What Size Inverter Do You Need for a Camper Trailer? (2026 Australian Guide)
Inverter sizing for Australian camper trailers: appliance wattage table, pure vs modified sine wave, 1000W vs 2000W vs 3000W scenarios, cable sizing, and per-model Breath Trailer recommendations.
Most camper trailer buyers focus intensely on solar panels and battery capacity, then get to their first remote camp and discover the thing they forgot: an inverter. Without one, your 240V kettle, laptop charger, coffee machine, and CPAP machine are dead weight. With the wrong one, your laptop power supply hums, your fridge trips faults, and your $800 inverter runs at 60°C trying to start a load it was never rated for.
An inverter converts your 12V battery bank into 240V AC — the same current that comes out of a wall socket at home. In 2026, a quality pure sine wave inverter sized correctly for your setup costs anywhere from $300 to $1,500 in Australia. Get the sizing right and you will forget it is even there. Get it wrong and you will replace it on the road.
This guide gives you the exact maths: an appliance wattage table, a three-step sizing formula, scenario breakdowns for 1000W, 2000W, and 3000W units, and specific recommendations for each Breath Trailer model.
What Does an Inverter Actually Do?
Your camper trailer’s 12V battery system powers 12V appliances directly — LED lighting, the fridge compressor, the water pump, USB charging — all without an inverter. But many appliances you own at home are 240V AC only: laptops with brick chargers, coffee machines, microwaves, electric kettles, CPAP machines with heated humidifiers, and power tools.
An inverter bridges that gap. It draws DC current from the battery bank and converts it to AC current at 240V/50Hz — matching Australian grid standards — so those appliances run as they would at home.
The critical thing to understand: an inverter does not create power. It only converts it. Every watt you consume through the inverter comes from your battery bank, with a conversion efficiency loss of roughly 10–15%. A 2000W inverter drawing maximum load will pull around 200A from a 12V battery — a very large current that requires appropriately rated wiring and fusing.
Pure Sine Wave vs Modified Sine Wave: The Decision You Cannot Skip
Before sizing, you must choose the inverter type. This is not a preference — it determines what you can and cannot run safely.
| Feature | Pure Sine Wave (PSW) | Modified Sine Wave (MSW) |
|---|---|---|
| Output waveform | Clean sine — identical to grid | Stepped approximation |
| Compatible appliances | All 240V appliances | Simple resistive loads only |
| Sensitive electronics | Safe (laptops, CPAP, TVs) | Can damage or cause overheating |
| Audio/video | No buzz or hum | Often produces audible hum |
| Induction motors | Full efficiency | Runs 20–30% hotter, may fail |
| 2026 AU price (1000W) | $300–750 (REDARC, KickAss, Victron) | $80–200 |
| Recommended for camping | Yes — always | No, avoid for most uses |
The verdict: for any serious off-grid setup, buy a pure sine wave inverter. Modified sine wave units cost $150 less but create problems that cost far more — a fried laptop power supply, a CPAP unit that fails mid-trip, or a microwave that runs at half capacity and overheats.
The one exception: if you need a small inverter purely to run an incandescent lamp or a basic power tool for occasional use, a modified sine wave unit will work. But for $100 more you can buy pure sine wave and eliminate the risk entirely.
How to Size an Inverter: The Three-Step Method
Step 1 — List every 240V appliance you want to run simultaneously
Write down each 240V appliance and its running wattage. Running watts is the continuous power draw once the appliance is operating normally (not including startup surge, which we address in Step 2).
Step 2 — Identify the highest-surge appliance
Any appliance with a motor, compressor, or heating element draws a surge of 2–6× its running watts for the first 1–3 seconds at startup. A 1200W coffee machine may surge to 3000W for a fraction of a second. Your inverter must handle that surge without tripping.
Most inverters are rated with two figures: a continuous rating (e.g. 2000W) and a peak/surge rating (e.g. 4000W for 3 seconds). Your peak load must stay within the surge rating.
Step 3 — Add 20% safety headroom
Inverters run more efficiently and last longer when they operate at 70–80% of their rated capacity. A 2000W continuous load warrants a 2500W inverter; a 1200W continuous load warrants a 1500W inverter.
Formula: Inverter size = (sum of simultaneous running watts) × 1.25, then round up to the next standard size (1000W / 1500W / 2000W / 2500W / 3000W).
