Buying Guide to Selecting the Right Surplus Generator

When the lights go out, or you're miles from the nearest power outlet, a reliable generator isn't just a convenience—it's peace of mind. But wading through options can feel overwhelming, especially when you start looking at the robust, often cost-effective world of surplus generators. This Buying Guide to Selecting the Right Surplus Generator is designed to cut through the jargon, giving you the trusted insights you need to make an informed decision and power your world, whether it's your home during an outage, your RV on a cross-country adventure, or your tools at a remote job site.

At a Glance: Your Surplus Generator Selection Checklist

Assess Your Power Needs First: List all devices you want to run, noting their starting and running watts. This is non-negotiable.
Match Generator Type to Use: Standby for whole-home automatic backup, portable for versatility, inverter for quiet and sensitive electronics, solar for clean, silent power.
Consider Fuel Type: Balance availability, cost, storage, and efficiency for your primary use (gasoline, propane, diesel, natural gas, solar).
Prioritize Safety Features: Look for automatic CO shutoff, low-oil shutoff, and plan for a transfer switch (professional installation is key).
Budget Beyond the Price Tag: Account for potential installation costs, fuel, maintenance, and essential accessories.
Approach Surplus Wisely: Understand the trade-offs of potentially older, heavy-duty units versus new models, factoring in condition, parts availability, and your comfort with maintenance.

Why a Generator Isn't a Luxury, It's a Necessity

Power outages are increasingly common, driven by everything from severe weather to aging infrastructure. Beyond emergencies, generators unlock off-grid living, make RV trips more comfortable, and ensure job sites stay productive. They're more than just a motor; they're your connection to light, communication, refrigeration, and comfort when grid power isn't an option.
While new generators offer warranties and the latest tech, surplus generators—often retired from industrial, commercial, or even military applications—present a unique value proposition. They're typically built to higher specifications, designed for durability under demanding conditions, and can be significantly more affordable upfront. However, selecting the right surplus unit requires a discerning eye and a solid understanding of generator fundamentals.

Pinpointing Your Power Needs: The Golden Rule of Generator Shopping

Before you even think about brands or fuel types, you must accurately calculate how much power you actually need. This critical step prevents both under-powering (leaving you in the dark) and overspending on excess capacity.
Every appliance has two main power ratings:

Starting Watts (or Surge Watts): This is the brief, initial burst of power an appliance needs to kick on, especially those with motors like refrigerators, pumps, or air conditioners. It can be several times higher than the running watts.
Running Watts (or Rated Watts): This is the continuous power an appliance draws once it's operating normally.
For battery-powered portable power stations and solar generators, you'll look at:
Watt-hour (Wh) Capacity: This indicates the total stored energy, essentially how long a device can run. For example, a 2,400 Wh capacity means it can deliver 100 watts for 24 hours.
Peak Output: Similar to starting watts, this is the maximum surge of power the station can briefly provide.
How to Calculate Your Needs:

List Everything: Make a comprehensive list of all the devices and appliances you absolutely need to power simultaneously during an outage or off-grid scenario.
Find the Watts: For each item, look for its starting and running wattages. This information is usually on a label on the appliance itself, in the owner's manual, or easily found online.
Sum Running Watts: Add up the running watts for all the devices you plan to operate at the same time. This gives you your total continuous power requirement.
Identify Highest Starting Watts: Find the single appliance on your list that has the highest starting wattage.
Calculate Generator Size: Add your total running watts from step 3 to the highest single starting watts from step 4. This sum is your target "surge" or "peak" wattage for the generator. Your generator's running watt rating should be at least equal to your total running watts from step 3.
Example Scenario:
You need to run a refrigerator (600 running, 1800 starting), some lights (500 running), a TV (200 running), and charge phones (100 running).

