Understanding the Role of an APU (Auxiliary Power Unit) on a Truck and How it Benefits Truckers

what is an apu on a truck

What is an APU on a truck?

An APU, or auxiliary power unit, is a vital truck accessory that serves as a power source and heating and cooling system for trucks. It provides an independent power supply to various truck components, ensuring smooth operation while the main engine is turned off. This technology enhances the driver’s comfort, reduces fuel consumption, and minimizes engine wear and tear. 

In this post, we will describe what is an APU on a truck, shedding light on its benefits and functionality. So let’s get started!

How does an auxiliary power unit (APU) work on a Truck?

The auxiliary power unit (APU) in trucks is a compact engine that provides various essential functions when the main engine is not running. It acts as a secondary power source, helping to reduce fuel consumption, emissions, and wear and tear on the main engine.

APUs typically run on diesel fuel and are designed to power the truck’s electrical systems, heating, air conditioning, and other onboard amenities. They are commonly used during rest periods or overnight stays, allowing drivers to enjoy a comfortable environment without idling the main engine.

When activated, the APU draws fuel from its tank and uses its internal combustion engine to generate electricity. This electricity is then used to power the truck’s auxiliary systems, such as heating and cooling units, electrical outlets, and even appliances like refrigerators or microwaves.

APUs are equipped with soundproofing technology to minimize noise pollution and often have automatic shutdown features to prevent unnecessary fuel consumption. Some advanced APUs also incorporate battery packs or solar panels to store energy for later use, further enhancing their efficiency.

Overall, APUs play a crucial role in maintaining driver comfort and reducing unnecessary fuel consumption, making them an indispensable component of modern trucking operations.

Different Types of APUs Available for Trucks

Regarding Auxiliary Power Units (APUs) for trucks, several types are available to suit different needs and preferences. Let’s take a closer look at three popular options: battery-powered APUs, diesel-powered APUs, and electric APUs.

1. Battery-powered APUs

These APUs rely on battery technology to provide power when the truck’s engine is turned off. They are designed to run quietly and efficiently, offering a reliable power source for various applications such as climate control, lighting, and small appliances. Battery-powered APUs are known for their environmental friendliness, as they produce zero emissions and contribute to reducing fuel consumption.

2. Diesel-powered APUs

These APUs utilize a small diesel engine to generate power. Diesel-powered APUs are known for their durability and ability to provide a consistent power supply for extended periods. They are particularly favored by long-haul truckers who require reliable power for heating, air conditioning, and other electrical needs during rest periods. However, it is worth noting that diesel-powered APUs do produce emissions and require regular maintenance.

3. Electric APUs for trucks

Electric APUs harness electricity from external sources, such as shore power or stationary generators, to provide power when the truck engine is switched off. They offer a convenient and cost-effective solution as they eliminate the need for an on-board generator or engine. Electric APUs are quiet, emission-free, and easily recharged whenever electricity is available.

Choosing the right APU for your truck depends on your specific requirements and priorities. Battery-powered APUs offer environmental benefits and quiet operation, while diesel-powered APUs provide long-lasting power output. Electric APUs offer convenience and cost savings by utilizing external power sources.

It’s important to evaluate factors such as fuel efficiency, maintenance requirements, noise levels, and environmental impact when deciding.

The Functions and Features of an APU on a Truck

An auxiliary power unit (APU) on a truck serves several important functions and offers various features that greatly benefit truck drivers. Let’s know what these features are:

  • Powering Electrical Devices
  • Heating and Cooling Capabilities
  • Reducing Noise Pollution
  • Fuel Efficiency
  • Environment Friendly

Why is an APU Necessary for Truckers?

