How long can your generator sit unused? Short answer: not long without trouble. Leave it idle too long and you'll be facing stale fuel, seized parts, or a dead battery. This article breaks it down—how long you’ve really got, how to store it right, and how to keep it ready for when the power cuts out.

The Hidden Dangers of an Unused Generator

Letting your generator sit untouched for weeks or months might seem harmless. But under the hood, things are quietly going downhill.

The Problem with Fuel Degradation

Fuel, especially ethanol-blended petrol like E10, starts to degrade within 30 days. Left untreated, it turns to varnish or sludge, clogging the carburettor and making your generator harder to start. In hot Aussie conditions, this process speeds up. If you’ve ever pulled the cord for five minutes with no response, you’ve likely met stale fuel. This is a common issue for petrol generators that aren't used regularly.

Why Engine Parts Seize

Engines like to move. When your generator sits idle, the internal parts lose their lubrication. Over time, this can cause them to seize up—literally freeze in place. Think of it like leaving your bike out in the rain, untouched. Come summer, the wheels won’t turn without a fight. Maintenance is even more critical for large generators where engine repairs are significantly more expensive.

The Dangers of Rust and Corrosion

Australia’s humidity, especially near the coast, is a silent killer. Moisture seeps into every crevice, rusting metal parts and corroding sensitive components. Salt air makes it worse. A rusted generator isn’t just ugly—it’s unreliable when you need it most. Keep this in mind if you own portable generators stored in garden sheds.

How the Battery Drains

If your generator has an electric start, the battery won’t hold a charge forever. Left untouched, it gradually drains—even when the unit is off. Come storm season, you might find yourself with a perfectly good generator and a dead battery. A quick top-up every month with a 12v portable battery or charger can save a lot of swearing later.

Exercising Your Generator: The Key to Reliability

A generator isn’t like a fine wine—it doesn’t get better with age. Regular use is what keeps it ready to go.

Creating a Regular Maintenance Schedule for Your Generator

Set a recurring reminder on your phone or stick a note in the shed. Every two weeks, give your generator a short run. Regular exercise keeps the internals moving, the fuel system clean, and problems from building up unnoticed. Whether it's one of the premium Westinghouse generators or a budget model, they all need exercise.

Why You Should "Exercise" a Generator

Running your generator every few weeks helps prevent fuel breakdown and keeps seals lubricated. It’s like taking your car for a spin after it’s been parked up for a while. Letting it idle occasionally helps the engine stay in good nick and avoids surprises down the track.

How Often and for How Long to Run Your Generator

Aim for 5–10 minutes every fortnight. It doesn’t need to be a full workout—just enough to keep it in shape. If it’s been stored for a while, let it run for a bit longer to ensure everything is functioning smoothly. Owners of diesel generators should pay extra attention as diesel can grow algae if left stagnant too long.

Running the Generator with a Load vs. Without a Load

Running your generator under load (e.g. plugged into a small appliance) is better than idling. It simulates real-world use and puts the electrical system to work. Just don’t overload it—stick to a modest draw like a fan or light. This is good practice for all power generators.

Preparing Your Generator for Long-Term Storage

If you’re not planning to use your generator for a few months, it needs more than a dusty corner in the shed.

Fuel Management for Your Stored Generator

Leaving fuel in the tank is risky business. Ethanol-based petrol absorbs moisture and deteriorates quickly, especially in heat. You’ve got two options: drain it or stabilise it.

The "Drain It Dry" Method

For long-term storage, draining is best. Let the generator cool, shut off the fuel valve, and drain the tank and carburettor completely. This prevents gumming and protects the engine from moisture-related damage. Just make sure to run it dry, so no fuel is left in the lines. If this feels like too much work, you might prefer portable power stations, which require much less mechanical upkeep.

The Best Fuel Stabilizer

If you plan to use your generator again within 6–12 months, a fuel stabiliser is your best mate. Brands like Penrite, STA-BIL, and Lucas work well. Mix it with fresh petrol, fill the tank, and run the engine for 10 minutes so it circulates through the system. This keeps fuel from breaking down and avoids clogs.

A Complete Checklist for Your Generator

Before storing your generator, tick off the following to ensure it's ready next time.

Changing Your Generator's Oil

Old oil can become acidic and damage internal parts. Change the oil before storage—especially if it’s close to the 100-hour mark. Use manufacturer-recommended oil and keep a spare bottle on hand. Clean oil means less risk of corrosion inside the engine. This is standard for most generators for home use.

Engine "Fogging" and Its Importance

For generators stored over winter, fogging oil adds a protective layer inside the engine. Spray it into the air intake while the engine is running, then shut it off. This helps prevent corrosion and dry starts when you fire it up again.

Storing Your Generator: Location and Environment

Pick a dry, cool spot with plenty of airflow. Avoid hot sheds or damp garages. If you’re near the coast, protect it from salty air—use a cover or store it indoors. And make sure pests can’t nest inside—mice love quiet engines. If you are worried about fuel shelf life, consider the price of generators that run on LPG or battery power as alternatives.

Done right, storage doesn’t just preserve your generator—it guarantees it’s ready to go when you need it. Whether it’s a blackout, storm, or weekend away, a well-maintained generator is your silent insurance policy.

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• How to Plug a Generator Into a Caravan?
• What Is the Biggest Risk Associated With Portable Generators?
• How Do I Reset a Generator Circuit Breaker?
• How Do I Test Battery Voltage in Electric-Start Generators?
• Can Thermal Cameras Detect Generator Faults?

Timothy Jagger

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About the author:
“What I love most about getting outdoors is switching off and hitting reset. I used to spend my weekends legging it out from under a roof—now I help others do the same.”