Total Running Watts: 600 + 500 + 200 + 100 = 1400 watts.
Highest Starting Watts: Refrigerator at 1800 watts.
Required Generator Size: You need a generator that can deliver at least 1400 running watts and have a surge capacity of at least (1400 - 600) + 1800 = 2600 watts (assuming the refrigerator is the biggest draw and starts independently). A 3000-watt portable generator would likely suffice.
For whole-home standby systems, a 20kW unit is often sufficient for most residential devices, though a professional assessment is always recommended.

Decoding Generator Types: Which One Powers Your World?

Generators come in various forms, each designed for specific applications. Understanding these distinctions is crucial, especially when evaluating surplus options, which might lean towards older, more traditional designs.

1. Home Standby Generators

These are the heavyweights of home backup. Hardwired into your home's electrical system by a professional, standby generators connect via an automatic transfer switch. When grid power fails, they sense the outage and kick on automatically, often powering your entire home.

Pros: Seamless, automatic operation; can power entire homes; typically natural gas or propane (limitless fuel source if connected); heavy-duty and long-lasting.
Cons: High upfront cost including significant professional installation; permanent fixture; not portable.
Surplus Context: You might find older, very robust industrial standby units, but their condition and compatibility with residential systems need thorough professional review.

2. Portable Generators

The most common type for homeowners, campers, and job sites, portable generators offer flexibility. They run on gasoline (most common) or sometimes propane, and are designed to be moved.

Pros: Versatile; relatively affordable; can power multiple devices; good for camping, tailgating, and temporary home backup (using extension cords or a manual transfer switch).
Cons: Can be noisy; less fuel-efficient than inverters; require careful refueling and ventilation.
Surplus Context: Many surplus generators, especially military ones, fall into this category, often built with extreme durability in mind. Their robustness can be a huge advantage, but weight and noise might be higher.

3. Inverter Generators

A sophisticated type of portable generator, inverters produce AC power, then convert it to DC, and then "invert" it back to clean AC power. This allows them to adapt their engine speed to the power demand, leading to significant benefits:

Pros: Fuel-efficient; significantly quieter than traditional portables (especially closed-frame models, often called "SUPER QUIET"); safe for sensitive electronics (laptops, phones, medical equipment) due to stable, "clean" power output; often lighter. Many newer models feature automatic CO shutoff (e.g., CO Secure Technology).
Cons: Generally more expensive than traditional portable generators; lower maximum power output than some larger traditional portables.
Surplus Context: Inverter technology is relatively newer, so finding true surplus inverter generators might be less common or for a higher price. If you do, they’re usually excellent finds. Open-frame inverters exist, offering a quieter experience than traditional generators but louder than closed-frame inverters.

4. Solar Generators / Battery-Powered Portable Power Stations

Operating more like large, portable batteries, these units store energy that can be charged via wall outlets, car chargers, or solar panels. They provide pre-stored energy (measured in watt-hours).

Pros: Completely silent; zero emissions (no gas or propane needed); lightweight; ideal for sensitive electronics; low maintenance.
Cons: Limited runtimes and output compared to fuel-based generators; dependent on sunlight for recharging (for solar models); higher upfront cost for significant capacity.
Surplus Context: Unlikely to find "surplus" units in the traditional sense, as these are typically consumer-grade electronics. However, you might find surplus industrial-grade battery banks or solar panels that could be integrated into a DIY system.

5. Traditional Generators

These are the workhorses – often open-frame, robust, and designed for reliability and raw power output. They run at a constant engine speed regardless of load.

Pros: Generally more affordable than inverter generators for comparable power; straightforward design; powerful.
Cons: Much louder; less fuel-efficient; produce "dirty" power that can damage sensitive electronics; should not be used in enclosed areas due to carbon monoxide.
Surplus Context: Many older surplus units, especially those from industrial or military applications, fall into this category. They are often incredibly durable but come with the noise and fuel efficiency drawbacks.

