The right size lithium camping battery comes down to two things: how much power you use in a day, and how long you go between charges. As a quick guide, a weekend 4WD setup running a fridge and lights is well-served by a 100Ah to 120Ah lithium battery, a touring caravan usually wants 200Ah to 300Ah, and an off-grid setup with an inverter, heating, and entertainment can need 300Ah or more. The rest of this guide shows you how to land on the exact number for your own rig, rather than guessing and buying twice.
The Short Answer By Setup Type
| Setup | Typical daily use | Suggested lithium capacity | Notes |
|---|---|---|---|
| Weekend 4WD or camper | Fridge, lights, phone charging | 100Ah to 120Ah | Add a small solar panel for extra days |
| Touring caravan | Fridge, lights, TV, charging | 200Ah to 300Ah | Pair with roof solar for free camping |
| Off-grid living | Above plus inverter and heating | 300Ah and up | Inverter loads push the number higher |
| Powered sites only | Short gaps between top-ups | 100Ah | Battery covers travel days, not full trips |
These are starting points, not rules. Two people with the same caravan can have very different needs depending on the climate they travel in, how long they free camp, and whether they have solar on the roof. Use the figures as a sanity check against the calculation below.
VoltX 48V 100Ah Pro Lithium LiFePO4 Battery
Why Amp-Hours Matter More Than the Sticker on the Battery
Capacity is measured in amp-hours (Ah), which tells you how much current a battery can deliver over time. A 100Ah battery can, in theory, supply 100 amps for one hour, or 5 amps for 20 hours.
The catch is usable capacity. With an older AGM or lead-acid battery, you should only draw down to about half before you risk shortening its life, so a 100Ah AGM really gives you around 50Ah of usable power. Lithium iron phosphate (LiFePO4) batteries are different. You can safely use 80 to 100 per cent of the rated capacity, so a 100Ah lithium, like the VoltX 12V 100Ah LiFePO4 Battery, delivers close to 90 to 100Ah of real, usable power. That is why a single 100Ah lithium often replaces a much larger AGM bank, at a fraction of the weight.
Gentrax 51V 100Ah Lithium LiFePO4 Battery
Here’s what one of our customers said:
“The voltx batteries are excellent and are working better than my more expensive Lifepo4 batteries - We use a lot of amps and keep a good charge and charge fast... Highly recommended.”
This matters for sizing because you should plan around usable capacity, not the headline number on the case. When you compare options, you are really comparing how much power you can take out before the battery management system steps in to protect the cells.
How to Work Out Your Daily Power Use
The honest way to size a battery is to add up what you draw in a typical day. List every appliance, estimate how many amps it pulls and how many hours it runs, then multiply:
Amps x hours = amp-hours per day
For appliances rated in watts, divide the watts by 12 to get the rough current at 12V. A 60W device draws about 5 amps. The table below gives typical figures to work from.
| Appliance | Typical draw | Hours per day | Amp hours per day |
|---|---|---|---|
| 12V fridge or freezer (40 to 60L) | Cycles on and off | Runs all day | 30 to 45 Ah |
| LED lights | 0.5 to 1A each | A few hours | 3 to 5 Ah |
| Water pump | Short bursts | Minutes | 1 to 2 Ah |
| Phone and device charging | 1 to 2A each | As needed | 2 to 5 Ah |
| Laptop or TV via inverter | Moderate | 1 to 3 hours | 8 to 15 Ah |
| Diesel or air heater | High on start-up | Overnight | 10 to 20 Ah |
| 12V fan | 0.3 to 0.5A | Several hours | 1 to 3 Ah |
The fridge is almost always the biggest single draw, and it works harder in hot weather, so build in headroom for an Australian summer. A fridge that sips 30Ah a day in mild conditions can climb past 45Ah on a 40-degree afternoon.
VoltX 12V 200Ah Slim Lithium LiFePO4 Battery
Days of Autonomy: How Long Between Charges?
Your daily figure is only half the picture. The other half is how many days you need to run before the battery is topped up again.
If you camp at powered sites every night, the battery only has to cover short gaps, and you can size conservatively. If you free camp or travel off-grid for several days, multiply your daily use by the number of days you want to stay out, then add a buffer so you are never scraping the bottom.
