Group 24 Batteries - Dimensions, Features, and Recommendations

BCI Group 24 batteries are mostly general-purpose batteries commonly found in large UPS systems, medical and security systems, wheelchairs, in vehicles, industrial applications, etc. They are rarely used as starting/cranking batteries - more commonly, they are used in deep cycle standby/float applications.

These mid-size batteries feature several subgroups, differing slightly in their dimensions - one must be careful which battery is required since even the slightest size differences may cause the battery not to fit its compartment.

Updated: February 14, 2023.

Intro to Group 24 Batteries

The most common BCI Group 24 battery chemistry is AGM (Absorbent Glass Mat) SLA (Sealed Lead Acid) battery, but there are other chemistries/type present as well, like gel-cell batteries, flooded batteries, and even lithium-ion batteries.

BCI Group 24 batteries feature dimensions of (L x W x H) 10.25 x 6.8125 x 8.875 inches (260 x 173 x 225 mm), but there are other subgroups present as well:

BCI Group Size	L x W x H (mm)	L x W x H (inches)	Amazon Search
24	260 x 173 x 225	10 1/4 x 6 13/16 x 8 7/8	Group 24 Battery
24F	273 x 173 x 229	10 3/4 x 6 13/16 x 9	Group 24F Battery
24H	260 x 173 x 238	10 1/4 x 6 13/16 x 9 3/8	Group 24H Battery
24R	260 x 173 x 229	10 1/4 x 6 13/16 x 9	Group 24R Battery
24T	260 x 173 x 248	10 1/4 x 6 13/16 x 9 3/4	Group 24T Battery

Note: Amazon affiliate links in the chart open in the new windows, feel free to check them.

Although these batteries are rather similar, note that BCI Group 24F is slightly longer and wider than other groups.

Despite height differences, in most cases, battery compartments have at least some spare height and if they can accommodate Group 24 battery (8 7/8 inch height), in most cases, they can accommodate even the batteries from Group 24T (9 3/4 inch height) which is 7/8 inch (0.875 inch, ~22 mm) taller than 'standard' Group 24 battery.

 Group 24 Batteries vs. Other Popular Battery Groups

The most common battery groups and their dimensions in inches and centimeters are given in the following chart:

Battery compartments that accept group 24 batteries may also accept group 34 batteries (same length and width, just one inch lower height).

Group 25/35 batteries feature the same height (8.875 inches, 22.5 cm), they are somewhat shorter (~1.2 inches, 3 cm) but are also slightly wider (0.0625 inches, 0.16 cm) - this width difference is so small that practically can be ignored.

Note: Group 25 and group 35 batteries feature the same physical dimensions and are used almost interchangeably. But, when getting group 25/35 batteries, be sure to check actual dimensions, terminal type, terminal orientation, and similar. But that is another story ...

Group 24 Batteries Comparison Chart

The following chart lists some of the most popular BCI Group 24 batteries:

Note: Amazon affiliate links ('Model' column) open in the new windows, feel free to check them for the most up-to-date prices and offers.

Again, since group 24 battery compartments may accept group 34 batteries, at least regarding the size, if You are looking for a starting Group 24 battery, be sure to check starting group 34 batteries.

Due to the slightly smaller dimensions, group 34 batteries feature a smaller 20h capacity (50-75 vs. 75-85 Ah), shorter Reserve Capacity (100-145 vs. 140-180 minutes), and are generally somewhat lighter (37 - 51 vs. 43 - 57 pounds).

Since group 24 batteries are mostly deep cycle batteries and group 34 batteries may be found as deep cycle, dual purpose, and starting batteries, people that need starting group 24 batteries should consider either dual-purpose group 24 batteries or dual purpose/starting group 34 batteries.

Group 24 Batteries as Wheelchair Batteries

Due to their dimensions and weight, lead-acid group 24 batteries are mostly used in single-battery, 12 volts wheelchair electric systems.

The endurance of such wheelchairs depends on their motors, controllers, terrain, and driving needs and habits. For example, wheelchairs with 2x150 Watt motors, may expect operating time roughly similar to the Reserve Capacity value of these batteries.

