Small Generator Enclosures to Limit Noise?

kaipo_boy

Still learning... but my tiny (208 AH) 24v battery bank appears to run down to near 70% SOC by morning if it begins the evening with a nearly full charge that day (i.e., it has hit Float or is at or near the tail end of its Absorb cycle). But I have run into an unseasonal amount of cloudy weather, and for several days now I have run just a little bit of charging time into the batteries in the early morning (6am ish) to bump them up before the sun comes up, as they indicated near 50% SOC. Since the nature of PV seems to be only a trickle in the early morning, this setup seems particularly well suited to a short time on the generator in early morning before the sun gets serious, then let the PV finish up, even cloudy days will finish them if you give them a short shot in the morning on the genny.

I live in a pretty well populated area and don't wish to tick off neighbors that early in the morning; even though my Ryobi 2200w 'suitcase' type genny is pretty quiet (perhaps a tad louder than a Honda EU2000i), it seems pretty easy to build a small enclosure to make it quieter still... does anyone have a link to someone who has posted plans or pics to a quieting enclosure/sound absorbent materials to use? My Ryobi is maybe 45 lbs; I am not thinking of something the size of a shed... perhaps more along the lines of a doghouse sized enclosure.

BB.

This guy did pretty well with cheap components:

https://www.youtube.com/watch?v=XX2xvGYn5ao
https://www.youtube.com/watch?v=LnHpkgjVfk0

I am not sure the covering (Styrofoam?) on the outside does any good... And watch for engine temperatures and recirculating exhaust fumes back inside (carburetor/cooling recirculating "bad" air)...

I would probably look at a baffle in the middle of the box that fit down over the genset (roughly) that would keep cool/fresh air at the intakes and hot/exhaust air at the generator vents.

-Bill

Graham Parkinson

Hi - Having lived with generators for years in mining exploration camps I know what you mean. Sound dampening enclosures are a difficult balance between enough air supply for combustion, engine cooling and airtightness for containment of sound.

Even a small opening with a direct path will transmit a surprising amount of sound. Best strategies are something dense and non-rigid as attenuating media, ie sand infill between double walls ( walls of preserved studs and preserved plywood, Hardi board, cement board etc.) Don't couple inner wall to outer wall (ie use staggered 2x3 studs so each wall is independently supported. Could alternately use cement blocks walls, infill with sand.

I've seen exhaust pipes routed through buried drums. Air supply via foam lined large diameter ducts with bends to prevent sound radiation or acoustic foam lined baffles. Probably will need positive ventilation (electric blower into enclosure).

Best acoustic foam is the type sold for boat engine rooms - synthetic foam sandwich with thin lead layer in centre to create both outer layers of absorbing/isolating media and central heavy dense medium (lead) for preventing transmission by reflection. Expensive stuff though. Fiberglass insulation isn't as good as you might think it would be for engine type noise but better than nothing.

On one of my enclosures I made the entire doghouse sized cover hinged so that you could flip the whole thing off to check oil, etc.

- Good luck, be safe => provide adequate cooling so generator doesn't get cooked like one of mine did ...... Graham

Vic

Commercial Sound Attenuating genset enclosures routinely use Polyurethane foam on the interior walls. It is flammable and can emit toxic fumes when burned, but believe that the foam on enclosure walls probably use a flame-retardant of some kind.

There is also a fibered cellulose looking board that helps dampen vibration in walls. Have also seem sound-attenuating gypsum board, but these products will still need to have structural members decoupled from the inside wall to the outside wall, to be most effective, as was referred to by Graham.

FWIW, Vic

westbranch

Search out a user here, ChrisOlson he wrote about his small enclosure and it was very quiet

oil pan 4

The small diesel inverter generators I work on have fiberglass insulation for sound deadening. I need to get a picture of one of these little rigs some time, they are pretty cool.
They also use small 12volt, 1200cfm fans prevent air circulation for fast warm up and extended heat retention after shut off. Then use a temperature switch to turn on when the generator needs cooling.

Brlux

I was working on an off sight movie set and they would drape their EU2000 in several layers of moving blanket so that there was an opening on each end. I think there was a warning in the manual about not doing this but it sure was effective.

mike95490

Build a 6' high "fence" from dry stack concrete block, leave the roof open Noise bounces around inside, eventually goes up and not so much horizontal. Leave plenty of space for cooling air.

Still too much noise, go higher till it's OK. use a baffled entry way with sound absorbing panels to allow entry for oil changes and fuel.