AC vs. DC Generators: A Quick Clarification

AC (Alternating Current) Units: The vast majority of generators you'll encounter for home, RV, or job site use are AC units. They produce the same type of power your wall outlets provide, suitable for most household appliances.
DC (Direct Current) Units: Primarily used for charging batteries (e.g., in RVs or marine applications). For general appliance use, DC power needs to be converted to AC via an inverter, which is why battery-powered stations inherently have an inverter built-in. Most fuel-powered generators produce AC directly.

Fueling Your Power: Options and Considerations

The fuel source you choose for your generator significantly impacts its convenience, operational costs, and long-term storage needs.

Gasoline:
Pros: Most common fuel for portable generators, widely available.
Cons: Has a relatively short shelf life (months, not years) and degrades, requiring fuel stabilizers for storage. Highly flammable.
Propane:
Pros: Clean-burning, longer storage life than gasoline, readily available in tanks, common for standby units. Lower fire hazard than gasoline.
Cons: Less energy-dense than gasoline or diesel, meaning slightly less power output and faster consumption for the same load. Requires tanks, which can be bulky.
Diesel:
Pros: Popular for portable and industrial generators (often found in surplus units). Longer storage life than gasoline, very durable engines, lower fire hazard than gasoline. Extremely fuel-efficient.
Cons: Diesel engines can be louder and heavier; diesel fuel can gel in extreme cold without additives; typically higher emissions than propane or natural gas.
Natural Gas:
Pros: Exclusively for standby generators, tied into your home's gas line. Offers a virtually limitless fuel source during an outage, eliminating the need for refueling.
Cons: Only for permanent installations; less energy-efficient (meaning a larger engine is needed for the same power output) and less common in surplus units.
Solar:
Pros: Clean, free energy from the sun. Silent operation, zero emissions.
Cons: Dependent on sunlight; limited power output and runtime without sufficient battery backup. A power reserve (battery) is essential to store energy for use when the sun isn't shining.
When considering a surplus generator, especially diesel units, factor in the availability and cost of that specific fuel in your area, and the ease of sourcing it during an emergency.

The Heart of Safety: Transfer Switches and CO Awareness

Generator safety is paramount, not an afterthought. Improper use can lead to electrocution, fire, or fatal carbon monoxide poisoning.

Transfer Switches: Connecting Safely

A transfer switch is a device that safely connects your generator to your home's circuit panel. It acts as a gatekeeper, preventing "backfeeding"—sending electricity back into the utility grid. Backfeeding can electrocute utility workers and damage your generator or appliances.

Automatic Transfer Switches (ATS): Found in standby generators, these detect power outages and automatically switch your home's power from the grid to the generator, and back again when grid power returns. Professional installation is mandatory.
Manual Transfer Switches (MTS): For portable generators, these require manual intervention at your electrical panel to switch between grid and generator power. Again, professional installation is crucial.
Without a Transfer Switch: You must use properly rated, heavy-duty outdoor extension cords to power individual devices directly from the generator. Never plug a generator directly into a wall outlet (this is backfeeding).

The Silent Killer: Carbon Monoxide (CO)

Gasoline, propane, and diesel generators produce carbon monoxide, an odorless, colorless, and lethal gas. Operating these generators in enclosed spaces—garages, basements, sheds—is extremely dangerous and can be fatal within minutes.

The 20-Foot Rule: Always operate gas, propane, or diesel generators at least 20 feet away from your home, windows, doors, and intake vents. Position the exhaust away from any structures.
Automatic CO Shutoff: Many newer portable generators (like those with CO Secure technology) feature this life-saving function, which automatically shuts down the unit if dangerous levels of CO are detected. Prioritize this feature if buying new.
Carbon Monoxide Detectors: Install battery-operated CO detectors with alarms in your home as a critical backup, especially near sleeping areas.
Other Critical Safety Measures:
Read the Manual: This is your primary guide to safe operation and maintenance.
Fuel Stabilizer: Use a fuel stabilizer when storing gasoline to prevent degradation and keep your generator ready.
Refuel Safely: Never refuel a hot or running generator, or one near warm objects. Spill gasoline on a hot engine, and you have an immediate fire risk.
Proper Placement: Keep generators at least 5 feet from surrounding surfaces to ensure adequate ventilation and reduce fire risk.

