Most tourers buy a camping battery on a hunch and only learn if they got it right on the worst possible night. Here is the arithmetic that takes the guesswork out, built around how you really camp.
Buying a camping battery is a lot like buying insurance. People tend to get too much or too little, and they only find out which one on the night it matters. Size the bank too small, and you are rationing the fridge by day two of a long weekend. Size it too big, and you are hauling dead weight, and dead money, around the country.
The good news is that sizing a lithium battery bank is not guesswork. It is arithmetic, and it starts with how you actually camp rather than with a number someone quoted on a forum. This guide walks through a five-step method used by seasoned tourers and the team at Outbax: work out your style, audit your daily power, apply the lithium advantage, add a safety cushion, then match the bank to your recharge habits. By the end, you will have a real amp-hour target and a shortlist of batteries that fit it.
» MORE: Compare capacities across the Outbax lithium battery range
Step 1: Start with Your Camping Style, Not a Capacity Number
Your camping style decides two things that matter more than any spec sheet: how much power you burn in a day, and how many days you need to run without sun or a drive to top up. Battery makers call that second figure autonomy. Get your style right first, and the capacity number almost chooses itself.
The Weekend Warrior (One To Two Nights)
You leave home with a full battery, camp Friday to Sunday, then drive back. Power use is modest: a fridge, a few lights, and some phone charging. You rarely need a complex solar setup because you are never off the charger for long. A single 100Ah lithium battery is usually plenty, and many weekenders never come close to flattening it.
The Off-Grid Overlander (Three To Seven Nights)
You camp well away from powered sites, often free camping, and you move every few days. Solar and alternator charging carry the load. Consumption climbs because you are living out of the setup: a fridge running around the clock, a diesel heater on cold nights, lights, and device charging. Most overlanders land somewhere between 200Ah and 300Ah once a cushion is added.
The Digital Nomad and Full-Timer
You work on the road. Laptops, a Starlink dish, a coffee machine, and maybe an induction cooktop push daily use high, and you cannot afford a flat battery in the middle of a meeting. This group needs a large bank paired with serious recharging from multiple sources. Think 300Ah and up, backed by solar and a high-output DC-DC charger.
Be honest about which camper you are, not the one you picture on the perfect trip. Sizing for a fantasy setup is how people end up paying for capacity they use twice a year.
Queens 12V 95AH Lithium Iron Phosphate Battery
Step 2: Run a Quick Energy Audit to Find Your Daily Amp-Hours
This is the step most people skip, and it is the one that makes the whole calculation trustworthy. Lithium batteries are rated in amp-hours (Ah). To find your daily need, you add up the amp-hours every appliance pulls across a typical day on the road.
The Formula That Does the Heavy Lifting
The maths is simple. Take an appliance’s current draw in amps, multiply it by the hours it runs each day, and you have its amp-hours. Do that for every device, add the results, and that single number becomes the foundation of everything that follows.
Two formulas worth memorising:
Daily use: Amps × Hours = Amp-hours (Ah) per day
Solar to fit: 2W of solar for every 1Ah of battery capacity
A Worked Camping Example
Here is a realistic day for a couple touring in a caravan. The figures are indicative, and your own draw will vary with appliance and climate, but the shape is typical.
| Appliance | Average draw at 12V | Hours per day | Daily use |
|---|---|---|---|
| 12V fridge or freezer | 2.5A (cycles on and off) | 24 | 40 to 60Ah |
| LED lights (four) | 1.0A | 4 | 4Ah |
| Water pump | 5.0A | 0.25 (15 min) | 1.25Ah |
| Phone and tablet charging | 2.0A | 3 | 6Ah |
| Laptop via inverter | 5.0A | 2 | 10Ah |
| Diesel heater (fan and ignition) | 2.0A | 8 | 16Ah |
Total that scenario, and you're looking at about 80Ah a day. Notice the fridge alone is often half the budget, which is exactly why it pays to check its real draw rather than guess. Your 12V fridge is the single biggest lever in the whole audit.
Converting 230V Appliances Through an Inverter
A microwave, coffee machine, or induction hob runs on 230V through an inverter, and its label shows watts, not amps. A quick rule of thumb bridges the gap: divide the appliance watts by 10 to get the rough 12V amp draw. A 1,200W coffee machine pulls roughly 120A while it runs, so even a two-minute brew is a meaningful slice of watt-hours. This is where nomads and full-timers watch their daily figure balloon, and why the inverter itself deserves a line in the audit.
» MORE: How to choose the right lithium battery for your needs
VoltX 12V 100Ah Blade Lithium LiFePO4 Battery
Step 3: Apply the Lithium Advantage and Add an Autonomy Cushion
Once you know your daily draw, two adjustments turn it into a real bank size. The first is the very reason you are buying lithium in the first place.
Why Lithium Gives You Usable Capacity That Lead-Acid Cannot
Depth of discharge is the share of a battery’s rated capacity you can safely use. Traditional AGM and lead-acid batteries should only be drawn down to about 50 per cent before you shorten their life. A quality lithium iron phosphate or LiFePO4 battery can safely deliver 80 to 100 per cent of its rated capacity, watched over by its built-in battery management system (BMS).