Appliance Wattage Table: What Actually Draws Power
| Appliance | Running Watts | Surge Watts | Notes |
|---|---|---|---|
| Laptop (15”) | 65–90W | 90–120W | Low draw — easily handled by any inverter |
| Phone / tablet charging | 10–30W per device | Minimal | Negligible |
| LED lighting (240V) | 5–15W per globe | Minimal | Better run via 12V LEDs directly |
| CPAP machine (no humidifier) | 30–60W | 60–80W | PSW required; humidifier adds 100–200W |
| CPAP machine (with humidifier) | 150–250W | 200–300W | PSW non-negotiable |
| Coffee machine (espresso) | 1,000–1,800W | 2,000–3,500W | Highest domestic surge |
| Electric kettle (standard) | 2,000–2,400W | 2,200–2,600W | High draw — limit to short bursts |
| Microwave (compact 700W) | 700–900W | 1,000–1,400W | Common camping use |
| Hair dryer (travel size) | 800–1,200W | 1,000–1,500W | Consider 12V alternative |
| Electric blanket | 60–150W | 80–150W | Low draw — works well overnight |
| Power drill | 400–800W | 1,200–2,400W | High surge: size inverter accordingly |
| 240V fridge (compressor) | 150–400W | 400–1,200W | Run your fridge via 12V instead |
| Air conditioner (small 2kW) | 600–800W | 2,000–4,000W | Requires 3000W+ inverter minimum |
| TV (32” LED) | 30–80W | 80–100W | Low draw; PSW required |
Practical note on fridges: virtually every quality camping fridge sold in Australia (Engel, ARB, Brass Monkey) runs natively on 12V. Never run your 12V compressor fridge through a 240V inverter — you lose efficiency twice (12V→240V→12V conversion). Wire it direct.
What Each Inverter Size Handles in Practice
1000W Pure Sine Wave — The Essentials Setup
Best for: Breath Essential and Breath Plus owners who camp in powered sites most of the time, or who only need 240V for laptops, CPAP, tablets, and occasional phone charging.
A 1000W unit handles: 2 laptops simultaneously, a CPAP with heated humidifier, a 32” TV, and all your USB charging — simultaneously — with headroom to spare. What it cannot do: run a kettle, coffee machine, or microwave at the same time as other high-draw appliances.
Price range (AU, 2026): REDARC R-12-1000RS ~$557–742; KickAss 1000W PSW ~$299–349; Victron Phoenix ~$420–520.
2000W Pure Sine Wave — The Sweet Spot
Best for: most off-grid campers doing extended trips — couples using a coffee machine each morning, families with a microwave for quick meals, grey nomads running a CPAP and a kettle in sequence.
A 2000W unit covers: a compact microwave (700W), two laptops, CPAP with humidifier, phone charging — all simultaneously. You can also run a coffee machine if you sequence it (not alongside the microwave). The kettle is borderline — a 2000W continuous rating with a 4000W surge rating will handle a standard 2400W kettle, but check your specific model’s surge spec.
Price range (AU, 2026): REDARC 2000W PSW ~$1,400–1,515; KickAss 2000W PSW ~$499–599; Victron 2000VA ~$850–1,000.
3000W Pure Sine Wave — The High-Comfort Setup
Best for: families with teenagers, grey nomads who use a travel induction cooktop, and campers who want to run a small air conditioner on shore power supplements or from a large lithium bank.
A 3000W unit handles everything the 2000W can, plus: a 1200W espresso machine alongside other loads, a full travel kettle, and a small 2kW reverse-cycle air conditioner (check surge spec — some 2kW units surge past 4000W at startup). This is also the minimum size for anyone considering running air conditioning off inverter power.
Price range (AU, 2026): KickAss 3000W PSW ~$699–799; Victron 3000VA ~$1,200–1,500; Enerdrive 3000W ~$950–1,100.
Inverter Size by Breath Trailer Model
Each Breath Trailer ships from the Sydney workshop with a KICKASS lithium battery bank and REDARC DC-DC charging as standard (varies by model). Here is how inverter sizing maps to each model’s real-world use case.