Beyond the Basics: Essential Features to Look For

While power output and fuel type are primary considerations, certain features enhance convenience, safety, and longevity, especially when evaluating a surplus unit where features might vary widely.

Automatic CO Shutoff: (Reiterating for emphasis) This is a must-have safety feature in any newer fuel-powered generator. If you’re looking at older surplus models, you’ll need to be extra vigilant about CO safety protocols.
Electric Start: Say goodbye to wrestling with a pull cord. Electric start allows you to fire up the generator with a simple switch, remote, or push button. This often requires a small battery.
Low-Oil Shutoff: This feature automatically shuts down the generator if the oil level drops too low, preventing potentially catastrophic engine damage.
Fuel Gauge: Essential for monitoring fuel levels and knowing when to refuel. Seems simple, but not all older models have them.
Noise Level: Measured in decibels (dBA). Quieter generators operate around 50-60 dBA (like a normal conversation), while louder ones can hit 90-100 dBA (like a lawnmower). Closed-frame inverter generators are generally the quietest. For camping or close-quarter use, noise is a major factor.
Run Time: This tells you how long a generator can operate on a single tank of fuel at a given load. Higher loads mean shorter run times. Consider your expected usage duration.

Budgeting Your Backup: Understanding Generator Costs

The cost of a generator isn't just its purchase price. Installation, fuel, maintenance, and accessories all contribute to the total investment.

Standby Generators: These come with the highest overall cost. Product prices start around $3,000, but professional installation can add thousands more. Factors like property specifics, placement, necessary electrical panel upgrades, or the need to run new natural gas/propane lines can significantly inflate the bill.
Portable Generators: These have more fixed product prices, ranging from a few hundred dollars for basic models to over $2,500 for high-end inverter or large dual-fuel units. Their cost primarily depends on power output and fuel type.
When considering a surplus generator, the upfront purchase price might be remarkably low. However, you must factor in potential hidden costs:
Refurbishment/Repairs: Older units may need new parts, carburetor cleaning, or electrical repairs.
Shipping/Transport: Surplus units can be heavy and bulky.
Professional Inspection: Essential to ensure an older unit is safe and functional, especially if it’s an industrial model.
Lack of Warranty: Most surplus units are sold "as-is."
Parts Availability: Can be a challenge for very old or obscure models.

Navigating the World of Surplus Generators

The term "surplus generator" typically refers to units that are no longer needed by their original owner, often military, government, or large industrial entities. These aren't your typical consumer-grade generators.
What Makes Them Different?

Built to Last: Many surplus generators, especially military ones, are engineered for extreme durability, rugged environments, and heavy-duty use. They often feature robust frames, larger engines, and simpler, more repairable components.
Cost-Effective: Their primary appeal is often a significantly lower price point compared to buying a new generator with similar power output and build quality.
Potential for Unique Features: Some military surplus units might come with specialized features like blackout switches or hardened components not found in commercial models.
Challenges and Considerations for Surplus:
Condition is Key: Unlike new generators, condition can vary wildly. Some might be barely used, others heavily worn. Thorough inspection is non-negotiable. Look for rust, cracked hoses, evidence of leaks, and engine health.
Maintenance & Parts: Finding replacement parts for older, specialized surplus models can be a significant hurdle. You might need to be comfortable with mechanical work or have a trusted technician.
Fuel Type & Efficiency: Older surplus units, particularly diesel models, might be less fuel-efficient and louder than modern equivalents.
Weight & Portability: Many surplus generators, especially those designed for industrial or military use, are much heavier and less portable than typical consumer-grade portables. You'll likely need a wheel kit or heavy-duty transport.
Documentation: Owner's manuals or service records might be missing, making maintenance and troubleshooting more challenging.
Safety Features: Older surplus units will almost certainly lack modern safety features like automatic CO shutoff.
To dive deeper into the specifics of sourcing and evaluating these unique options, and to understand the nuances of what makes them stand out, check out Your guide to military surplus generators. It’s an invaluable resource for anyone considering this path.