The practical effect is dramatic. If your audit says you need 100Ah of usable power, an AGM setup would need a 200Ah bank to deliver it. With lithium, you need roughly 100Ah to 120Ah. That is why a lithium deep cycle battery can be smaller, lighter and still outlast the lead-acid brick it replaces.
Choosing Your Autonomy Multiplier
Autonomy is the number of days you want to camp in shade, rain, or without moving the vehicle before the battery runs down. Pick a multiplier that matches your risk tolerance:
- Fair weather camper: 1.2. You assume solar will catch up most days.
- Remote or all-weather camper: 2.0 to 3.0. You want two to three days of backup during storms or under heavy tree cover.
From Audit to Bank Size
Say your audit lands at 80Ah a day and you want two days of true autonomy. Multiply: 80Ah × 2 = 160Ah of usable power. Because lithium hands you most of the rated figure, you are looking at a bank in the region of 150Ah to 200Ah. For many tourers, that points straight to a 200Ah lithium battery, with headroom for the odd bad-weather run.
VoltX 24V 100Ah Pro Lithium LiFePO4 Battery
Step 4: Balance the Bank with How You Actually Recharge
A big battery is useless if your camping habits never let you recharge it. This step separates a setup that works from one that limps home early. Match your recharging to your bank, not the other way around.
If You Drive Most Days
Movement is free charging. A high-output DC-DC charger wired to your vehicle’s alternator can push serious current into the bank while you drive. A 40A to 50A unit can replenish up to around 100Ah in a two-hour drive, which suits overlanders who rarely sit still for long. The VoltX SRNE 12V 50A DC to DC MPPT LiFePO4 Battery Charger is built for exactly this job, and it accepts solar input through the same unit so you can run both sources at once.
If You Stay Parked for Days
When the vehicle is not moving, solar does the work. A reliable rule of thumb is 2W of solar for every 1Ah of lithium capacity, so a 200Ah bank wants roughly 400W of panels. Undersize the array, and your recovery time stretches out, especially in winter when Australian daylight hours and sun angle both drop. Free camping in one spot for a week is the scenario that punishes a weak solar setup.
Recovery Time and Topping Up a Bigger Bank
Recovery time is how long it takes to return the bank to full, and it depends on how deep you drew it down, your charge source and the weather. The honest planning rule is simple: the larger your bank, the more charging input you need to refill it in a sensible window. A 300Ah bank with only 200W of solar will rarely see 100 per cent in overcast conditions. Pair capacity with charging capacity, and keep a portable generator in mind as a backup for long grey stretches.
» MORE: Browse DC to DC and solar chargers at Outbax
Step 5: Match Your Number to the Right Outbax Lithium Battery
You now have a target figure. Here is how the common camping styles map to real batteries in the Outbax lithium range, so you can turn arithmetic into a purchase.
100Ah for Weekends and Light Off-Grid Use
If your audit sits under about 70Ah a day and you charge often, a single 100Ah battery is the sweet spot for weight, cost and simplicity. The VoltX 12V 100Ah LiFePO4 Battery is the popular weekend choice, and the VoltX 12V 100Ah Blade LiFePO4 Battery offers the same capacity in a flatter footprint for tight vehicle installs.
Here’s what one of our customers said about the VoltX 12V 100Ah Battery:
“Been using my VoltX 12V 100Ah LiFePO4 Basic Lithium Battery for over 6 months now and it's been working like a dream. It's been super reliable and holds its charge really well. Great product.”
200Ah to 300Ah for Extended Touring and Caravans
Most off-grid tourers and caravan owners land here once they add a cushion. The Outbax 12V 200Ah Pro LiFePO4 Battery covers most two-person setups, while the VoltX 12V 300Ah Pro LiFePO4 Battery suits full-timers running heavier loads. Both can be wired in parallel if you prefer to build the bank in stages.
Here’s what one of our customers said about the VoltX 12V 200Ah Battery:
“Very happy customer so far. was quick to deliver good communication and tracking. The battery fits in the same space as the old 100amp battery with only minor adjustments. only time will tell as to how long it will last however with a 5-year warranty, I'm pretty confident it will last the distance. Definitely recommend Outbax.”
Slimline Options for Tight Installs
Space under a seat or inside a ute canopy is often the real constraint, not capacity. The VoltX 12V 200Ah Slim LiFePO4 Battery packs a full 200Ah into a narrow case designed to slot where a standard box will not fit. For caravans and 4WDs where every centimetre counts, a slimline lithium battery lets you carry the capacity your numbers call for without redesigning the whole compartment.
Whatever tier your calculation points to, buy the capacity your habits justify, not the biggest unit on the shelf. Outbax lists warranty, cycle life, and dimensions on every product, so you can match the spec to your install before you commit.
VoltX 48V 100Ah Pro Lithium LiFePO4 Battery
The Bottom Line
Sizing a lithium battery bank comes down to five honest steps: know your camping style, audit your daily amp hours, use the lithium advantage on depth of discharge, add an autonomy cushion, then balance the bank against how you recharge. Do the arithmetic once, and you sidestep both the flat battery on night two and the dead weight you paid for and never use. The right bank is simply the one matched to how you actually camp. When you are ready to compare capacities, chargers and form factors side by side, the Outbax lithium deep cycle battery range gives you the specs to make the call with confidence.
