How to Keep Your Generator Running in Silence

Gas and diesel generators have a shared and massive flaw. They are extremely loud.

When times are good, and you’re using it during a temporary power disruption, this is only an annoyance. When we find ourselves in a SHTF situation, a loud generator signals to everyone around us that we’re an excellent target for looting.

The best option is to use a solar power system, but these have a high initial cost to get set up, which leaves many preppers relying on generators for emergency power until they can afford to upgrade to solar.

I have a 3000-watt generator, which was my first emergency power option before I upgraded to a solar-powered battery bank. For those of us who have generators, it is a good idea to have ways to silence or suppress the noise they make when we need them in a SHTF situation.

First Steps

The best way to silence a generator is to buy the quietest generator you can. Inverter generators are often the much quieter option, and if you’re looking to buy a generator, you should consider the rated decibels in your decision.

The problem with inverter generators is that they are also more expensive, so you may need to settle for a cheaper and louder generator.

Water Muffler

You can use a flexible exhaust pipe in which you place the open end into a bucket of water. This helps to reduce the noise that is caused by the exhaust pipe.

If you do this, the generator must be higher than the water to avoid the generator sucking water back up through the pipe and into the engine.

Location, Location, Location

Where you place the generator is a significant factor in how much noise you and those around you will be subjected to.

Ideally, you want the generator to be as far from the house as possible and in a location with enough objects around the generator to block the sound waves from travelling too far. If you put it right up against the wall of your home, the wall will amplify the noise in one direction, which is not what you want.

Placing the generator on a soft surface is also a great way to absorb some of the noise that is created.

In a perfect world, you would build a dedicated shed for the generator, which is totally soundproof. Building a shed like this has complications around routing the exhaust to the outside and providing enough clean air to the inside.

For most of us, building a simple baffle box is the most cost-effective option for silencing a generator.

Building a DIY Baffle Box

A baffle box is a small enclosure that fits over your generator and is lined with soundproof materials. The exhaust is routed outside, and clean air can flow in. The advantage of these boxes is that you can place the generator in a good position and then place the box over the generator to deaden the noise.

Expectation vs Reality

A baffle box will not eliminate all the noise, but it will reduce the decibel level to a point where the sound is manageable. The box I am going to detail here is the most cost-effective box that you could construct, but I will also give you some additional options that you can consider, but they will come with added costs.

Materials

You’ll need only a few materials easily found at the local hardware store for a basic baffle box. You’ll need to source more specialized items if you want an improved version.

For this build, you’ll need:

MDF Boards
Soundproofing wall boards
Nails
Glue
Flexible exhaust pipe

Instructions

1. Start by measuring your generator.

2. Once you have the overall outside dimensions, add the thickness of the sound proofing and a few inches all around to get your inside dimensions to which you’ll cut the MDF boards. It is easiest to sketch everything out on paper to ensure you make no mistakes.

3. Cut the MDF boards to size. Assemble the boards to make a box with an open bottom.

5. Cut or drill ventilation holes at the top and bottom on the opposite side of the baffle box.

6. Make a cutout to fit the flexible exhaust hose. You’ll need to consider that the hose will get hot, and you may need to add some fireproof insulation around the pipe to prevent any issues with the hot pipe touching the MDF.

Depending on how you want to place the box on the generator, you may need to cut a slot to fit over the exhaust hose instead of only a hole.

7. Notch an area at the bottom to allow extension cords to be run under the side of the box.

8. Line the inside with soundproofing.

9. Attach the exhaust hose.

10. Start the generator and place the box overtop.

Testing

The decibel level of my generator was around 78 decibels. With the baffle box installed, the decibel rating fell between 68 and 72.

The difference was enough that if you were to stand on the street in front of my home, you would not be able to hear the generator in my backyard.

Improvements to the Baffle Box

If you want to improve on this design, there are many ways that you can accomplish this. The first is to use multiple layers. You can use rigid foam with a layer of expanding spray foam in between.

A better option is to use materials designed specifically for soundproofing.

The inside of the MDF box should be covered with Mass-loaded vinyl (MLV), a flexible sheeting that blocks sound waves from getting through. On top of that would be acoustic panels, and all the seams would be sealed with acoustic sealant.

This option is the best but will also increase your baffle box’s cost from less than a hundred dollars to several hundred dollars.

You could also include doors to access the pull start, fuel tank, and control panel.

If you’re planning on relying on a fuel-driven generator for your grid-down power needs, then it may be a worthwhile investment.

However, suppose you’re like me and only have a generator for short-term backup power during short-term outages. In that case, a simple baffle box may be all that’s required.

The best option for backup power is solar-charged battery banks. Since this option is often costly, most preppers usually start with a gas generator.

If this option is the one you’re taking, finding a way to keep your generator as quiet as possible will be essential. To this end, a combination of the quietest generator you can buy and a baffle box will be the best bet to keep your portable power a secret.

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