At a Glance: Most campers need a 12V deep cycle battery between 100 and 300 amp hours, sized to your daily power use, the type of camping you do, and your chosen battery type. The most common single-battery group sizes are Group 24, 27, and 31, while pairs of 6V GC2 batteries wired in series are the most popular upgrade.
A dead battery is the fastest way to ruin a camping trip. The right deep cycle battery powers your lights, water pump, fridge, and electronic devices for days at a time, even off-grid. Here is how to size the right battery for your camper.
Deep Cycle vs. Starting Battery
A starting battery delivers a quick burst to crank an engine. A deep cycle battery is built for a steady draw over a long period, with hundreds of discharge cycles built into its design. That makes deep-cycle the right choice for camper applications, where your battery runs lights, the water pump, a vent fan, the furnace blower, USB outlets, and inverter loads for hours on end.
Towed campers (pop-ups, truck campers, travel trailers, and fifth wheels) only need a deep cycle house battery because there is no engine to start. Motorized RVs use both: a chassis starting battery for the engine and one or more deep-cycle house batteries for the living space.
Common Deep Cycle Battery Sizes for Campers
In North America, BCI group sizes describe the physical dimensions and terminal layout of a battery. The group size determines what fits your battery box, while the amp-hour rating tells you how much power it stores. These are the sizes that fit most campers:
- Group 24 (roughly 70 to 85 Ah): Fits most travel trailer tongue boxes and small campers.
- Group 27 (roughly 85 to 105 Ah): A common single-battery upgrade with more capacity in a similar footprint.
- Group 31 (roughly 100 to 125 Ah): The largest single 12V that fits a standard tray.
- 6V GC2 pair (roughly 200 to 250 Ah at 12V): Two 6V deep cycle batteries wired in series fit in the same space as one Group 24 and deliver far more usable capacity. The most popular upgrade for serious RV owners.
- 4D and 8D (roughly 200 to 260 Ah each): Big batteries for fifth wheels and motorhomes with large compartments and bigger battery banks.
Fullriver offers AGM batteries in every one of these sizes across our Full Force, EGL, and DC Series lineups, so you can match capacity to your battery box without changing mounting hardware.
How to Calculate the Right Battery Size for Your Camper
Sizing comes down to four steps:
Step 1: List your loads – Write down every device on your camper’s 12V electrical system: LED lights, water pump, fridge, vent fan, furnace blower, TV, USB charging, and any inverter loads.
Step 2: Estimate daily watt-hours – Multiply each device’s wattage by hours of daily use. Add them up. A typical weekend camper uses 400 to 800 watt-hours per day; a full-time setup with a 12V fridge and inverter loads can use 1,500 to 3,000 watt-hours per day.
Step 3: Convert to amp-hour – Divide daily watt hours by your nominal battery voltage (12V for most campers): 800 watt hours ÷ 12V = about 67 amp hours per day.
Step 4: Account for depth of discharge – A premium AGM battery delivers strong, reliable performance when discharge cycles stay above 50%. To get the rated capacity you need, double your daily Ah figure and multiply by your days off-grid: 67 Ah × 2 × 2 days = about 268 Ah of rated capacity for a two-night dry camping trip.
This is the same logic from our amp hours guide, where rated capacity and usable capacity work together to determine real-world runtime.
Battery Size Recommendations by Camper Type
The right size depends on how you camp. Here is what works for each common camper category.
- Pop-up or teardrop camper: Light loads, weekend use, often a single battery box on the tongue. A single Group 24 12V deep cycle battery in the 70 to 100 Ah range covers it. The FFD85-12 or DC85-12 AGM (12V, 85 Ah, Group 24) is an excellent choice.
- Truck camper or small travel trailer: Mid-range loads, occasional dry camping. A single Group 31 (100 to 125 Ah) handles most setups. The FFD115-12, DC115-12, or premium EGL100-12 (12V, Group 31) all fit common camper trays.
