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How Does a Semi-Truck APU Work?

How Does a Semi-Truck APU Work?

Semi-trucks and other heavy vehicles are equipped with various small electric appliances for multiple purposes like AC for cooling and heaters to control temperature in winter. They use engines to power these accessories which requires a lot of fuel. So APU and other alternatives are in demand to power these accessories.

How Does a Semi-Truck APU Work? APU is a small generator that can power the electric appliances in the semi-truck. They either have diesel engines or batteries to produce energy. It is fuel efficient and environment friendly and helps comply with idling rules.

These devices are becoming famous because all environment-regulating companies aim to reduce energy consumption and save fuel for a better environment.

What is APU in a semi-truck, and its different types?

APU is also called an auxiliary power unit and is installed in 18-wheelers like semi-trucks to power small appliances like AC heaters or lights. It is just like a small generator that is used to power the accessories of the vehicle.

It is a small, heavy-duty motor that turns on all the electric appliances without turning on the truck’s engine. It is available in different sizes and models, all with various features. The choice of a suitable APU depends upon the truck’s size and the electric appliances in the semi-trailer.

It has two types depending upon its technology. One is combustion or diesel APU, and the other is electric APU.

How does APU work in semi-trucks?

The working principle of the auxiliary power unit depends upon its type. A diesel APU is mounted on the sides of the semi-truck.

It has a small diesel engine that uses fuel to deliver power to the APU or a small generator. When it is turned on, it cuts off the fuel supply of the truck engine to save fuel.

Electric APU uses batteries to power the small appliances in the vehicles. Usually, a 12-volt battery is integrated into the battery system of the truck. It does not use the power of the semi-truck battery.

What are the benefits of APU in semi trucks?

These auxiliary power units have a lot of benefits for the heavy trucks. Here is a brief description of all of them.

Better fuel economy

The heavy trucks are used to haul heavy loads to far-off places. The drivers usually take short breaks on their way to their destination. They take naps by turning on the AC or heating system in the winter.

Operating the AC or heating system in the semi-truck cab burns a lot of engine fuel. The cost of fuel spent to run these appliances, even for one or two hours, is very high. But APU can be a lifesaver in this situation.

It is a small generator that can run these electric appliances with much less fuel. A semi-truck without APU burns about 70% more fuel in operating the AC in summer.

In the same way, turning on heaters in winter can burn 80% more engine fuel without APU. Installing this small generator can save fuel costs to trucking companies.

Environment friendly

Trucks and other automobiles are a big reason for air pollution in big cities. The trucks, when idle, also continue to release toxic gases due to the burning of fuel.

According to statistics, idling vehicles without auxiliary power units produces millions of tons of carbon monoxide, nitrogen oxide, and other harmful chemicals in the environment. In such conditions, APU can save the cities from this problem.

Vehicles having this equipment to power small appliances have a lesser contribution to producing air pollution. They can help improve the air quality in big cities and prevent other health issues for the residents of these areas.

Idling regulation compliance

During idling, the engine is running while the vehicle is not moving. Idling regulatory rules are established by the government and concerned authorities to minimize air pollution and control fuel wastage.

These rules are made to ensure the security of the fuel and to protect the air from getting polluted. According to these rules, any diesel or gas-powered vehicle should not stand idle for more than a few minutes.

The semi-truck drivers are used to idling vehicles during their long journeys. It can get them into great trouble due to vehicle idling rules. Having APU can save them from fines and other punishments due to violation of laws.

It allows the driver to idle the vehicle without turning on the engine. It ensures better compliance with all the idling rules and permits the fatigued driver to take a rest.

Reduces truck damage

Idling a semi-truck for a long time can damage its engine parts and other components. It spends up the wear and tear in the engine parts due to an incomplete combustion cycle. The drivers have to spend a lot of money on repairing and replacing the damaged or broken parts of the engine.

APU shares the burden of the engine and reduces the normal wear and tear in its components. Turning on the auxiliary power unit will cut off the power supply from the engine.

It also allows it to cool down when the vehicle is not moving. This way, it can save a lot of money for the drivers as they do not have to repair the vehicle often.

Is APU a cost-effective option for semi-trucks?

There is no doubt that these generators save us fuel costs, but there is another picture of the story. They are a lot more expensive to buy for an ordinary truck driver.

On average, the cost of APU ranges from $13000 to $14000.Its installation cost is also high and depends upon the professional. This much money is not easy to save to get these auxiliary units to save fuel costs.

These equipment also require maintenance at regular intervals to make them last long. On average, it is expected to cost about $7000 for their maintenance. So, higher purchasing and maintenance cost is the main downside of these units.

How long does APU last in semi-trucks?

Like all other equipment and machines, these auxiliary power units also wear out after some time. On average, the APU comes with a 2 to 3 years warranty, and it can last for more than 2000 hours with proper maintenance.

Some higher-quality brands can offer higher warranties for their products. This equipment needs maintenance every 6 months to increase its lifespan.

Diesel or electric APU: which one is better?

Both types have their own merits and demerits, and the selection of a suitable APU depends upon personal preferences.

As far as the diesel APU is concerned, it is powered by a small diesel engine, and it can deliver an uninterrupted energy supply to the electric appliances in a semi-truck. It is suitable for drivers who travel frequently to areas with extreme weather.

It can run the AC or heaters for more than 10 hours. But it requires more care and maintenance. You have to change the oil and belt frequently to maintain its functioning.

In electric APUs, rechargeable batteries are used to power the small appliances. It is suitable for those who spend less time on roads and travel short distances. These types of units require recharging after a few hours and can supply energy for only a few hours.

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