The Complete Buyers Guide To Caravan Battery Systems

Your house battery is the heart of your caravan’s 12V system. Everything that runs when you’re not plugged into mains power draws from it: lights, the water pump, USB charging, your fridge, the range hood fan, and any 12V accessories. The battery’s capacity determines how long you can camp independently, and choosing the right battery system is probably the most impactful gear decision you’ll make for off-grid travel.

This guide covers the battery types available, how to work out what capacity you need, and specific product recommendations at every price point.

Battery Types Explained

AGM (Absorbed Glass Mat)

AGM batteries are the standard fitment in most new caravans. They’re sealed lead-acid batteries that use fibreglass mats to absorb the electrolyte, making them maintenance-free and safe to mount inside the van. AGMs are affordable, widely available, and well-understood technology.

The critical limitation: AGMs should not be discharged below 50% state of charge. Going deeper shortens their lifespan dramatically. A 100Ah AGM battery effectively gives you 50Ah of usable capacity. Typical lifespan is 300 to 500 cycles (roughly 2 to 4 years of regular use). Weight is significant: a 100Ah AGM weighs around 28 to 32kg.

Price: $200 to $400 for a quality 100Ah deep-cycle AGM.

Lithium Iron Phosphate (LiFePO4)

Lithium batteries have become the go-to upgrade for serious Big Lappers, and the price drop over the last few years has made them accessible to a much wider audience. LiFePO4 is the specific lithium chemistry used in caravans; it’s stable, safe, and doesn’t suffer from the thermal runaway issues of other lithium chemistries.

The advantages are substantial. You can safely discharge to 80 to 100% of rated capacity (a 100Ah lithium gives you 80 to 100Ah of usable power, compared to 50Ah from an AGM). They last 2,000 to 5,000 cycles (roughly 7 to 15 years). They weigh about a third of an equivalent AGM. They charge significantly faster. And they maintain voltage more consistently as they discharge, meaning your appliances run better for longer.

The downside is cost. A quality 100Ah lithium battery costs $800 to $1,500, roughly three to four times an equivalent AGM. However, when you factor in the doubled usable capacity and five-times-longer lifespan, the cost per usable amp-hour over the battery’s life is actually lower than AGM.

Price: $800 to $1,500 for a quality 100Ah LiFePO4.

Gel (Gel Cell)

Gel batteries use a gelled electrolyte and are sometimes found in older caravans. They’re more tolerant of deep discharge than standard flooded lead-acid batteries but less so than AGM. They charge slowly, are sensitive to overcharging, and offer no meaningful advantage over AGM for caravan use. If your van has gel batteries, they’ll work, but when replacement time comes, upgrade to AGM or lithium.

How To Size Your Battery System

The right battery size depends on two things: how much power you use daily and how long you want to go between charges (from solar, driving, or plugging in).

Step 1: Calculate your daily draw. List everything that runs off 12V and estimate daily usage. A typical couple free camping might use:

LED lights (5 hours): 5 to 10Ah. Water pump (intermittent use): 2 to 3Ah. 12V fridge (24 hours): 30 to 50Ah. Phone/tablet charging: 3 to 5Ah. Range hood fan: 1 to 2Ah. TV (2 hours): 5 to 10Ah. Total: roughly 50 to 80Ah per day.

Step 2: Factor in your charging sources. If you have 300W of solar and get 5 to 6 hours of good sun, that generates roughly 75 to 100Ah per day. In theory, this replaces your daily usage. In practice, cloudy days, shade, and panel efficiency losses mean you’ll generate less. Budget for solar producing 60 to 70% of its theoretical maximum.

Step 3: Size for your worst case. If you want to survive a cloudy day without running out, your usable battery capacity should be at least 1.5 times your daily draw. For 70Ah daily draw, that’s around 105Ah usable. In AGM terms, that means a 200Ah bank (50% usable = 100Ah). In lithium terms, a 120 to 150Ah bank covers it comfortably.

Charging: How Batteries Get Filled

Your battery is only useful if you can recharge it. Most caravan battery systems have three charging sources:

Solar: Panels on the roof or portable panels connected to a solar charge controller (MPPT or PWM). Solar is your primary charging source when free camping. MPPT controllers are more efficient than PWM, particularly in lower light conditions, and are worth the extra cost for any system over 200W.

DC-DC charger: Connected to your tow vehicle’s alternator, this charges your caravan battery while you’re driving. Modern vehicles with smart alternators require a DC-DC charger (rather than a direct connection) to charge properly. A quality DC-DC charger can push 20 to 40 amps into your house battery while driving, which means a few hours of driving can significantly top up your batteries.