| Model | Battery (standard) | Recommended Inverter | Why |
|---|---|---|---|
| Essential $19,990 | 100Ah LiFePO4 | 1000W PSW | Essential is the minimalist setup — laptops, CPAP, USB charging. A 1000W unit draws ~83A at full load, which the 100Ah bank can sustain for ~1.2 hours. |
| Plus $25,740 | 100Ah LiFePO4 | 1000–2000W PSW | The Plus adds a 12V fridge as standard. A 2000W inverter unlocks the microwave-and-laptop scenario for couples doing base camps. |
| Ultra $30,290 | 100Ah LiFePO4 (upgradeable) | 2000W PSW | The Ultra’s external shower, external kitchen bench, and larger footprint suit extended off-grid stays. 2000W handles the morning-coffee-and-laptop routine without compromise. |
| Max $39,000 | 200Ah LiFePO4 (standard) | 2000–3000W PSW | The Max’s interior bathroom, standing headroom, queen bed, and self-contained spec attract grey nomads and long-tourers who want kettle + CPAP + microwave + TV simultaneously. The 200Ah bank sustains a 2000W draw for ~1.4 hours before needing solar top-up. |
The Breath Max is the only teardrop on the Australian market under $50,000 with a full interior bathroom and self-contained certification — the model most likely to be used truly off-grid for multiple nights. It benefits most from the larger 2000–3000W inverter.
Battery Bank: The Inverter Equation Nobody Talks About
An inverter is only as useful as the battery bank behind it. Run the maths before you buy.
Formula: Runtime (hours) = (Battery Ah × Voltage × Usable %) ÷ Inverter load (W)
- For a 100Ah LiFePO4 at 12V (80% usable = 80Ah usable):
80Ah × 12V = 960Wh usable - Running a 700W microwave:
960Wh ÷ 700W = 1.37 hoursof continuous microwave runtime - Running a 60W CPAP overnight (8 hours):
60W × 8h = 480Wh consumed— well within the 960Wh budget - Running a 2000W coffee machine for 3 minutes morning and evening:
2000W × 0.05h × 2 = 200Wh— manageable if solar replenishes during the day
Key insight: high-wattage appliances like kettles and microwaves are not a problem if you use them briefly and your solar array tops the bank back up during daylight. The danger is running a 2000W inverter load for extended periods from a single 100Ah battery. Invest in more solar and battery capacity before investing in a bigger inverter.
For a deep-dive on pairing battery and solar correctly, see Understanding Camper Trailer Solar Systems and AGM vs Lithium Batteries for Camper Trailers.
Installation Basics: Cable, Fuse, and Location
A poorly installed inverter is a fire risk. These are the non-negotiables.
Cable sizing
An inverter draws large DC currents. A 2000W inverter at 12V draws approximately 185A continuous. Use this table as a minimum guide (pure copper cable, not copper-clad aluminium):
| Inverter Size | Cable Run < 1.5m | Cable Run 1.5–3m | Cable Run 3–5m |
|---|---|---|---|
| 1000W (12V) | 50mm² | 70mm² | 95mm² |
| 2000W (12V) | 70mm² | 95mm² | 120mm² |
| 3000W (12V) | 95mm² | 120mm² | 150mm² |
Undersized cable gets hot, loses voltage (reducing inverter efficiency), and is a fire hazard. If in doubt, go bigger.
Fuse position and rating
Always install an ANL fuse (or equivalent) within 150mm of the positive battery terminal. This is AS/NZS 3000 standard in Australia and protects your wiring in the event of a short circuit. The fuse must be rated to match the cable — not the inverter.
| Cable size | Maximum fuse |
|---|---|
| 50mm² | 200A ANL |
| 70mm² | 300A ANL |
| 95mm² | 400A ANL |
Location
Install the inverter as close to the battery as possible (minimises cable run and voltage drop), in a ventilated location (inverters generate significant heat at load), and away from water entry points. Do not install in an enclosed box without airflow — a thermally protected inverter will shut down before it fails, but overheating shortens lifespan.
For a complete wiring overview, the camper trailer towing guide includes pre-trip electrical checks, and the ultimate off-grid setup guide covers system integration.
Inverter vs Inverter-Generator: When a Genny Makes More Sense
An inverter converts stored battery power. An inverter-generator (petrol) produces its own power on demand. They solve different problems.
| Factor | 12V Battery Inverter | Petrol Inverter-Generator |
|---|---|---|
| Noise at camp | Silent | 50–65 dB (typical Honda EU22i) |
| Fuel cost | None (solar + battery) | ~$2–4/hr at light load (petrol) |
| Setup time | Instant (always on) | Pull-start, warm-up |
| Campsite rules | Permitted anywhere | Many parks prohibit generators 8pm–8am |
| Surge capacity | Up to 4000W (2000W inverter) | 1800–3500W continuous (typical models) |
| Weight | 3–7 kg | 17–28 kg |
| Best use | Extended off-grid stays with solar | High-draw appliances (A/C, welder) or no solar |
| 2026 AU price | $300–1,500 | Honda EU22i ~$2,200; Yamaha EF2800 ~$1,900 |
For most teardrop campers with a proper solar and lithium setup, a petrol generator is unnecessary — and often unwelcome in the national parks and free-camping spots where teardrop owners tend to gravitate. The off-grid teardrop camper guide covers exactly this trade-off.
