Generator noise

BlueGekko · 07-22-2021, 07:47 PM

We have a 2019 Navion 24D and are generally pretty happy with it. It’s equipped with an Onan QD3200 quietdiesel generator. My research found that it generates 68 decibels when used. In a quiet campground (Forest Service or Nat’l parks) or one in which the neighbors are pretty close, 68 db sounds embarrassingly loud so we don’t use it very much. Is there a way to decrease the db level of the diesel genset? A search on classbforum.com found a product called Roadkill by Stinger. The review sounds convincing but . . . roadkill by Stinger? Sounds a lot like a prank. Anyone used this material or have other sound deadening ideas?

jhedges · 07-23-2021, 02:47 AM

Almost all campgrounds I've been to ban the use of generators while in the campground.

BlueGekko · 07-23-2021, 05:18 AM

We’ve been on a road trip out west for three months. If a campground has electric hook ups, it’ll ban generators. Otherwise, they can run during specific hours. In our experience most state, federal and forest service CGs have specific hours, usually until 8:00 pm.

Marine359 · 07-23-2021, 05:42 AM

I wouldn’t worry about 64db. It’s about average.
Recently at a NP with generator hours 8am to 8pm. Fortunately most campers would rather hear birds singing in the morning than generators purring. So, it’s really unnecessary to fire it up until 10am or later. Unless it gets really hot before then, there’s no need to run A/C.

backtrack15 · 07-23-2021, 06:30 AM

I don't love generators; but they're at least something you can "tune out" because the sound is fairly uniform (and I certainly understand why people need to run them for a bit). I do wish they'd stop installing exterior speakers on trailers, as music is much harder to ignore.

BlueGekko · 07-23-2021, 07:11 AM

The issue isn’t whether CGs allow generators. My question is how to make mine quieter.

Morich · 07-23-2021, 07:30 AM

Each generator will have different layout on mounting so some study of what you have will be needed but I've just gone through building a "shed" for a portable here at home and there are some common ideas that can be used when dealing with sound.
Step one of course is to not make as much to start but that's not an option with a noisy one like you have.
Step two is learning how sound travels and that leads to what you can do next.
What I found was deflect first as the sound waves tend to move in straight lines that can hit slanted walls to deflect them down or away from where you want quiet. Deflecting it down so that it hit soft dirt is good!
But then you will also want something to "soften" or break up what is still a problem, so layers of differing materials is a good next step. I found panels made of cardboard, forming a "sandwich" of other layers of a fabric packing material and then foam insulation board cut my noise way down.

Doing this on a built-in generator is going to be much harder due to limits on space but playing with the different methods may get you closer to what you want. Simply wrapping the genset in any material is not going to work due to the heating factors. Directing the exhaust up will get some but much of the noise comes directly from the generator body.

One handy tool to use is to download a sound meter for your phone as it gives a much more definite answer than our ears which are pretty unreliable.

One first thought might be to look at hanging something heavy like packing blankets, stapled to something firm like cardboard at an angle to slant the sound down to the ground. At least this might be done on the outer edges, where the noise is most prone to be a problem.

Not an easy problem to solve but it can be made better.

For details on what worked for my specific want/needs, this is the posting but it got way too muddy at the start so you might want to skip down to post 29 to get into anything usable!

https://www.winnieowners.com/forums/...-360441-2.html

bigb · 07-23-2021, 10:50 AM

I like your portable generator sound deadening project but like the OP, I too have an on board QD3200 and also find the noise level embarrassing, The exhaust is not too loud except when the AC first starts but the diesel unit has a low pitched throbbing that carries a long ways. I am going to try the water bucket idea but I also wonder if that would create too much back pressure?
We only use the generator when driving to keep the rear of the coach cool or when parked at a restaurant etc because of the noise level. I am considering removing it altogether and replacing with a portable Honda EU 2200i and propane kit. The Honda weighs around 60 lbs so I'd be dropping 140 lbs and the Honda could store right there in the generator compartment. I'd throw a soft start kit on the AC which is only a 13.5 and I think it would work fine. I could even rig an exhaust system and leave the Honda locked in the compartment with cooling provided from underneath like the QD uses now.
It seems like a win-win since I'd gain precious payload capacity which I am extremely short on (can't even take our bikes) and solve the generator noise and stink.

