Generator for a Campervan: Do You Need One and What to Buy

A generator gives a campervan unlimited electrical autonomy — you can charge your batteries in any weather, without hook-up. But generators are loud, need fuel, and require careful use. Here is an honest guide to whether you need one and what to buy.

When a generator makes sense

Winter van life in the UK: Solar output in December and January in the UK is minimal (often under 1 kWh/day even with 200W of panels). A generator provides reliable battery charging when solar is insufficient.

Remote locations without hook-up: Wild camping for extended periods where driving is not generating enough alternator charge.

High-consumption workloads: Running power tools, mains appliances, or keeping a large battery bank topped up in overcast conditions.

As a backup: Even a solar-heavy system benefits from having a generator as a rarely-used emergency backup.

When a generator is probably overkill

• If you spend most nights at campsites with hook-up
• If you drive regularly (alternator via DC-DC charger provides substantial charging)
• If your loads are modest (fridge, lights, phone — 60–80Ah/day), where a larger battery bank + more solar is simpler than a generator

Types of generators

Conventional petrol generators

Traditional generators with a direct engine-to-alternator drive. Output is not pure sine wave at rated frequency — the frequency varies with load. Do not use conventional generators to charge sensitive electronics or run appliances that require stable frequency.

Not recommended for campervans except for running purely resistive loads (battery charger, kettle). Too noisy, too heavy, output quality too poor for modern electronics.

Inverter generators

An inverter generator produces DC, then uses an inverter to produce stable 230V pure sine wave output at a consistent frequency, regardless of engine load. The engine speed varies with load, making them significantly quieter and more fuel-efficient than conventional generators.

These are the right choice for campervans. Common models:

What size generator?

For battery charging via a mains charger:

• A 25A mains charger draws ~375W from the generator
• A 40A mains charger draws ~600W
• Any 2,000W generator can comfortably run these, leaving headroom for other loads

For running appliances directly from the generator:

• Add up the wattage of everything you plan to run simultaneously
• A 2,000W generator handles most campervan needs: kettle, laptop, charger

1,000W generators are available (Honda EU10i, ~8kg) — excellent if you only need to charge batteries and not run high-wattage appliances.

How to charge your leisure battery from a generator

Via a mains battery charger: Connect the generator 230V output to your van's mains input (or use an extension lead to a Victron Blue Smart or similar mains charger). This is the standard approach.

Via the van's hook-up inlet: If your van has a 230V shore power inlet, connect the generator to it with a 16A extension lead. The van's existing mains charger and 230V circuits work normally.

Charge time example: Generator + 30A charger charging a 200Ah LiFePO4 from 20% to full: ~1.5 hours. Fuel use on a 2,000W inverter generator at this load: approximately 0.5 litres per hour.

Generator etiquette and rules

• Many campsites prohibit generator use or restrict to certain hours
• Wild camping with a generator disturbs wildlife and other people
• Run generators well away from sleeping areas — exhaust fumes (including CO) are dangerous indoors and close to windows
• Never run a generator inside a closed vehicle or building

FAQ

Can I charge a LiFePO4 battery directly from a generator without a battery charger?

Only if the generator has a DC output (some models have 12V DC cigarette lighter outputs). These are typically limited to 8A — useful for trickle charging but very slow. Use a proper 230V mains charger for full charging speed.

How much petrol does a generator use?

An inverter generator running at half load (1,000W from a 2,000W model) typically uses 0.5–0.8 litres per hour. A full tank (3–4 litres) gives 4–6 hours of charging.

Is a generator safe to use in rain?

Most inverter generators are not waterproof — they need a dry operating environment. Use a generator tent or canopy to protect from rain. Always keep the exhaust and air inlet clear of any enclosure.