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Do Semi Trucks Have Generators? (Explained and Solved!)

When the weather starts to switch to the extremes of hot or cold, it is good for anyone on the road to have access to an a/c or heater. 

Most cars rely on built-in climate controls, but semi truck drivers need to be a little more ingenuitive in meeting this need. 

Here’s a quick answer to whether Semi Trucks have Generators:

Typically, semi trucks do not have generators built into them. Instead, power is generated by the engine while it runs. However, when the truck is stopped for the driver to rest, having a generator or APU installed is a great way to power up auxiliary equipment in the cab while saving on fuel costs.

Do Semi Trucks have Generators?

Semi trucks can get very cold in the winter and very hot in the summer if it wasn’t for climate control (ac and heating). This is true for all automobiles though, right?

Well, yes. However, many state and federal regulations prevent semi trucks from idling on the side of roadways or elsewhere for environmental purposes.

This means a semi truck cannot generate energy with the engine while it is pulled over to power the heat. 

Generators are the best bet for ensuring truck drivers have a comfortable environment to rest and sleep in no matter the weather.

Some semi trucks have generators built into them known as APUs (auxiliary power units). These come at a cost, but they can be excellent for solving this issue. 

Some drivers opt to get a separate generator. These can be a little cheaper upfront but have some difficulties of their own. But, they are both better than freezing in the winter or burning up in the summer.

Do Semi Truck come with Generators Installed?

Not usually. Most semi trucks come with a heater and a/c, but these are powered by the diesel engine of the semi truck. A generator must be purchased or installed for most semi trucks. 

You can pay to install a generator, an auxiliary power unit, or purchase a separate generator. 

The unit you purchase depends upon your needs while on the road.

If you are commonly on long trips, an installed unit may be better. But, you may be able to get by with a small unit if you’re only on the road a day or so. 

What Would Semi Trucks Need a Generator for?

Generators are used for several reasons in semi trucks. One of the most obvious reasons is to power heat and a/c in the truck cabin. This ensures the driver has a comfortable environment to sleep, eat, and live in while on the road. 

Generators also power some modern conveniences such as coffee makers, microwaves, and a mini-fridge. Remember, you may be on the road a lot, and this can save you money in the long run. 

Last, it will save money over time since idling wastes gas (if you’re in a state which permits idling). Getting a generator helps to cut down on fuel expenses. 

Is a Generator better than Using the Truck’s Engine for Power?

Idling your semi truck engine is not recommended. Getting an APU or another generator is a better idea since it pulls the burden from the engine to the generator. 

Idling your truck causes wear and tear on the engine. This can cut into the lifespan of your semi truck and cause it to run less smoothly. 

It is also a waste of fuel. Even if your APU uses diesel to power itself, most APUs are over 90% fuel-efficient compared to your truck’s engine. 

How Much Does a Semi Truck Generator cost?

This depends upon what type of generator you choose to use, and whether you opt for an APU over a generator.

A gas generator can cost between $1,500.00-$3,000 on average. These have benefits. They are the cheapest option, they produce a good amount of energy, and they aren’t too loud.

However, since they are gasoline-powered, you’ll need to keep some containers of fuel on your truck to power it. 

Diesel powered generators are usually more convenient for most semi truck drivers. They use the fuel from the truck, and this cuts back on the need to think about whether you need to get a separate fuel to power it.

But they’re more expensive. They can easily cost $5,000-$6,500.

APUs are the most expensive option available. They can cost upwards of $10,000 new, if not more. They also need to be installed by a professional most of the time.

However, many truck drivers choose this option since it is one of the most efficient and produces the most energy. 

How Much does Installation Cost?

An APU costs more to install per unit than a generator. Most free-standing generators are relatively easy to use if you’re familiar with them, so it may not take much to figure out how to hook it up yourself. 

However, installing a generator can easily cost you a couple of hundred dollars. There’s no exact number estimate since it depends on your truck and generator, but electricians usually cost between $60 – $85 an hour.

Consider it can take a few hours to complete the connection and wiring. It can cost you $200-$250 to install. 

