A 2,000W inverter might sound like the right answer for a campervan, until you realise it can pull well over 170 amps from a 12V battery bank at full load. That is serious current, serious cabling and serious battery demand. Working out what size inverter for campervan use is not about buying the biggest unit in the catalogue. It is about matching the inverter to the appliances you will genuinely run, then building the DC side to handle the load safely.
For a properly sorted campervan, the inverter is one part of the system. Battery chemistry and capacity, solar input, DC-DC charging, cable size, fusing and battery monitoring all need to be chosen around the same real-world demand.
What size inverter for a campervan? Start with actual loads
An inverter changes your vehicle’s 12V or 24V battery power into 240V AC power. Its watt rating tells you how much AC power it can supply continuously. The number that matters is the appliance’s input wattage on its compliance label, not what you reckon it should use.
Start by writing down every 240V appliance you intend to use in the van. Include the ones that only run for a few minutes. A laptop charger may draw 65W to 140W, a TV around 50W to 150W, and a cordless-tool charger can vary wildly. Those are modest loads. The system changes quickly once you add appliances with heating elements or motors.
Kettles, toasters, hair dryers, coffee machines, air fryers and induction cooktops are the usual inverter killers. Many draw 1,000W to 2,400W or more. A microwave labelled as 900W cooking output can consume 1,300W to 1,600W from the inverter. Check the input figure, not the cooking figure.
Now consider what runs at the same time. A 1,500W inverter may run a 1,200W toaster on its own, but it has little room left if the battery charger, a laptop and another appliance are operating. Running at the inverter’s limit is also hard on the unit and the battery system, especially in a hot, enclosed cabinet.
As a practical guide, a 600W pure sine wave inverter suits light-duty charging and entertainment gear. A 1,000W to 1,200W unit gives a campervan more flexibility for power tools, compact kitchen gear and occasional higher loads. A 2,000W pure sine wave inverter is the common serious DIY choice when you want to run a microwave, coffee machine, toaster or induction appliance one at a time.
That does not mean 2,000W is automatically right. If your van is set up around 12V appliances, gas cooking and modest charging loads, a smaller inverter is more efficient, easier to wire and less likely to encourage battery-flattening habits.
Continuous power and surge power are different
Every decent inverter should show a continuous rating and a surge rating. Continuous power is what it can supply over time. Surge power is the brief extra capacity available when a motor starts.
Appliances with compressors, pumps and some power tools can demand a sharp startup surge before settling into a lower running load. A fridge compressor may run comfortably from an inverter, then trip a marginal unit when it starts. Do not choose an inverter purely on its peak rating. The continuous rating must cover the appliance, while the surge rating needs enough headroom for startup.
For sensitive electronics, chargers and many modern appliances, use a pure sine wave inverter. Modified sine wave units can be tempting on paper, but they may create noise, heat, poor performance or outright compatibility issues with chargers, audio equipment and motor-driven gear. A campervan electrical system is not the place to save a few dollars by fitting gear that is wrong for the job.
Match the inverter to the battery system
The AC watt figure only tells half the story. On the battery side, the inverter draws far more current because 12V is a low-voltage system. Use this working calculation:
DC current = AC watts ÷ battery voltage ÷ inverter efficiency
Allow around 90 per cent efficiency for a quality inverter under a substantial load. A 2,000W load on a 12.8V lithium battery bank can draw roughly 174A. On a 24V system, that same load is closer to 87A. This is why 24V makes sense in larger campers and motorhomes with sustained high-power AC loads.
A 100Ah lithium battery does not magically become a 2,000W power station because the inverter is rated at 2,000W. The battery must be capable of delivering the required current, its battery management system must allow it, and the cable, fuse and isolator must all be rated for that current. One weak point can create voltage drop, nuisance shutdowns or dangerous heat.
Runtime matters as well. A 12V 100Ah lithium battery holds roughly 1,280Wh of energy in ideal terms. After inverter losses, a 1,000W appliance could flatten it in a little over an hour if run continuously. In practice, high loads, heat and battery protection settings may reduce that further. Lead-acid batteries require even more caution because repeatedly discharging them deeply will shorten their service life.
Solar helps replace energy, but it does not make a high-draw appliance free to run. A 2,000W coffee machine can take more energy in ten minutes than a small solar panel produces over several hours. If you are building for off-grid touring, size the battery and charging system around daily watt-hours, not just the inverter’s headline rating.
Cables, fuses and installation are not optional extras
At inverter currents, undersized cable is a failure point waiting to happen. The inverter should be mounted close to the battery bank using correctly sized copper cable, with a suitable fuse or circuit breaker positioned close to the battery positive terminal. Long, skinny cables cause voltage drop. The inverter sees low voltage, shuts down under load, and people often blame the inverter when the wiring is the real problem.
The battery negative return must be equally capable. Connections need clean contact surfaces, proper crimp lugs, insulation and strain relief. Do not feed a large inverter through a small accessory socket, light cable or a random distribution block. A 2,000W inverter on 12V needs installation standards that match the current it can demand.
Ventilation matters too. Inverters make heat, particularly when loaded hard. Mount the unit where it stays dry, has airflow and can be accessed for checking terminals and reset controls. Keep it away from battery fumes and do not bury it behind bedding or gear in a packed storage compartment.
If you are adding a 240V outlet circuit, the AC side needs to be set up to the applicable Australian requirements. The DC installation is well within the reach of an experienced DIY builder who understands high-current systems, but fixed 240V wiring is not a guess-and-go job.
A sensible way to choose your inverter size
Choose the largest appliance you will actually run, then add the simultaneous loads that cannot be switched off. Add sensible headroom rather than selecting a unit that will run flat-out every time you boil water. If your largest planned load is a 1,300W microwave and you will not run it beside other heavy appliances, a quality 1,600W to 2,000W inverter gives room to work. If you only need laptops, camera batteries and a TV, 600W to 1,000W is generally the cleaner answer.
Avoid building around appliances you might use once a year. High-power AC cooking in a 12V campervan requires a large battery bank and heavy cabling. Sometimes a 12V compressor fridge, USB-C charging, gas cooking and a smaller inverter make for a far more practical touring setup.
Electric air conditioning deserves separate planning. It is a sustained, high-demand load rather than a quick burst like a toaster. If you are considering 12V or 24V electric A/C, build the battery, charging and cable system around its measured running current and expected operating time. At Tuck's Performance, that real-load approach is central to testing gear for Australian heat, rather than relying on optimistic catalogue numbers.
The best inverter is the one that handles your real appliances without stressing the battery bank or wiring. Build the numbers first, allow for hot days and charging losses, and you will have a campervan power system that works when you are camped well away from a powered site.
