Diesel Generator Buying Guide: Everything You Need To Know

When you are in need of power, you need an option that is not going to let you down and can handle the demands of your power needs. Whether you need to power lights and appliances during a weekend in the woods or need backup in a weather-forced power outage, a diesel generator makes for a great solution.

There is a lot to consider when determining how to select a generator. In order to find the best diesel generator for you, you should pay attention to a few important qualities and specifications. At GeneratorTools, we are happy to be a helping hand along the way.

How Does a Diesel Generator Work?

A diesel generator works similarly to a diesel engine. The engine generates power using a four-stroke cycle, which turns a motor to create an electric current. The four strokes in the cycle are:

• Intake
• Compression
• Power
• Exhaust

Throughout this cycle, air enters the engine cylinder, and a piston compresses the air. Once the air is completely compressed, a fuel injector shoots diesel fuel into the cylinder. The injection of diesel fuel into the compressed air causes immediate combustion, forcing the piston down. When the piston comes back up, it pushes the exhaust gas out of the chamber.

In a diesel engine, compression alone is enough to cause the mixture to combust as the extremely tight compression immediately heats the mixture. The combustion of the air/fuel mixture keeps the piston in motion, turning the crankshaft that spins a motor and creates the electric current.

Diesel vs Gas Generators

Gas generators operate in a similar way to diesel generators. The key difference between the two is that normal gas generators rely on a spark plug to ignite the air/fuel mixture instead of relying on compression alone. While they operate differently, they both are excellent options depending on your needs.

Many people choose a diesel or gas generator because they are efficient and more than capable of powering multiple appliances. However, the final choice comes down to a few key differences.

Diesel Generators Have More Power

Because diesel generators rely on compression for their power output, they are also able to generate more power than gas generators. Diesel generators require that the air is packed together more tightly than with a gas engine. Since the engine is able to compress the air so tightly, it is able to compress more oxygen in each cycle. This higher amount of oxygen leads to a higher power output during combustion.

Diesel generators are often used for commercial purposes because they can handle a much higher power output. These generators are also more able to withstand long-term use compared to gas generators.

Gas Generators Are More Compact

Since gas generators do not need larger engine cylinders for extreme compression of air and fuel, they are usually smaller in size than diesel generators.

You do not always need a powerful generator for every job. In some cases, you may value size over power output. If you need a generator to bring with you to the campsite or tailgate party, and you do not expect much out of it, then a gas generator may be enough.

Diesel Generators Are More Fuel Efficient

One of the first considerations to make when choosing between a diesel generator and a gas generator is their fuel efficiency. After all, a generator’s fuel efficiency determines the power output and, ultimately, how much money you spend on refueling it. The fuel efficiency of these generators often makes them a worthy investment.

Gas Generators Need More Maintenance

One of the largest benefits of a diesel generator is that it needs very little maintenance to keep it running strong. On the other hand, gas generators are not as convenient. Gas generators use a carburetor to blend the air and fuel mixture.

Unfortunately, the carburetor is more likely to fail or malfunction than components in a diesel generator. As a result, gas generators are not quite as reliable as diesel ones.

With a diesel generator, the only maintenance necessary includes regular oil changes as well as fuel and air filter replacements. You should also have your generator regularly inspected by a qualified maintenance professional.

Diesel Generators Cost More

Not only is the upfront cost of a diesel generator higher than a gas generator, but the price of diesel fuel is also higher than regular gasoline. Altogether, you are going to end up spending more on a diesel generator than a gas generator. As a result, your choice of generator will depend on how much value you get for the price.

For smaller jobs, a cheaper gas generator may be more than enough to handle the task. However, if you are planning on using your generator extensively, the higher upfront cost may be worth it. Between the lower maintenance and higher output, diesel generators are more expensive for a reason.

Types of Diesel Generators

Although the mechanics of diesel generators are usually the same, they are several different types with different benefits and capabilities. Because of their specific benefits, you should make special considerations about which would work best for you as the type of generator you decide on will be directly related to your needs. There are three main types of diesel generators.

