easily and when the motors are not pushed to the maximum, they can power them up to two hours, even slightly more.

- Sump Pump Backup Battery: actual operating time depends on the sump pump motor power which ranges from 250 watts to more than 1 kW. For such systems, especially for stronger motors, dual-purpose group 24 batteries are recommended.

- Solar Battery: deep cycle group 24 battery may be charged fully using 100 W solar panel during the day, even when conditions are not perfect (semi-cloudy weather). During the night, the batteries are able to provide 30-40 watts during the period of 7-8 hours (actual numbers differ depending on the battery model).

There are many other potential uses where these batteries may be rather useful, like electric vehicles, security systems, medical systems, backup power systems, etc.

When picking a new battery, be sure to check its electric features, actual physical dimensions and compare it with your old battery - choose according to your needs and the intended use.