Most touring setups do not rely on the battery alone. Solar on the roof and a DC-DC charger that tops the battery up while you drive both reduce the size you need. A 200W solar panel in good Australian sun can return 40 to 80 amp-hours across a day, which can cover a modest fridge-based setup on its own. A DC-DC charger can put back 20 to 40 amps for every hour of driving. If you have steady solar or you drive most days, you can size the battery to cover roughly one to two days, rather than your entire trip.
Two Worked Examples
Weekend 4WD Camper
Say you run a 45L fridge, a couple of LED lights, charge two phones, and use a water pump. Your daily total might look like this:
- Fridge: about 40 Ah
- Lights: about 4 Ah
- Phone charging: about 4 Ah
- Water pump: about 2 Ah
- Daily total: about 50 Ah
For a two-night trip with no charging, that is around 100Ah of use. A 100Ah to 120Ah lithium battery covers it comfortably, because you can use most of the rated capacity, and a small solar panel buys you extra days off the grid.
Full-Time Touring Caravan
A larger rig with a 90L fridge, more lighting, a television, device charging, a diesel heater in the cooler months, and an inverter for small appliances adds up quickly:
- Fridge: about 60 Ah
- Lights: about 8 Ah
- TV and entertainment: about 10 Ah
- Device charging: about 6 Ah
- Diesel heater: about 15 Ah
- Inverter loads: about 15 Ah
- Daily total: about 115 Ah
To free camp for two days between charges, you are looking at well over 200Ah of usable power, so a 200Ah to 300Ah lithium bank, such as the VoltX 12V 200Ah Pro LiFePO4 Battery or the VoltX 12V 300Ah Pro LiFePO4 Battery, paired with solar, is the realistic range. Run a large inverter for a kettle or coffee machine, and you push toward the upper end.
Here’s what one of our customers said about the VoltX 12V 300Ah Pro LiFePO4 Battery:
“I have one of these batteries installed in our camping trailer to replace two small 40Ahr batteries. What a difference! We comfortably run our Dometic 70litre fridge, StarLink Mini, lighting, Nespresso machine and various other gadgets without fear of ever running out of power even when faced with a day or two of cloudy conditions. Charging is done with a solar system that produces up to 30A in full sun. Connected to a VoltX 2000W 240V inverter it doesn't struggle with voltage dropping to 12.4-12.8v with a 1500W load. On a full bench test discharge and recharge the battery discharged 312.1Ah and recharged 312.2Ah when delivered. Nine months after installation and frequent use the battery is still sitting at 312Ah capacity. It's a big battery so it won't fit normal battery boxes, but at only 27kg it is light!”
VoltX 12V 200Ah Pro Lithium LiFePO4 Battery
Common Sizing Mistakes
- Sizing to the rated number, not usable power. A lithium battery gives you most of its rated capacity, while the AGM you are replacing gives you about half. Compare like for like.
- Forgetting the inverter. Running a 240V appliance through an inverter pulls heavy current. A 2000W inverter under load can draw well over 150 amps from the battery, which drains capacity fast.
- Ignoring the climate. A fridge in a hot caravan works much harder than the same fridge in mild weather. Size for the worst conditions you actually travel in.
- Leaving no buffer. Sizing so the battery hits zero by morning leaves nothing for a cloudy day or a cold night. Plan to use a portion of the bank each day, not all of it.
- Buying small to save money, then buying again. A battery that is slightly too big is a minor cost. One that is too small means a second purchase and a reinstall.
Matching Capacity to the Right Battery
Once you have your number, the choice gets simpler. Look for a battery with the usable capacity to cover your daily draw and your days between charges, a quality battery management system to protect the cells, terminals that suit your cabling, and an ingress rating that suits where it will be mounted. For caravans and 4WDs, the practical sweet spots tend to be 100Ah to 120Ah for weekenders, and 200Ah and up for longer touring and off-grid living. For example, the VoltX 12V 100Ah Bluetooth Daly LiFePO4 Battery and the Gentrax 12V 200Ah LiFePO4 Battery in the Outbax range can be used for this.
You can compare options by capacity in our lithium camping battery range, where each battery lists its usable capacity, build and management features, so you can match the specification to the figure you have just worked out. Visit Outbax today and find the right power pack that best fits your outdoor adventure needs.