240V charger: When plugged into mains power at a caravan park, your onboard 240V charger tops up the house battery. Most stock chargers are basic and slow (5 to 15 amps). An upgraded charger (20 to 40 amps) gets your batteries to full much faster, which matters when you’re only spending one night at a park between free camping stints.

All three sources need to be compatible with your battery chemistry. This is particularly important when upgrading from AGM to lithium, as each charging source needs a lithium-compatible charge profile.

Product Recommendations

AGM Batteries

Century C12-105DA (105Ah): The most commonly recommended AGM for caravans in Australia. Made by Century (a local brand), it’s designed for deep-cycle applications, handles repeated cycling well, and has a solid warranty. Widely available at battery retailers and auto shops. Around $280 to $350.

Exide Stowaway (120Ah): Another Australian favourite with a slightly higher capacity. Good performance, reliable, and well-supported. Around $320 to $400.

Giant Power 120Ah AGM: A budget-friendly option available through Caravan RV Camping. Decent performance for the price. Around $220 to $280.

Lithium Batteries

Enerdrive ePOWER B-TEC (100Ah / 200Ah): The premium Australian choice. Built-in battery management system (BMS), Bluetooth monitoring, and designed specifically for Australian caravan and marine use. Excellent support and warranty (7 years). The 100Ah unit weighs just 12.8kg compared to 30kg+ for an equivalent AGM. Around $1,200 to $1,500 for 100Ah, $2,200 to $2,800 for 200Ah.

Victron Smart LiFePO4 (100Ah / 200Ah): A globally respected brand with excellent build quality and Bluetooth monitoring through the Victron app. Integrates seamlessly with other Victron components (solar controllers, inverters, monitoring). Around $1,100 to $1,400 for 100Ah.

Baintech (100Ah / 200Ah): An Australian brand offering solid lithium batteries at a more accessible price point. Good build quality, integrated BMS, and Bluetooth. Popular choice for Big Lappers who want lithium without the premium brand pricing. Around $800 to $1,100 for 100Ah.

iTechworld (100Ah / 200Ah): Another competitive Australian option. Lighter than some competitors, decent BMS, and aggressive pricing. Around $700 to $1,000 for 100Ah.

AGM vs Lithium: The Real-World Decision

This decision comes down to how you travel and what you can afford upfront.

Stick with AGM if: You’re on a tight budget, you mostly stay at powered caravan parks, or you free camp occasionally for one or two nights between park stays. A pair of quality 120Ah AGMs ($600 to $800 total) gives you 120Ah usable capacity, which handles a night or two of free camping comfortably. AGMs are also the right choice if you’re buying a second-hand van and aren’t sure yet how much free camping you’ll actually do.

Upgrade to lithium if: You plan to free camp regularly (more than a few nights per week), you need to run higher-draw appliances off-grid, weight is a concern (lithium saves 15 to 30kg over equivalent AGM), or you want the long-term cost savings of a battery that will outlast two or three sets of AGMs. A 200Ah lithium system with compatible charger and solar controller is $3,000 to $5,000 installed, but it gives you near-complete energy independence with adequate solar.

The middle ground: start with AGM, assess your actual needs over the first few months, and upgrade to lithium when (and if) you find the AGMs genuinely limiting. Many Big Lappers do exactly this, and it’s the lowest-risk approach.

Installation & Safety

Battery installation is one area where getting it wrong has real consequences. Incorrectly sized wiring can overheat and cause fires. Incompatible charging profiles can damage expensive lithium batteries. And poorly secured batteries in a moving caravan are a genuine safety hazard.

For AGM: A like-for-like replacement (swapping an old AGM for a new one of the same size) is straightforward DIY. Disconnect the negative terminal first, swap the battery, connect the positive terminal first. Ensure the battery is securely strapped down.

For lithium: Professional installation is strongly recommended unless you have genuine electrical experience. The installation typically involves replacing or reprogramming the DC-DC charger, solar controller, and 240V charger to lithium-compatible profiles. Wiring may need upgrading to handle lithium’s higher charge acceptance rates. A professional install runs $500 to $1,000 on top of the battery cost, but it’s done right.

Regardless of battery type, ensure your battery compartment has adequate ventilation, the battery is secured against movement in all directions (vibration, braking, and cornering), and all connections are tight with no exposed wiring.