hank857 · 07-23-2021, 10:56 AM

Mil generators are the noisiest and they have ways to quiet them down a bit. These gens were/were open frame like contractor gens. They used metal flex pipe over the exhaust and ran it about 6 ft away from the gen. It terminated in a hole or under some sand bags to muffle the sound. Now cg will not let ya dig a hole so you would need to find an alternative. Also some would put the gen in a hole about 3 ft deep to help keep noise down. BTW normal conversation is about 65dbm so that gives ya an idea of what you are dealing with.

crah · 07-23-2021, 11:44 AM

I've had numerous RVs and generators and the Onan quiet diesel 3200 is by far the loudest and most embarrassing. Original poster, I'm with you on how loud it is. Some people don't care and think its fine. I'm looking at using some sound insulation board that is made for outdoors. Many people think that the view/navion generator is built in. That is not the case. Technically it's mounted open under the frame. It looks like it's built in because you have to open a compartment door to get to it but that compartment door is just for looks. All the noise on the 3200 diesel is coming from the engine itself. I've tried exhaust mods and they have 0 effect. I would use sounds panels that absorb the sound. Keep us posted on what works for you. It's on my future mods but I have many in front of this one.

Elkman · 07-23-2021, 11:48 AM

No way to make the generator quieter. Best approach is to minimize its use. I added additional solar panels and replaced the lead acid batteries with lithium-phosphate ones and this cut my generator usage by half. The lithium-phosphate batteries can go twice as long to operate the electric only fridge and freezer and these batteries recharge 3 times as fast from the solar panels and or the generator.

With my prior RV I did not even have a generator and if I needed to run the AC I would stay at a place with shorepower. While on shorepower I would conserve propane by using the microwave instead of the propane cooktop for meals and the 3-way fridge was not consuming any propane.

In general the places with shorepower are a lot quieter overall as too many people are very inconsiderate about running their generator day and night. It is risky after the curfew for generators to knock on the door of the RV and take a chance of getting shot by its paranoid owner.

bigb · 07-23-2021, 11:51 AM

BlueGekko I have used sound deadening in my rig to stop vibration and rattles in the dash just not the Roadkill brand. It worked well for those vibrations and rattles and may help some with the way your generator is mounted if you can fit some around it. Mine is mounted inside a compartment with sound deadening and I have no other places to add more, and it is still too loud for us. You also have to be careful not to block cooling as the QD3200 has barely adequate cooling to begin with and can overheat in desert temperatures. In view (no pun intended) of how yours is mounted per the previous poster crah it sounds like there is room to add it and in your case it might be worth a try, if you decide to try it keep us posted.

Morich · 07-23-2021, 02:56 PM

Once I got the meter to get some actual readings, I got a totally different idea on sounds and the test measurements.
When ads say the level of a conversation is above 60 DB, I know they are speaking from experience with going to too many concerts and they are half deaf!
We find 65 DB to be way more than we want in the area while we are trying to talk, so did not even start with that idea.

We also find the exhaust is not a major factor when it comes to quiet but is a good thing to manage as far as heating the genset and moving the fumes up and away. If I were wanting to quiet a built- in set, I would look at panels to prop or attach on the sides and then more to enclose the underbody if possible. Possibly something squeezed up tight against the RV body? Then, since this will cut off air flow, I found using a junk fan out of an old microwave to be a good way to move air in a vent, across the engine and out the other side. They move a good amount of air and since they use 110 AC, they could be wired to plug into the genset.

BlueGekko · 07-23-2021, 08:29 PM

I found a product online - Dynamat - that seems like it’ll work to reduce some of the noise. Several RVer reviewers have used it to reduce noise from the dog house and genny. Will order and try it when we finish our road trip in August. If my random access memory is still working then, I’ll post positive results. We have enough negativity in life that I won’t post negative results.

bigb · 07-24-2021, 07:07 AM

Quote:

Originally Posted by BlueGekko

I found a product online - Dynamat - that seems like it’ll work to reduce some of the noise. Several RVer reviewers have used it to reduce noise from the dog house and genny. Will order and try it when we finish our road trip in August. If my random access memory is still working then, I’ll post positive results. We have enough negativity in life that I won’t post negative results.

Dynamat is the holy grail of sound deadening mat and the price reflects that. There are many copy cat brands for much less $$$, myself I used Noico which worked just as well. These products do not have the padded insulation that your initial product has. Dynamat and others are simply a heavy foil with a heavy, adhesive asphalt looking layer on the back that sticks to panels and stops them from vibrating and rattling and may reduce some noise transfer.