A small generator is a useful backup when solar isn't cutting it — but only if it's matched to what you actually run. Buy the wrong one and you'll trip the aircon's start-up surge, overload the unit, or carry dead weight you never use. Here's how to size, choose and use one properly.

When You Actually Need One

Most Mars owners with current spec (lithium + solar + sometimes inverter aircon) don't need a generator at all in normal conditions. A generator earns its weight when:

• You camp off-grid for extended periods in shaded/winter sites where solar can't keep up
• You want to run high-draw 240V appliances (aircon, microwave, kettle) without burning battery
• You're at a free camp for several days and want to recharge without driving
• You want a backup for medical equipment that has to run on 240V

If most of your camping is at powered sites or short off-grid trips with solar, you probably don't need one.

Sizing — The Critical Decision

Watts Out vs Watts You Need

• Running watts — what an appliance draws continuously
• Surge watts — what it draws for a few seconds at start-up (especially anything with a motor: aircon compressor, fridge, microwave, water pump)

Surge can be 2–3x running watts. A 2000W generator that "can run a 1500W aircon" might fail when the aircon's compressor kicks in at 4000W surge for a half-second.

Typical Loads in a Mars Caravan

Sizing Guide

• 1000W (1kVA) — too small for most caravan use. Suitable for battery charging and small appliances only.
• 2000W (2kVA) — most common. Runs the battery charger + most appliances. May struggle with aircon surge unless aircon has soft start.
• 2400–2800W — handles aircon surge reliably on most setups. The sweet spot for full van support.
• 3000W+ — heavy and overkill for most. Twin-aircon setups or commercial use.

What to Buy — Categories

Inverter Generators (What You Want)

• Quiet — typically 55–65 dB at 7m (similar to normal conversation)
• Produce pure sine wave (safe for sensitive electronics — modern fridges, chargers, induction cooktops)
• Variable engine speed — uses less fuel under light loads
• Light and portable for the wattage

Traditional Generators (What You Don't Want for Caravan Use)

• Loud (often 80+ dB) — you'll be unpopular in any camp
• Modified sine wave — risky for inverter-driven appliances and lithium chargers
• Run at full RPM regardless of load — heavy fuel use
• Heavier and larger

Buy an inverter generator for caravan use. Always.

Brand Categories

Premium

Honda EU22i / EU30iS, Yamaha EF2000iS — quietest, most reliable, hold value, more expensive ($1500–$3000+).

Mid-Range

Briggs & Stratton P-series, Cromtech Outback, Gentech, Pramac — solid performance, more affordable ($800–$1500). Most caravan buyers land here.

Budget

Kings, Genpower, no-name inverter generators ($400–$800). Work, but expect shorter lifespan, more failures, more noise. Fine for occasional use.

Carrying a Generator on Your Van

Generator Slide

Many Mars vans have an optional generator slide — a slide-out tray on the rear bumper or under-tray that holds the generator securely for travel. Best option if you carry a generator regularly:

• Generator is contained, ventilated and secure during travel
• Easy to slide out and run
• Slide can lock

In the Tow Vehicle

Ute tray, canopy, boot — works for occasional use. Heavy item, eats payload. Fuel smell can permeate the tow vehicle.

Never Inside the Van

Petrol vapours in an enclosed space are dangerous. Generators stored inside is a fire and CO risk even when not running. Always external storage.

Fuel

• Most inverter generators run on unleaded.
• Some run on dual fuel (unleaded + LPG bottle), which has advantages — LPG burns cleaner, longer storage stability, and you already carry LPG.
• Carry stabilised fuel if storing for long periods (servo fuel deteriorates within ~3 months).
• Plan fuel — a 2kVA inverter generator typically runs 4–10 hours on its built-in tank depending on load.

Running the Generator

Connection to the Van

1. Connect a proper 15A caravan power lead from the generator's 15A outlet to the van's 240V inlet.
2. Confirm the generator is running cleanly (warmed up, stable RPM) before turning anything on inside the van.
3. Turn on the van's 240V system as you would on shore power.
4. Start loads one at a time — don't switch on three high-draw items simultaneously.

Charging the Battery While Running Other Things

The battery charger automatically pulls 240V from the generator when available. This means while the generator runs, you're charging the lithium and running appliances. Productive use of the run time.

Camp Etiquette

• Most caravan parks ban generators (they have mains for you to use)
• Most free camps allow generators but with quiet hours (typically 8pm–8am)
• Run during socially reasonable hours (mid-morning to mid-afternoon)
• Position the generator away from neighbouring vans — exhaust and noise both
• National park rules vary — check signage

Safety

• Never run inside the van. CO can build up to lethal levels in minutes.
• Never run with the van's window open near the exhaust. Same reason.
• Ground the generator if its manual specifies — most inverter generators don't require external grounding.
• Don't refuel a hot generator. Wait for it to cool.
• Don't run in heavy rain. Most aren't weather-sealed.
• Cable to van should be a proper 15A caravan lead, not an indoor extension.

What to Maintain

• Run fuel through every 1–2 months when not in use (or use stabiliser)
• Change engine oil annually or per the manual
• Clean air filter regularly
• Check spark plug annually
• Drain fuel before long storage

Service manuals are model-specific — follow your generator's instructions.

The Right Generator Decision

For most Mars owners considering a generator:

• 2.4kVA inverter generator, name-brand mid-range handles all normal caravan loads including aircon surge.
• Stored on a slide on the back of the van when needed.
• Used for occasional charging and aircon support, not as the primary power source.

If you'll only use it for occasional battery charging at quiet remote camps, 2kVA is plenty. If you'll regularly run aircon from it, go 2.4kVA+ with confirmed aircon-surge compatibility (or aircon with built-in soft start).

Related: How Your Mars Solar System Works · Cold Weather Camping