Putting It All Together: Your Selection Checklist

To distill all this information into an actionable plan, use this checklist when you're ready to evaluate potential surplus generators:

Reconfirm Your Power Needs: Have your running and starting wattages clear. Don't guess.
Define Your Primary Use: Is it for occasional home backup, frequent camping, or a demanding job site? This drives generator type.
Choose Your Fuel Wisely: Consider availability, cost, storage, and environmental impact.
Inspect Condition Thoroughly (for surplus): If buying in person, start it up. Listen to the engine. Check for fluid leaks, frayed wiring, and structural damage. If buying online, demand detailed photos and ask probing questions about service history.
Prioritize Safety: Plan for a transfer switch. Ensure you have CO detectors. If the surplus unit lacks modern safety features like auto-CO shutoff, commit to strict operational protocols.
Assess Noise Levels: If noise is a concern, lean towards inverter models or be prepared for the rumble of traditional units.
Consider Portability & Weight: Can you realistically move the generator where you need it? Do you need a wheel kit?
Budget Beyond the Purchase: Factor in potential repairs, maintenance, fuel, and accessories.
Research Parts Availability: Especially for older or military surplus units, check if common wear parts (filters, spark plugs, belts) are still manufactured or readily available.

Maintaining Your Investment: Tips for Longevity

Once you've selected your generator, proper maintenance ensures it's ready when you need it and lasts for years.

Regular Exercise: Run your generator under a moderate load for 20-30 minutes every month or two. This lubricates components, circulates fuel, and helps ensure it will start when truly needed.
Fuel Management: For gasoline generators, always use fresh fuel. If storing for more than a month, add a fuel stabilizer or drain the carburetor and fuel tank.
Oil Changes: Follow the manufacturer's recommended oil change schedule, typically every 50-100 hours of operation or annually.
Air Filter: Clean or replace the air filter regularly, especially if operating in dusty conditions.
Spark Plugs: Check and replace spark plugs according to the manual for optimal ignition.
Cleanliness: Keep the generator clean and free of debris, especially around cooling fins and air intakes.

Don't Forget the Gear: Essential Accessories

A generator is only part of the equation. These accessories will enhance its safety, usability, and longevity:

Carbon Monoxide Alarms: Absolutely critical for safety when operating any fuel-powered generator.
Wheel Kits: Many open-frame portable generators (and most surplus units) benefit greatly from a robust wheel kit for easier transport.
Batteries: If your generator has an electric start, ensure its battery is charged and in good condition.
Generator Adapters: Especially for RVs, you might need specific adapter cords to match your generator's output to your RV's input.
Gas Cans: Properly rated, spill-proof gas cans for safe fuel storage and transport.
Engine Oil & Filters: Keep spares on hand for regular maintenance.
Fuel Stabilizer: Essential for gasoline generators during storage.
Heavy-Duty Extension Cords: Rated for outdoor use and sufficient gauge for the amperage they will carry.
Power Strips with Surge Protection: For connecting multiple smaller devices safely.
Generator Cover: Protects your investment from the elements.

Your Power, Your Peace of Mind

Selecting the right generator, especially venturing into the world of surplus, is a journey of careful consideration. By understanding your power needs, the different types and their nuances, fuel options, and non-negotiable safety practices, you empower yourself to make a confident choice. A well-chosen surplus generator can be a robust, cost-effective ally, ready to deliver dependable power when you need it most. Arm yourself with knowledge, inspect with a critical eye, and invest in the accessories that complete your power solution. The peace of mind that comes with reliable backup power is truly priceless.