For APUs, the installation is more costly. APUs on average, cost $1,000-$3,000 to install since they require a lot more electrical work.

Most estimate that a complete cost for an APU unit, including installation, can be near $12,000-$13,000, which would leave the installation in thousands of dollars. 

How Much Fuel would be Saved over the Generator’s Lifetime?

While idling a semi truck can burn up to .6 gallons of fuel for each hour they idle. This number increases when the semi truck is loaded, and the heavier the load, the more fuel is burned. 

The costs of running a truck continuously can reach $1.00 or so an hour, whereas an APU or generator will cut the cost down to nearly $.20 per hour.

Some estimates have found that an APU or good generator can save up to 90% of the fuel that would otherwise be burned by idling. 

What Size Generator Would You Need for Your Semi Truck?

The size of your generator should be mainly based upon the number of appliances you think you will need to power.

If you are looking for the basics, such as an a/c unit and heater, you will be good with a 4,000 kW generator. 

However, you may want to consider finding a larger one if you think you will be on the road a lot. You may want to power coffee pots, microwaves, and other small appliances, which each require energy. 

The best way to ensure you will have a sufficiently powerful generator is to overestimate by 20% or so. Give it some wiggle room to help accommodate more applications. 

You can use this helpful calculator to help calculate the watts of energy your appliances require and what size generator is best.

Where are the Generator and Fuel kept in a Semi Truck?

Generators are typically on the back of the tractor portion of the semi truck. This is usually mounted to the frame, where it powers the semi truck’s electrical appliances. 

A handy video about installing your unit can be found here:

The whole video is helpful, but the portion directly about installing the unit starts around the 6-minute marker. 

The fuel must be in a secure container (not a milk jug or something) and kept away from explosive or flammable equipment.

Many truck drivers keep the fuel in the semi truck trailer because it should not be in the same room as people because of the fumes. 

Be careful it is not near any equipment which can be affected by the fuel or ignite it.

Is Having a Generator in a Semi Truck safe?

Generally, no you should not run your generator inside your semi truck. This is because they generate a lot of fumes and can make the air toxic to breathe. 

Your best bet is to keep your generator outside while running or have it installed behind the cab, as described previously. 

Some truck drivers store their units inside their cabin when it is not running, but even this can be dangerous if there’s any lingering fuel in the machine. Gasoline is a hazardous fume, and you may wish to store it in your trailer. 

Is the Sound of the Generator Troublesome?

If you’re far out in the middle of nowhere, then the noise may not be the utmost concern on your mind.

But, semi truck generators have to operate at truck stops and other public areas. In these instances, the noise can be bothersome. 

In comparison to most gas generators, APUs have better sound control. Especially the environmental unit, these produce far fewer decibels of sound per minute, with many registering below 80. 

However, there are more noise friendly generators as well, which may suit your needs. Just be careful about the unit’s specifications and make sure it will produce the power you need. 

Is it a Fire Hazard?

Essentially, any time you are using a fuel-powered generator, the storage of the fuel should be the utmost consideration. Many states have an 8-gallon limit rule for keeping your fuel. 

Anything above that may be considered transporting hazardous materials which could require special permission to do so. 

You should be careful to have the area well ventilated, store your unit away from flammable objects, and have it outside while it is running. 

What about the Fumes?

Fumes from generators are a serious concern. Never run your gas generator inside your truck cabin.

Also, when running it outside, try to have it run away from windows and doors where it can leech the fumes into the cabin. 

You want to adhere to similar rules when running a generator on your truck as you would for your home regarding fire hazards and fumes.

To help monitor this and prevent a build-up of fumes in your cabin, you may want to invest in a carbon monoxide detector. 

It is better to be cautious to avoid poisoning. 

How is the Generator in a Semi Truck Connected?

Although the exact specifications vary a little based upon the unit, they are usually mounted in the back of the tractor and connected to the battery. 

Most units will come with a control panel of sorts which you can use to regulate the use of the generator. Most mount this on the back of the cab near where the unit is installed to make it simpler. 

Make sure the unit is securely fastened to the railing in the back of the tractor. You will likely want to use screws and clamps to help secure it.