Caravan leisure batteries are typically 12-volt deep-cycle units. The “size” you’ll see refers to two things: the physical group size (for example Group 24 or Group 27) and the energy capacity in amp-hours (Ah). In practice, many caravanners use Group 24 or Group 27 lead-acid batteries with roughly 70–120 Ah, while lithium options can offer similar footprints with higher usable capacity.
Common physical sizes used in caravans
The following group sizes are the most commonly fitted to caravan leisure batteries. The exact capacity and weight vary by manufacturer and chemistry, but the group size gives you the footprint to fit in the battery compartment.
- Group 24: Typical lead-acid (AGM/GEL) capacity around 70–105 Ah; commonly used in mid-size caravans. Heavier than lithium equivalents for the same usable energy.
- Group 27: Typical lead-acid (AGM/GEL) capacity around 90–120 Ah; larger footprint with higher energy potential, suited to higher power use.
- Group 31: Typical lead-acid (AGM/GEL) capacity around 95–150 Ah; big footprint but popular in larger caravans or when higher storage is needed.
- Lithium (LiFePO4) options: Batteries in similar footprints can offer 100–200+ Ah usable capacity with much lower weight; they fit many Group 24–27–31-sized spaces but require compatible charging and a battery management system.
Choosing the right size depends on your space, your energy needs, and whether you prioritize cost, weight, or longevity. In practice, most caravanners pick a Group 24 or Group 27 for typical use, with lithium as a premium option for higher efficiency and lighter weight.
How to choose the right size for your caravan
To pick a battery size that fits your caravan and lifestyle, consider your daily energy needs and charging options. The following guidelines help you decide.
- Estimate your daily energy usage by listing all devices (lights, fridge, water pump, TV, chargers, etc.) and their run times.
- Convert usage into amp-hours (Ah) by summing each device’s current (A) multiplied by hours used per day.
- Apply depth-of-discharge (DoD) guidelines: for lead‑acid batteries, plan for about 50% DoD to maximize life; for lithium (LiFePO4), you can typically use 80–100% DoD.
- Choose a total battery capacity that leaves a comfortable buffer for aging and unexpected extra usage (often 20–30% extra on top of your calculated Ah).
- Factor in charging availability: mains charging, solar, and vehicle alternator charging should all be compatible with the chosen chemistry.
- Check physical fit and weight in your caravan’s storage area, and ensure ventilation for flooded lead‑acid types.
- Decide on chemistry based on long-term needs and budget: lead‑acid is cheaper upfront; lithium offers higher usable capacity and longevity but at higher upfront cost.
By following these steps, you’ll select a caravan battery size that balances space, energy needs, and budget, while also accommodating future changes in usage or gear.
Chemistry options: lead-acid versus lithium
Lead-acid (AGM/GEL)
Pros: Generally lower upfront cost, simple maintenance, widely available replacement options, good reliability. Cons: Heavier, lower usable capacity due to DoD limits, shorter cycle life, and slower charging compared with lithium.
Lithium (LiFePO4)
Pros: Higher usable capacity in the same footprint, lighter weight, much longer cycle life, faster and more flexible charging, deep DoD (often 80–100%). Cons: Higher upfront cost and typically requires a compatible battery management system and charger.
Practical buying and maintenance tips
To ensure you get the right battery and keep it performing well, consider these practical tips when shopping and after installation.
- Match chargers and regulators to your battery chemistry (lead-acid vs LiFePO4) to prevent overcharging or excessive voltage.
- For lead-acid, avoid regularly discharging below 50% to maximize life; for lithium, you can typically use a higher DoD but still follow manufacturer guidelines.
- Keep terminals clean and tight; use anti-corrosion protectant on connections.
- If using flooded lead-acid, check electrolyte levels and top up with distilled water as needed.
- Consider a battery monitor or energy management system to track state of charge and usage.
- Incorporate solar or alternator charging to maintain charge during trips and prevent deep discharges.
Careful selection and regular maintenance will extend the life of your caravan battery and ensure you have reliable power whenever you stop.
Summary
Most caravanners operate a 12-volt leisure battery in a common group size such as Group 24 or Group 27, with capacities typically in the 70–120 Ah range for lead‑acid types. Lithium options offer higher usable capacity (and lighter weight) in similar footprints but at a higher upfront cost. To choose the right size, assess daily energy needs, DoD guidelines, and charging options, while ensuring the battery fits your caravan’s space and weight limits. With proper care and the right charging setup, your caravan will have dependable power for days on the road or off-grid camping.