What Is a Group 24 Battery? A Plain Guide to Group 24 Deep Cycle RV Batteries
You pull the old house battery out of your RV's tongue box and spot the number 24 on its label. At the store, though, several batteries claim to fit the same space. Which one should you buy? A group 24 deep cycle battery follows a particular case size and terminal layout, but that number doesn't tell you how much energy it stores or how long it'll last. Here's how to compare battery types, estimate usable power, check the fit, and choose a battery that works with your RV's charging system.
What Is a Group 24 Battery?
Group 24 is a battery size code established by Battery Council International (BCI). It describes the battery's general case dimensions and terminal arrangement, helping you find one that fits your RV's battery tray and cables. The code doesn't specify the battery chemistry, capacity, weight, or intended use.
What the group number tells you
The number gives you a starting point when replacing an RV house battery. You'll still need to check a few details before buying.
Case size: Length, width, and height determine whether the battery fits the tray and clears its cover.
Terminal layout: The posts must match your cables, including their positive and negative positions.
Chemistry and capacity: The group number doesn't tell you whether the battery is flooded lead-acid, AGM, or lithium, or how many amp-hours it provides.
Battery purpose: A group 24 battery might be designed for deep cycling, engine starting, or both. Check the label.
You may also see a suffix, such as 24F, on a battery label. These codes can indicate a variation in size or terminal arrangement. Match the full code on your existing battery or in your RV manual rather than relying on the number alone.
Real case sizes vary by maker
Group 24 batteries can vary slightly in size, so don't assume every model will fit your existing tray. For example, Trojan lists its 12V 24TMX flooded lead-acid battery at 10.92 × 6.62 × 9.25 inches and 47 pounds. Confirm the group designation in the manufacturer's linked datasheet before treating that model as a verified Group 24 example.
Example battery (maker page) | Chemistry | Length x width x height | Weight |
Trojan 24TMX (12V) | Flooded lead-acid | 10.92 x 6.62 x 9.25 in (277 x 168 x 235 mm) | 47 lb (21 kg) |
LiTime 12V 100Ah Group 24 | LiFePO4 | 10.23 x 6.61 x 8.22 in (260 x 168 x 209 mm) | Approx. 21 lb (9.53 kg) |
Measure the tray, hold-down, and space beneath the lid before ordering. Also check how far the cables reach. Trojan offers the 24TMX with several terminal options, including automotive posts, wingnut terminals, and small L-terminals. The right case size won't help if the posts don't match your cables. If your battery label also says deep cycle, that describes its intended job. A deep cycle battery is designed to supply power over an extended period and handle repeated discharging and recharging. A starting battery, by contrast, delivers a strong burst of current to crank an engine. Once the size fits, the next decision is which battery chemistry makes sense for your RV.
Group 24 Deep Cycle Battery Types: Flooded, AGM and Lithium
A group 24 case can hold flooded lead-acid, AGM, or lithium iron phosphate (LiFePO4) cells. Each type has different maintenance needs, usable capacity, weight, and charging requirements. The right choice depends on your budget, travel habits, climate, and RV's existing electrical system.
How the three battery types compare
Point | Flooded lead-acid | AGM | LiFePO4 (lithium) |
Maintenance | Add distilled water after full charge (Trojan) | Sealed AGM batteries need no watering, but ventilation requirements still apply. Trojan’s AGM guidance calls for charging in a well-ventilated area; follow the exact battery model’s installation instructions. | No watering |
How deep to discharge | Trojan recommends 20 to 50% of rated capacity for best life, though the battery can be cycled to 80% | Use the selected AGM model’s recommended discharge limit and cycle-life curve. There is no single depth-of-discharge limit that applies to every AGM battery. | Maker ratings vary; LiTime lists 4,000+ cycles at 100% DoD for its group 24 |
Cold weather | A discharged battery can freeze; at 40% charge, about 16°F (Trojan) | Follow the selected model’s temperature limits and storage instructions. Trojan’s AGM guidance says to fully charge batteries before storage and never charge a frozen battery. | Should not be charged below about 25°F unless it has internal heating (Battle Born) |
Engine starting | Deep cycle is not a starting battery (Trojan) | Check the label: deep cycle, starting, or dual-purpose | The LiTime group 24 lithium is "NOT suitable for starting" |
Flooded lead-acid batteries
Flooded batteries are a familiar choice for RV house power. They can work well when you maintain them and follow the manufacturer's charging instructions. Trojan recommends keeping discharge around 20% to 50% of rated capacity for the best service life, though its batteries may support deeper cycling under specified conditions. These batteries need more attention than sealed designs. Trojan recommends checking electrolyte levels and adding distilled water as directed after charging. Charge flooded batteries in a well-ventilated area, and keep sparks and flames away.