The one case where a generator wins: if you want to run air conditioning off-grid without a managed solar + battery solution, you need a petrol source. A 2kW reverse-cycle air conditioner running for 8 hours overnight consumes 6–8kWh — a load that requires either a massive battery bank (600Ah+) or a generator.
Frequently Asked Questions
Can I run a 240V fridge through an inverter in my camper trailer? Technically yes, but you should not. Running a 12V compressor fridge through an inverter loses efficiency twice — 12V DC to 240V AC, then back to 12V DC inside the fridge. Buy a 12V fridge (Engel, ARB, Brass Monkey) and wire it directly. You’ll get 20–30% longer battery runtime for the same cooling.
Will a 1000W inverter run a coffee machine? It depends on the machine. A basic drip-filter coffee maker draws 600–800W and will run on a 1000W inverter comfortably. A fully automatic espresso machine drawing 1,600–1,800W will exceed the 1000W inverter’s capacity and trip the overload protection. For espresso machines, size up to 2000W minimum.
How long will my inverter run from a 100Ah lithium battery? Divide the usable watt-hours by the load. A 100Ah LiFePO4 with 80% usable capacity = 960Wh. A 100W laptop load = 9.6 hours. A 700W microwave = 1.4 hours. A 60W CPAP overnight = 16 hours (with solar top-up recommended). The battery is the constraint, not the inverter.
Do I need a pure sine wave inverter for a CPAP machine? Yes, without exception. CPAP and BiPAP machines contain sensitive electronics and pressure sensors. Modified sine wave power causes them to overheat, produce inaccurate pressures, and fail prematurely. Some CPAP warranties are voided by modified sine wave use. Always use pure sine wave.
Can I leave my inverter on permanently? Most modern pure sine wave inverters have a standby mode that draws only 5–15W when no load is connected. This is negligible. However, if you are not camping (the trailer is in storage), switch the inverter off at the battery — even a 15W standby draw will flatten a 100Ah battery over 6 days.
What inverter size do I need for a small air conditioner? A typical 2kW reverse-cycle split system or caravan-style unit has a startup surge of 2,500–4,000W and a continuous draw of 600–900W. You need a 3000W inverter with a 5000–6000W peak rating, plus a battery bank capable of sustaining the continuous draw (plan on 100Ah LiFePO4 per 1 hour of A/C runtime). Running air conditioning purely from batteries is energy-intensive — most campers who want A/C also run a generator or connect to powered sites.
Putting It All Together
Inverter sizing is not complicated once you apply the formula. The three most common mistakes Australian campers make are: buying a modified sine wave inverter to save $150 (and regretting it when the laptop brick fails), undersizing the inverter and tripping it every time they use the microwave, and neglecting cable sizing which turns the inverter into a heater.
For most couples camping off-grid in a hard-shell teardrop, a 2000W pure sine wave inverter is the right answer. It handles everything except an electric kettle at full simultaneous load, and at $499–750 for a quality KickAss or REDARC unit, it represents excellent value in 2026.
Grey nomads doing extended laps with a CPAP, a coffee machine, and a TV should consider a 3000W unit for the headroom. Weekend campers who only need to charge laptops and run a CPAP can comfortably use a 1000W unit and save $200–400.
Pair your inverter with the right battery and solar system, and you’ll never think about power again. The Breath Ultra and Breath Max ship from our Sydney workshop with lithium batteries and REDARC DC-DC charging ready for exactly this kind of off-grid independence. You add the inverter that suits your 240V load, and the system works.
Ready to spec your complete power setup? Compare all four Breath Trailer models or book a consultation with our team.
Recommended Reading
- Understanding Camper Trailer Solar Systems (Australia) — how panels, MPPT controllers, and battery capacity all work together
- AGM vs Lithium Batteries for Camper Trailers — which battery bank suits your inverter load
- The Ultimate Off-Grid Camper Trailer Setup (Australia) — complete system design beyond just the inverter
- Off-Grid Teardrop Camper Australia — how teardrop owners manage power in the real world
- Breath Trailer Comparison — specs for all four models including standard electrical fit-out