Choosing the Right Deep-Cycle Battery for Your 4×4, Boat or Caravan
Author: Toby Date Posted:7 November 2025
Heading out on a trip with the wrong battery setup is a fast way to ruin the fun. Maybe you need to keep a fridge humming in the back of the ute, run lights in the caravan at night, or power electronics while you’re out on the water. That’s where the right deep-cycle battery makes all the difference. Unlike a starter battery, which just cranks your engine, a deep-cycle battery is built to deliver steady power for hours at a time. But not all are created equal – so let’s break down how to choose the right one for your setup.
AGM vs Lithium vs Gel vs Flooded vs VRLA – What’s the Difference?
- AGM (Absorbent Glass Mat): Sealed, spill-proof, and vibration-resistant. Great for 4WDs and caravans on corrugated roads. Century’s AGM range is a popular pick here, with capacities from compact 32Ah right through to 165Ah.Flooded Lead-Acid: The traditional deep-cycle battery. Reliable and affordable, but needs regular maintenance (like topping up electrolyte water). Best for budget caravan setups or stationary use.
- Gel: Handles deep discharges well, with slower recharge times. Good for steady appliance loads like fridges and lighting in caravans or solar systems.
- Lithium (LiFePO4): Lightweight, long-lasting, and high-performing. Renogy’s lithium range is ideal for serious touring rigs, boats, or caravans running large inverters. Higher upfront cost, but far more cycles and better efficiency.
- VRLA (Valve-Regulated Lead Acid): An umbrella category that includes AGM and Gel types. These sealed batteries regulate internal gas pressure via a safety valve, making them maintenance-free and safer for enclosed spaces like caravans and boats.
How to Size Your Deep-Cycle Battery
Choosing the right amp-hour (Ah) capacity depends on what you’re running, and for how long. A common mistake is undersizing, which leaves you short of power on longer trips. Here’s a quick guide:
| Application | Typical Use | Recommended Capacity (Ah) | Notes |
|---|---|---|---|
| Camping (basic setup) | LED lights, phone charging | 50–75Ah | Compact AGM is ideal for weekend trips |
| Camping (with fridge) | 40L–60L fridge, lights, small devices | 100–120Ah | AGM or Lithium recommended for longer run time |
| 4×4 Touring / Off-Road | Fridge, lights, compressor, winch (short use) | 120–150Ah | Lithium offers weight savings for touring rigs |
| Caravan (short trips) | Fridge, lighting, water pump | 120–150Ah | AGM is common, Lithium for extended trips |
| Caravan (off-grid/long trips) | Fridge, lighting, TV, inverter appliances | 200Ah+ | Lithium or Industrial deep-cycle best for solar setups |
| Marine (small boats) | Sounder, lights, small electronics | 75–100Ah | AGM suits vibration and salt conditions |
| Marine (large boats) | Trolling motor, multiple electronics | 150–200Ah+ | Lithium recommended for efficiency and weight savings |
As a rule of thumb: add up the total watts of your gear, divide by 12 (volts), and that’s the amps you’ll need per hour. Multiply by the number of hours you want to run it, and you’ll get the Ah capacity required. Always add a buffer of at least 20–30%.
Choosing for a 4×4
If you’re running a dual-battery setup, your deep-cycle unit powers fridges, camp lights, compressors, and other accessories while parked. For weekend trips, a 75–120Ah AGM is often enough. For extended touring or energy-hungry gear like a winch or inverter, lithium in the 120–200Ah range will give you more usable capacity and faster recharging.
Choosing for a Caravan
Caravans often run multiple systems at once – fridges, pumps, lights, and sometimes TVs. For smaller vans, 120–150Ah AGM works well. For serious off-grid caravanning, look at 200Ah+ lithium or industrial-grade batteries paired with solar for long-term freedom.
Choosing for a Boat
Boats deal with vibration, salt, and long discharge cycles. For smaller boats, 75–100Ah AGM or Gel is solid. For larger boats running trolling motors or electronics, 150–200Ah+ lithium is the way to go, offering lighter weight and more usable power.
Choosing the Best Battery for Your Setup
The right deep-cycle battery depends on how you use your 4×4, caravan, or boat. For light weekend trips, an AGM battery is hard to beat. For long touring and serious off-grid power, lithium will give you the most freedom. Caravanners and boat owners can also look to Gel, Flooded, or VRLA batteries for steady, reliable power supply.
At Superspares, we stock a wide range of deep-cycle batteries – from Century’s trusted AGM, Flooded, and Gel models through to Renogy’s advanced lithium range. When you’re ready to upgrade, you’ll find everything you need at our auto parts online store – keeping your gear powered wherever the road or water takes you.
Written by Toby Martin
Automotive Content Specialist