Portable Generators

Portable generators are exactly as their name describes. These generators are smaller, easier to move, and best suited for transport. They may even have wheels on them to make transporting them easier.

The tradeoff is that the small size of portable generators makes them less powerful and limited in their fuel capacity. As a result, they are better for temporary use rather than long-term use on a property.

Inverter Diesel Generators

Inverter generators are another type of portable generator but with the ability to regulate engine speed and power output. These generators have an internal electronic component that adjusts the engine speed depending on the power needs of the load.

The ability of these generators to regulate their output makes them more fuel efficient. By reducing engine speed based on the amount of power output needed, the generator does not run at continuously high outputs or burn unnecessary fuel.

Their engine efficiency also allows them to operate more quietly. Therefore, inverter generators are the better option when camping or staying in an area with noise restrictions.

Standby Generators

Standby generators are stationary and permanently installed on a property. These generators are the most powerful, have the longest run time, and are the most capable. At the same time, they are also larger than the other types of generators.

These generators are often used to help back up your home or business during a power outage. Some of which are even powerful enough to keep your operations running at full capacity. Standby generators are often capable of running heating systems, air conditioners, and vital appliances like refrigerators. As a result, they can be a huge difference maker in winter storms or hot summer power outages.

What to Consider When Buying a Diesel Generator

The last mistake you want to make when buying a diesel generator is to buy one that cannot power all of your devices. You also do not want to buy a generator that cannot go where you need it to. As you search for the best diesel generator for you, you should consider its power output, size, operation system, fuel efficiency, and more.

Wattage Range

Of course, you buy a generator to generate power, so the most important consideration to make is how much power output it has. Diesel generator power output ranges from 8 kW to a hefty 30 kW. In commercial settings, generators can generate as high as 2,000 kW of power, but they are not entirely common.

When comparing power outputs in your search for a generator, keep in mind that you do not want to run a generator at maximum capacity for an extended period of time. Therefore, you should look at the startup wattage for the appliances that you need and choose a generator that is rated above that amount. For the sake of your generator, it is important that it provides more power than your devices need, not just enough to power them.

Fuel Efficiency

Especially with the increasing costs of fuel, you do not want to spend more on fuel than necessary. Fortunately, when you buy a diesel generator, you can compare the fuel efficiency of different models. Buying a generator with lower fuel efficiency could end up losing you considerable money overall.

As you comb through your options, you should look at how much fuel your generator uses per hour. Generators have different fuel consumption ratings on different loads, so consider what you are going to use your generator for in order to accurately calculate how much fuel you may use. Of course, if you plan on running your generator close to full capacity, you can expect to burn more fuel per hour than if you are running it at only half load.

Fuel Capacity

Not only do generators differ in fuel efficiency, but they also have different tank sizes. Therefore, you should consider your access to fuel and how frequently you are going to need to fill it up.

In instances where generators are going to be frequently running and in areas away from gas stations, it is better to buy a generator with a tank that can hold considerable amounts of fuel. If you are going to be using your diesel generator just a little bit at a time, then a high fuel capacity is not going to be as important.

Generator Size

Whether you are looking for a portable generator or standby generator, size and weight are two important factors. For a portable generator, you will want to be sure that you will be able to carry it in your vehicle and have enough room for the rest of your camping or tailgating gear.

For a standby generator, you should know the size so that you know how big its footprint will be and how much space it will take up in your yard, warehouse, or another area. Since standby generators often need a concrete foundation installed, the size of the generator can also affect installation costs, so it helps to know what you are getting into.

Weight is also important to look into before purchase. Even generators listed as portable can be several hundred pounds, so you should make sure to look through all of the specifications before making your final decision.

Control System

A control and management system provides important information about your generator and can make it easier to operate. Some generators are more advanced in their control management systems than others, with the ability to highlight performance issues like low fuel or mechanical problems. More advanced systems even have an automatic shut-off system in the event of serious concerns, like low oil pressure, high system temperatures, and engine operation issues.