AGM batteries
Absorbent glass mat (AGM) batteries are sealed lead-acid batteries that don't require routine watering. That can make them easier to manage in an RV, but you still need to follow the manufacturer's instructions for charging, ventilation, temperature, and discharge depth. Don't assume every AGM battery is suitable for engine starting. Check whether the specific model is designed for deep-cycle use, starting, or both.
LiFePO4 lithium batteries
LiFePO4 batteries generally weigh less than comparable lead-acid models and offer more usable energy. The LiTime 12V 100Ah Group 24 battery lists 1,280Wh and a rated 4,000+ cycles at 100% discharge, though actual life varies. Some lithium batteries also can't be charged below about 25°F without internal heating. Before switching from lead-acid, have an RV technician check that your converter, solar controller, and alternator charging system support lithium. Compare options for the best lithium battery for your RV and review the charging requirements before buying.
How Much Power Does a Group 24 RV Battery Really Give You?
Amp-hours (Ah) describe battery capacity, but the number alone doesn't tell you how much energy a battery stores. You also need its voltage. Multiply amp-hours by volts to estimate watt-hours, then account for how much energy you can use without exceeding the battery's recommended discharge limit.
Same job, same units
The following figures use manufacturer-listed capacities. The usable-energy estimates for lead-acid and portable power stations use different assumptions, so they aren't direct measurements under identical conditions.
Power source | Rated figures (maker) | Calculation | Energy you can plan on (estimate) |
Trojan 24TMX flooded | 85Ah at the 20-hour rate, 12V | 85Ah x 12V = 1,020Wh; x 50% (Trojan's upper recommended discharge) | About 510Wh of DC energy |
LiTime 12V 100Ah Group 24 | 1,280Wh | Maker's stated energy | Up to 1,280Wh DC by the maker's rating; Real use depends on BMS, temperature, and loads |
EcoFlow DELTA 3 Classic (1024Wh) | 1,024Wh (51.2V, 20Ah) | 1,024Wh x 0.85 | About 870Wh at the outlets |
EcoFlow DELTA 3 Max (2048Wh) | 2,048Wh | 2,048Wh x 0.85 | About 1,741Wh at the outlets |
The 0.85 factor is an assumed conversion efficiency for the EcoFlow estimates, not a guaranteed result. The lead-acid and lithium battery figures represent stored DC energy before an inverter. The EcoFlow figures estimate energy available at the outlets after conversion losses. Notice the difference between amp-hours and watt-hours. The EcoFlow DELTA 3 Classic has a 20Ah rating at 51.2V, yet stores about 1,024Wh. That's roughly the same nominal energy as an 85Ah battery at 12V, which stores about 1,020Wh. Comparing amp-hours without checking voltage can lead to the wrong conclusion.
When a separate power source makes sense
Your RV's group 24 battery may already handle lights, water pumps, and other 12V house loads. If you want to run camp gear such as a laptop, phone charger, or portable refrigerator, a power station can provide separate AC outlets without changing the RV's 12V wiring. Here are two examples using assumed appliance loads. Actual runtime depends on the devices you use and their power draw.
Setup | Example load | Calculation | Estimate |
EcoFlow DELTA 3 Classic | LED lamp 20W + laptop 45W + phone charging 15W = 80W (example values) | 1,024Wh x 0.85 / 80W | About 10.9 hours |
EcoFlow DELTA 3 Max | The same 80W + a portable fridge averaging 45W = 125W (example values) | 2,048Wh x 0.85 / 125W | About 13.9 hours |
These are planning estimates, not runtime guarantees. Use the wattage listed on your own devices, and account for how often a compressor refrigerator cycles on and off. Neither power station replaces the group 24 battery in the RV's battery tray or the battery used to start the engine. Keep the RV's 12V system on its own properly matched battery, charger, and protection. Two EcoFlow DELTA 3 models cover separate camp loads, depending on whether a portable fridge is part of the plan.
If the EcoFlow DELTA 3 Classic doesn't provide enough capacity for your camp setup, the EcoFlow DELTA 3 Max offers more output and twice the battery capacity. It's a better fit when you want to run a compatible portable fridge alongside smaller devices.