An auxiliary power unit (APU) is an essential component for truckers, offering numerous benefits and cost savings. Let’s explore why truckers consider APUs necessary:

  • Fuel Efficiency: APUs are designed to provide power to various systems in the truck, such as air conditioning, heating, and electrical appliances, without relying on the main engine. With a dedicated power source, APUs reduce the workload on the engine and minimize fuel consumption. This improved fuel efficiency helps truckers save money on fuel costs and contribute to a cleaner environment.
  • Reduced Engine Idling Time: Truckers often need to keep their engines running while parked to power onboard systems or maintain a comfortable cabin temperature. However, prolonged engine idling is costly and harmful to the engine’s lifespan and the environment. With an APU, truckers can turn off their main engine and rely on the auxiliary unit to provide power, reducing unnecessary idling time significantly.
  • Cost Savings: By reducing fuel consumption and engine wear caused by excessive idling, APUs offer significant cost savings for truckers. The fuel saved by using an APU instead of idling the main engine can add up over time, resulting in substantial monetary benefits. Additionally, since APUs help extend the lifespan of the main engine by minimizing idling hours, truckers can save on costly engine repairs and maintenance.
  • Comfortable Resting Environment: Truckers spend considerable time on the road and rest in their trucks during breaks or overnight stays. APUs ensure a comfortable resting environment by providing heating or air conditioning power without relying on the vehicle’s main engine. This allows truckers to rest comfortably regardless of weather conditions, improving overall well-being and job satisfaction.
  • Noise Reduction: Engine noise can be disturbing, especially during rest periods or in residential areas where trucks are parked overnight. Truckers can significantly reduce noise pollution by using an APU instead of idling the main engine, promoting a quieter and more peaceful environment for themselves and those around them.

In summary, APUs are necessary for truckers due to their fuel efficiency, reduced engine idling time, cost savings, improved comfort, and noise reduction. Investing in an APU benefits truckers in the long run, both economically and environmentally.

Factors to Consider When Choosing an APU for Your Trucking Needs

When choosing an APU (Auxiliary Power Unit) for your trucking needs, there are a few important factors to remember. Let’s take a closer look at fuel efficiency ratings, compatibility with your truck’s electrical system, and cabin size/demand for power.

1. Fuel efficiency ratings

Fuel efficiency ratings play a crucial role in selecting the right APU. APUs are designed to provide power to your truck’s electrical systems and climate control without idling the engine, which can help you save on fuel costs. Different brands and models of APUs vary in fuel efficiency, so it’s important to look for units that offer optimal performance while consuming minimal fuel.

2. compatibility with your truck

Compatibility with your truck’s electrical system is another key factor to consider. Ensure that the APU you choose is compatible with the electrical setup of your truck. This includes considering factors such as voltage requirements and wiring compatibility. Choosing an APU that seamlessly integrates with your truck’s electrical system will ensure smooth operation and minimize potential issues.

3. Cabin Size and Power Demand

It’s essential to consider the cabin size and power demand when selecting an APU. If you have a larger cabin or higher power demands, you’ll need an APU to meet those requirements efficiently. It’s important to assess the power output capabilities of different APUs and compare them with your specific needs. This will ensure you have enough power to run all necessary equipment without limitations.

Frequently Asked Questions

Q1. How long can APU run on truck?

A. The duration that an Auxiliary Power Unit (APU) can run on a truck depends on various factors such as the APU’s fuel capacity, the load it is powering, and the unit’s efficiency. Generally, APUs are designed to provide power for extended periods, ranging from 8 to 10 hours or more. However, it’s important to note that individual APU models may have different specifications and fuel consumption rates. Hence, it’s always best to refer to the manufacturer’s guidelines for accurate information regarding a specific APU’s runtime.

Q2. Is the APU always running on trucks?

 A. No, the APU in trucks is not always running. It is usually activated when necessary, such as during idle periods or when additional power is required. However, once the truck’s main engine runs and supplies power, the APU can be turned off to save fuel.

Q3. Does APU turn off automatically in trucks?

A. The automatic shutdown feature in APUs is typically activated when certain conditions are met, such as when the truck’s engine is started or when the truck reaches a specific temperature threshold. This helps to conserve energy and prevent unnecessary idling of the APU.

However, it’s important to note that the specific functionality and settings of APUs may vary depending on the manufacturer and model of the truck.


Integrating an APU into commercial vehicles brings numerous benefits that improve efficiency and comfort during long hauls. From climate control to fuel conservation and access to electrical power, APUs provide drivers with a more pleasant and productive work environment. 

Furthermore, installing APUs showcases a commitment to sustainability and positions companies as responsible industry leaders. Therefore, it is evident that utilizing an APU is a smart investment for businesses seeking to optimize their long-haul operations.

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