A control system is especially important in commercial applications and when handling heavy loads. As you weigh your options, you should choose a diesel generator with a management system that is easy to use and provides information that you think you may need.

Power Management System

Many generators now feature a power management system, which provides additional information about power flows through the unit. Power management systems provide the ability to kick on automatically during a power outage and can also control power output depending on the priority of the loads on the unit. This system prevents the generator from overloading when powering larger appliances.

If you are powering larger appliances, then you should consider a generator with a power management system.

Starting Method

Generators can use different methods for starting. Some of the mechanisms include a key, a push-to-start button, and a remote start. Some generators are even equipped with automatic start, allowing them to power on as soon as a power outage is detected.

For many people, the difference between a button and a key does not make a significant difference. However, remote start and automatic start capability can provide a large advantage. For example, if a storm causes a power outage in the middle of the night, then remote start allows you to get the power up and running without leaving the house. An automatic start system is even more convenient, kicking on as soon as an outage is detected.

Modular Capability

In commercial applications or to back up larger houses, a single generator is not always enough. Additional generators that run in a parallel or modular sequence can provide extra power or kick on if the primary generator fails.

In the event that you may want to scale up in the future, you should pay attention to whether the generator you buy now will be able to handle a parallel set. Some generators make the process simple enough to install in a matter of minutes, while others are not capable of linking with other generators at all. Therefore, modular capability should play a role in your decision-making.

How Big of a Generator Do I Need?

The size of the diesel generator you need depends on the size of the job that you need to be done. If you are using a generator while you are camping to power a few devices, like a coffee maker, some lights, and cell phone chargers, then you can get away with a much smaller generator.

However, if you are buying a generator because you live in an area with frequent power outages, then you are more likely to need a larger standby generator. Ultimately, a larger size equals greater power output, so if you have big power needs, you should prepare to have the storage for a larger generator.

Your size needs will also depend on whether you need a portable or stationary generator. A portable generator is clearly the much better choice for situations like camping, tailgating, or overlapping.

On the other hand, to power operations at your home or business or for backup power during storms, a larger stationary generator is fine. In fact, if you are not moving your generator, it often makes more sense to buy a larger one since it will likely have a greater power output.

How Much Does a Diesel Generator Cost?

Diesel generators can fall into a wide price range. Typically, you can find a diesel generator priced between $800 and $20,000. Of course, more powerful generators are going to cost more than those with lower power outputs. Diesel generator prices depend on a few key factors, like:

• Generator size
• Power output
• Type of generator
• Fuel capacity

If you are planning on having a diesel generator installed to power your home, then you will also need to consider installation costs. A standby home generator can cost between $500 and $5,000 to install. The installation price includes the labor cost for connecting the generator to the gas line, a concrete foundation for the generator to sit on, a permit if needed for the city or HOA, and installing a transfer switch if necessary.

Top Diesel Generator Brands

In your search for the best diesel generator, you will come across a long list of brands. Some of the top brands include:

• Cummins
• DeWalt
• Duromax
• Generac
• Ryobi
• Westinghouse

Many brands have their own reputations, which could influence your choice. To learn more about each of the brands, their benefits, and their reviews, explore the GeneratorTools brand guide.

Trust GeneratorTools in Your Search

Altogether, diesel generators are fuel efficient, powerful, and capable of taking on some tall tasks. However, there are several considerations to weigh as you explore options for a diesel generator, and the industry is constantly seeing new developments. As you look for the right generator to fit your needs, GeneratorTools is here to help.

At GeneratorTools.com, you can find a complete buyer’s guide for diesel and gas generators. We provide a breakdown of all the industry’s top brands so that you know what to expect from each one. We also have an extensive list of reviews and guides to help you better understand what to look for and how to compare different generators. Explore our guide for yourself, and simplify your search.