One of the best deep cycle performers in this group is VMAXTANKS SLR-85, featuring an RC value of 180 minutes - that is, 3 hours of non-stop driving at full power.

However, wheelchairs designed for outdoor use commonly have 2x250 or 2x300 watts motors, requiring 40-50 Amps of current.

Group 24 batteries can provide such currents, but as the current is increased, effective capacity is decreased, for example:

• Mighty Max ML75-12: 48.5 Amps for 1h, down to 9.6 volts (48.5 Ah),
• UPG UB12750: 42.0 Amps for 1h, down to 9.6 volts (42.0 Ah).

On the other hand, lithium group 24 batteries are at least 2x lighter than the AGM group 24 batteries, and they don't suffer from the capacity loss caused by high-discharge currents, at least not like AGM batteries.

For example, Battle Born group 24 lithium batteries feature:

• Battle Born BB1250: 50Ah capacity, 60 Amps max. continuous discharge, 100A 3s surge current, 22 lbs (9.96 kg),
• Battle Born BB1275: 75Ah capacity, 100 Amps max. continuous discharge, 200A 3s surge current, 27 lbs (12.23 kg).

As such, swapping a single AGM wheelchair battery with one lithium battery leads to decreased weight by 25-30 pounds and somewhat increased performances in terms of speed, agility, and range.

But, swapping a single AGM wheelchair battery with a pair of lithium batteries leads to somewhat decreased weight but significantly increased range.

Note: Lithium batteries can be connected in parallel only if explicitly allowed by the manufacturer. Also, they must be recharged using dedicated lithium battery chargers or advanced AGM battery chargers featuring dedicated lithium battery charging mode.

 Group 24 Batteries As Power Inverter Batteries

Group 24 batteries are often used as solar and off-the-grid batteries to provide power to 120V AC loads using DC-to-AC power inverters.

With a typical RC value of 120+ minutes, group 24 batteries can provide 25 Amps for at least 2h, which means that they can, on average, provide ~300W for 2 hours.

If such a battery powers a power inverter with an energy efficiency of 90%, then such a system can provide the following:

P_Inv = P_Bat * 0.90 = 270 Watts

So, group 24 AGM batteries, in combination with a 90% energy-efficient power inverter, can provide at least 270W 120V AC for at least 2 hours.

Since lithium batteries are more energy efficient, they can provide even more power for a longer period of time, but this depends on the battery's actual capacity since lithium group 24 batteries feature capacities in the 50-75 Ah range.

How To Charge Group 24 Batteries

Group 24 batteries can be recharged using intelligent battery chargers in the 15-20 Amps range. However, in order to avoid overstressing the batteries, a good 10 Amps battery charger can do the job very well.

For example, if the 12V 75Ah battery is discharged down to 80% DoD (20% Soc), it requires some ~60Ah of charge to be recharged completely.

A 10 Amps intelligent battery charger can recharge a such battery in 6.5-7 hours.

Note: for lithium batteries, use lithium battery chargers or AGM battery chargers that feature dedicated lithium battery charging mode (CC/CV - Constant Current/Constant Voltage). One of the most popular chargers is NOCO GENIUS10 10A 6V and 12V Smart Battery Charger (Amazon link opens in the new window), which supports charging of 6 and 12V AGM and wet/flooded lead-acid batteries and 12V lithium batteries and can be used to repair deeply discharged lead-acid batteries. After recharging the batteries, the charger switches to maintenance mode, keeping the batteries fully charged over longer period.

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Long Story Short: BCI group 24 batteries are primarily intended for deep cycle or dual-purpose applications.

Regardless if they are intended for automotive, marine, or industrial applications, these batteries can store plenty of energy.

These batteries differ in terms of chemistry, battery type, terminals, weight, starting and deep discharge performances, and in the end, price.

Note: Amazon affiliate links ('Model' column) open in the new windows, feel free to check them for the most up-to-date prices and offers.

As usual, before ordering a new group 24 battery, be sure to check the specifications of your old battery (especially the battery and battery compartment's actual size) and compare it with the batteries in the chart.

Note: whatever you do, stay safe. Even deep-cycle batteries can provide a serious energy burst and cause damage, injuries, or worse.