The EcoFlow DELTA 3 Classic suits lights, phones, and a laptop, while the EcoFlow DELTA 3 Max adds capacity for a compatible portable fridge. Neither replaces your RV's group 24 battery or connects to its 12V system. To understand battery capacity, read our guide to what Ah means. With a separate power source covered, let’s look at how to choose and fit the right group 24 battery for your RV.
How to Choose and Fit a Group 24 Deep Cycle RV Battery
The right group 24 deep cycle RV battery should fit the tray, match the existing cables, and work with your charging system. A few checks before you buy can prevent an expensive return or an installation problem.
Check these details before buying
Read the existing label and RV manual. Confirm the group code, voltage, terminal type, and positive/negative positions.
Measure the battery space. Check the tray, hold-down, and lid clearance against the new battery's spec sheet.
Choose the right battery purpose. Deep-cycle batteries serve house loads; starting batteries crank the engine. A dual-purpose battery is a compromise between those jobs.
Compare weight. The Trojan 24TMX weighs 47 lb. Lithium models are often lighter, but check the exact specifications.
Check the charging system. Your converter, solar controller, and alternator charging must support the battery chemistry.
Follow flooded-battery precautions. Charge in a ventilated area and keep flames and sparks away.
Don't change cable sizes, fuse ratings, or charger settings based on guesswork. Have an RV technician confirm any changes, especially when switching from lead-acid to lithium. If you need help with charging basics, see the guide on charging a deep cycle battery.
How Long Does a Group 24 Deep Cycle Battery Last?
There's no single lifespan that applies to every group 24 battery. Chemistry, discharge depth, temperature, charging habits, and storage all affect how long it remains useful. Follow the battery maker's guidance rather than relying on a general number of years.
Habits that help protect battery life
A few simple habits can help your RV battery last longer, though the right approach depends on its chemistry and storage conditions. Follow the manufacturer's guidance on charging, temperature, and discharge depth, and keep these tips in mind:
Avoid deep discharges on lead-acid batteries. Trojan recommends using about 20% to 50% of rated capacity for the best life.
Keep lead-acid batteries charged during storage. Leaving one partly discharged can cause sulfation and reduce capacity.
Watch cold-weather storage. Trojan notes that a battery at 40% charge can freeze at about 16°F.
Limit heat exposure. Trojan says temperatures above 80°F can increase capacity while shortening battery life.
Follow lithium temperature limits. Some LiFePO4 batteries shouldn't be charged below about 25°F unless they have internal heating. Check the exact model's manual.
Disconnect parasitic loads when storing. Keep the battery charged according to its manufacturer's instructions.
Battery life also depends on usage and upkeep. For more guidance, see our article on how long RV batteries last.
Conclusion
Group 24 tells you about battery fit, not the energy available for your trip. Before buying, measure the tray, match the terminal layout, compare usable watt-hours, and make sure your converter and other charging sources support the battery chemistry. If you also need separate power for camp gear, consider the EcoFlow DELTA 3 Classic for lights, phones, and a laptop, or the EcoFlow DELTA 3 Max if a compatible portable fridge is part of your setup.
FAQs
What is a group 24 battery?
A group 24 battery follows a BCI case-size and terminal-layout designation. The code helps you check fit, but it doesn't tell you the chemistry, capacity, or whether the battery is designed for deep-cycle or starting use.
How much does a group 24 battery weigh?
Weight depends on the model and chemistry. The flooded Trojan 24TMX weighs 47 lb. Lithium group 24 batteries are often lighter, but check the manufacturer's specification sheet before buying.
Can I use a group 24 deep cycle battery to start my engine?
Not unless the battery is rated for that purpose. Deep-cycle batteries are designed for sustained power delivery, while starting batteries supply a short burst of high current. Check your vehicle or RV manual and the battery's label.
How deeply can I discharge a group 24 deep cycle battery?
For flooded lead-acid batteries, Trojan recommends using about 20% to 50% of rated capacity for the best life. Lithium batteries may allow deeper discharge, but their limits depend on the model. Follow the manufacturer's guidance.
Can a portable power station replace my group 24 RV battery?
No. A portable power station doesn't fit the RV battery tray or replace the battery connected to its 12V system. It can run separate devices plugged into its outlets, such as a laptop, lights, or a compatible portable fridge, for a limited time.
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