Your house battery is the foundation of your caravan’s electrical system. Everything that works off-grid, from lights to the fridge to your phone charger, runs through it. Understanding what type of battery you have, how it behaves, and how to care for it is the most practical electrical knowledge you can have as a caravanner.
Your house battery lives in a battery box, usually in the front boot or under the chassis. Know where it is and what type it is.
Battery Types
AGM (Absorbed Glass Mat): The standard factory-fitted battery in most caravans. Sealed, maintenance-free, and affordable ($200 to $400 for a 100Ah battery). The Century N70T and Bosch AGM are common factory-fit options, while the Giant Power 120Ah AGM is a popular aftermarket upgrade. AGM batteries are reliable but have limitations: they should only be discharged to 50% (so a 100Ah battery gives you 50Ah of usable power), they charge slowly (particularly the last 20%), and they typically last 300 to 500 cycles before performance degrades noticeably. Lifespan: 2 to 4 years with proper care.
Lithium Iron Phosphate (LiFePO4): The premium option and increasingly the standard in mid-range and high-end caravans. More expensive ($800 to $1,800 for a 100Ah battery) but dramatically better performance: 80 to 90% usable capacity (so 100Ah gives you 80 to 90Ah), charges 3 to 5 times faster than AGM, weighs roughly half as much, and lasts 2,000+ cycles. The Enerdrive ePOWER B-TEC is the benchmark for Australian caravan lithium batteries, with the Renogy 100Ah and Kings 100Ah Slimline offering solid options at lower price points. Lifespan: 7 to 10+ years. For serious off-grid travel, lithium pays for itself through performance and longevity.
Gel: Occasionally found in older caravans. Similar limitations to AGM but even more sensitive to charging rates. Being phased out in favour of AGM and lithium.
| Feature | AGM | Lithium (LiFePO4) |
|---|---|---|
| Cost (100Ah) | $200–$400 | $800–$1,800 |
| Usable capacity | 50% | 80–90% |
| Weight (100Ah) | ~30kg | ~12–15kg |
| Cycle life | 300–500 | 2,000+ |
| Charge speed | Slow (8–12 hrs full) | Fast (2–4 hrs full) |
| Lifespan | 2–4 years | 7–10+ years |
How Your Battery Charges
Mains charger (240V): When plugged into a powered site, your onboard charger converts 240V to the correct charging voltage for your battery type. Most chargers are multi-stage, meaning they adjust the voltage as the battery fills. The Enerdrive ePOWER and Projecta Intelli-Charge are two of the most common aftermarket options. Ensure your charger has a setting for your battery type (AGM, lithium, or gel); charging lithium batteries with an AGM-only charger can damage them or fail to charge fully.
DC-DC charger: Installed between your tow vehicle and the caravan, this takes power from the car’s alternator while driving and delivers it at the correct voltage and current for your house batteries. Essential for modern vehicles with smart alternators that limit charging output. The Redarc BCDC1250D (50A) is the gold standard; the Renogy 40A DC-DC and Enerdrive DC40 are also excellent. A 30A to 40A DC-DC charger can put 20 to 30Ah into your batteries per hour of driving.
Solar controller: Your solar panels feed power through a solar controller (either PWM or MPPT) that regulates the charge going into your batteries. MPPT controllers are more efficient (10 to 30% more output) and worth the small extra cost. The Victron SmartSolar range and Redarc MPPT regulators are the most popular choices in Australian caravan setups.
Battery Care
Don’t over-discharge AGM batteries. Regularly discharging AGM below 50% dramatically shortens their life. A battery monitor like the Victron SmartShunt ($150 to $200) or the Simarine Pico ($300 to $400) lets you track state of charge precisely so you know exactly when to stop drawing power or fire up the generator.
Keep batteries charged. Leaving batteries in a discharged state (particularly AGM) causes sulphation, which permanently reduces capacity. If storing the van, connect to a trickle charger (the CTEK MXS 5.0 is a reliable choice at $100 to $130) or ensure solar is maintaining the charge.
Check connections. Battery terminals should be clean, tight, and free of corrosion. A loose or corroded connection reduces charging efficiency and can cause voltage drops.
Monitor temperature. Extreme heat reduces battery life. If your battery box is in direct sun, consider ventilation or relocation. Lithium batteries have built-in BMS (Battery Management System) that protects against temperature extremes; AGM does not.
- AGM batteries are affordable but only offer 50% usable capacity. Lithium offers 80 to 90% and lasts 3 to 5 times longer.
- Batteries charge from three sources: mains charger, DC-DC charger (while driving), and solar. Most setups use all three.
- Never regularly discharge AGM below 50%. Use a battery monitor to track state of charge.
- Ensure your chargers (mains and DC-DC) are set to the correct battery type. Mismatched charging damages batteries.
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