- Mid-size travel trailer or fifth wheel: Multiple appliances, weekend or week-long dry camping. This is where the 6V GC2 pair upgrade shines. Two FFD200-6 or FFD224-6 wired in series give you 200 to 224 Ah at 12V. For longer battery life, step up to the DC224-6 or premium EGL220-6 pair (220 to 224 Ah at 12V).
- Large fifth wheel or motorhome with heavy loads: Full-timer setups running a residential fridge, inverter, and frequent boondocking need 300 to 600+ Ah of battery bank. Two FFD260-12 or DC260-12 (12V, 260 Ah, 8D) batteries in parallel, or larger banks of 6V GC2 batteries wired in series-parallel, deliver consistent power for an extended period off shore power.
Why AGM Is the Best Choice for Camper Batteries
AGM is the smart default for most recreational vehicles and RV applications. The sealed absorbent glass mat design contains no spillable sulfuric acid and delivers strong reserve capacity for accessory loads, mounts in any orientation, and needs no water level checks like a traditional lead-acid battery requires. Strong vibration resistance and deep cycling capability handle rough roads and demanding loads, and any quality battery charger built for AGM keeps the system topped off, no special BMS or proprietary charger required. Compared to a flooded battery, AGM gives you longer battery life, more reliable performance, and zero maintenance. Compared to a lithium battery, AGM offers proven reliability and far better value, without the higher upfront cost of lithium iron phosphate or lithium-ion battery systems.
Fullriver has manufactured premium AGMs since 1995, with one of the lowest warranty rates in the industry. That track record is why so many full-time and weekend RV owners trust Fullriver as a dependable power source for everything from a single Group 24 battery to a 600 Ah battery bank.
Tips to Make Your Camper Battery Last Longer
A few simple habits protect your investment and extend battery life:
- Avoid deep discharge below 50% on AGM whenever possible.
- Recharge with a multi-stage AGM-compatible charger after every trip.
- Pair with a solar panel and a quality controller to maintain charge during long periods of storage.
- Disconnect the battery when storing your camper for extended periods to prevent parasitic drain from clocks, propane detectors, and other always-on devices.
- Keep terminals clean and connections tight on every battery in your bank.
Find the Right Fullriver Battery for Your Camper
Sizing your battery is half the work; choosing one built to deliver that capacity reliably is the other half. Use our Battery Finder to match a Fullriver deep cycle battery to your camper, browse the full Full Force, EGL, and DC Series lineup on our RV battery page, or find a local dealer to pick up a new battery before your next trip.
Frequently Asked Questions
How many amp-hours do I need for a weekend camper trip?
Most weekend campers need between 100 and 200 amp hours of total battery capacity, depending on loads. A pop-up with LED lights and a water pump may only need 70 to 100 Ah, while a small travel trailer running a 12V fridge and fan typically needs 150 to 200 Ah for two nights off-grid.
Can I replace one 12V battery with two 6V batteries in my camper?
Yes. Wiring two 6V GC2 deep-cycle batteries in series creates a 12V system with significantly more amp hours than a single Group 24 or 27 12V battery, and the pair fits most camper battery boxes. This is one of the most popular upgrades for RV owners who run inverters or boondock often.
What is the difference between Group 24, 27, and 31 batteries?
The difference is mainly physical size and capacity. Group 24 batteries are the smallest (about 70 to 85 Ah), Group 27 is mid-size (about 85 to 105 Ah), and Group 31 is the largest single 12V (about 100 to 125 Ah). Match the group size to your battery box, then pick the highest capacity that fits.
How long will a 100 Ah deep-cycle battery run my camper?
It depends on your loads. A 12V 100 Ah AGM battery holds about 1,200 watt hours and delivers around 50 usable amp hours when discharged at 50%. For a small camper running LED lights, a water pump, and a small fan, that is typically one to two nights of dry camping per battery.
