Quieting generator for neighbors? 1

[LMF5000]

Because of the way the world is going, I just bought a portable generator for emergency power. It's a Chinese clone of the Honda eu2000i . I measured about 70dBa from two car lengths away.

I will be running this to power my ground-floor apartment but I'm concerned about the annoyance it will cause the neighbors. Running it in the backyard the noise is very obvious and I'm sure it travels up to where all the neighbors are (there's 5 floors of apartments above mine).

I have a small brick outhouse in the yard (small meaning 1m wide, 1.8m long and 2m high - about the floor area of three washing machines). I've considered locking the generator in there and plumbing the exhaust outside, but I'm concerned that it will overheat since there's no ventilation and the walls are 20cm concrete block. The door is aluminium with glass panes, about 90cm wide and 1.9m high. Is this room too small to passively handle the heat from a 2kW generator?

Another option I considered is a quiet box. I previously built one for my dad's generator (a 4kw open-frame non inverter). We used plywood lined with foam and put two intake and two exhaust baffles, plus a centrifugal blower for forced ventilation. It reduced the noise of that generator from 77dBA to about 67dBA, but the box is massive and weighs about as much as the generator (30kg). Is there some way to construct a quiet box that's also lightweight and cheap? The generator cost €500 so I'd rather not spend $1200 on a professional quiet box.

Last option I've considered is running it in my garage that forms part of the underlying garage complex, but then it would be running relatively unattended, and the fumes and noise would be getting dumped into the common parts of the garage complex which might cause more problems.

Thoughts?

 

[LittleInch]

See this thread.

https://www.eng-tips.com/viewthread.cfm?qid=486613

And go all the way down to the final post from the OP who is in a very similar situation. His recommendation? Buy an off the shelf solution....

Also do a search in the top right on generator noise. Lots of people have had the same question over the years.

Gen sets like that are designed to work in the open air. Enclosing them is problematic for any long term operation in terms of air supply for the engine itself plus cooling loads.

Don't put it in the garage. You could easily cause problems for other people and could create a hazardous atmosphere, never mind the noise.

Light cheap and simple. You might get two of of three.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[wayne440]

You may find that the sound of any generator, no matter how well muffled, will "generate" complaints from neighbors who don't have one of their own. IMHO, 70dBa is quiet enough to be reasonable, normal conversation is 60-70dBa.

I have developed a method that you may find useful- do not take ownership of the issue. When you get a complaint, point out that the primary cause of discomfort is not your generator, but rather the fact that the utility has failed - and that when the utility power is restored, you will shut the generator down promptly. Then offer to provide a phone number for the local utility.

 

[LMF5000]

Littleinch - thanks for the link. Calculating temperature rise with a known forced flow rate looks to be simpler than I thought, but conduction through brick still eludes me. Anyway key takeaway is that as I suspected, things won't go well if I run it in the outhouse. Well, unless I find a way of cooling it.

Wayne - I actually pondered offering them free electricity via extension cord for the duration of the power cut. That turns it from "annoyance" to "lifesaver" real quick. The problem is that there's 5 apartments above me, and 15 apartments within earshot. I sized the generator perfectly for my needs. I wanted it small and light, and this one is around 25kg so I can move it around one-handed. It outputs 2200W peak, 1800W continuous. I mainly bought it to run my microwave (1300W actual consumption), air fryer (1600W), washing machine (300W), fridge (1000W starting, 170W running) or dryer (570-1100W). So if the neighbors join in it will run their electronics, but throw in more than one fridge and the starting surge will most likely trip the overload protection. And non-engineer neighbors can't be trusted not to try running a 2000W toaster or 3000W tea kettle once they get the extension cable to their home. Plus I'd probably be liable if their appliances are damaged by the power. So I abandoned that idea.

Easiest solution is to hide it under an awning and hope nobody realises the noise is coming from me . But since petrol goes bad I still have to run it once a month to keep the carb clean and boil the condensation out of the oil, so I can't always blame it on power cuts.

 

[wayne440]

I do not store my small gasoline(petrol) fueled equipment with fuel in them. I run the tank dry, put them in storage and do not worry about condensation in the lube oil. Pour in fresh fuel and they are generally ready to go. This afternoon, I started a small mower that had been stored in that fashion about 7 months ago, no issues at all.

I do not recommend running a cord to any of the neighbors. But if a friend wants to stop by and put something in the microwave, that is a bit different.

 

[LittleInch]

I'm not sure you've thought this through.

How long do you plan to run this generator and for how many days?

Fridge and freezers will be OK for a few hours if you keep them closed but then need to run for probably 30% of the day in periods of one to two hours. Can't see in an emergency why you would want to do any washing but a washing machine eats power die to heating the water.

How much fuel storage do you have? These generators eat fuel but have a small tank so you end up filling them every 2 hours.

No lights?

How do you plan to connect the power? Plug each thing in one at a time to an extension lead?

But the noise will not go down well, especially if everyone has lost power for hours or days.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LMF5000]

I'm in Malta (Europe) so things are a little different. Power cuts (for now) tend to last about 2 hours. The longest we had was 12 hours when the 40-year old connection between the house and the overhead power lines failed and we had to wait for the utility company to have workers available to fix it. Effectively the generator will be there for convenience and as a backup to my battery and inverter setup. I've never managed to run a generator long enough to run it out of fuel, even though I only put a few liters in at a time. I keep a small amount of petrol stored in a 10-liter jerry can and then there's whatever is left in the generator's internal 5-liter tank.

I'm in the middle of a test at the moment. I waited for the low fuel light to illuminate in my car, and dumped the old fuel from the jerry can into my car (it was about half full, so about 5 liters). Basically part of the process of rotating out old fuel from storage and replacing it with fresh. So far the tripmeter is showing almost 2 hours of driving over the last four days and the low fuel light still isn't on. But it's impressive that such a small quantity of petrol can run a 1400cc turbocharged car engine for that long. The generator is 150cc, and I think the specs say 10 hours of running on a full tank at half-load. This being an inverter generator it runs lower-power loads at much-reduced rpm.

I plan to connect it by suicide cord (backfeeding through an outlet). The utility meter has a disconnect switch built in which I toggle and I also have another 5 protective switches (RCBs etc.) which I switch off between the utility supply and the house circuits. Essentially the house gets isolated off the grid and I use the existing wiring to distribute the electricity to every room. Since each outlet is rated for 13A at 240V (UK system) it's more than capable of handling my 2000W generator or my 500W inverter. But really the critical things are lights and modem, which consume some 50-100W and the inverter is more than capable to handle. The fridge/freezer are rated to go 17 hours between power cuts according to the manual (and we store water bottles in the fridge to increase thermal capacity) so it's unlikely I'd need to run them on generator.

I mentioned the washer and dryer because that's far more likely to qualify as an "emergency" needing a generator. Picture needing to dry a wet uniform asap, that sort of thing.

 

[Palletjack]

1800 watts continuous and you plan to run all those things off that generator??
I see you have your watts calculated and usage will have to be cycled between appliances.
I guarantee if you invite neighbors to plug in there will be no cycling of appliances and arguments will follow. The generator will not handle all that loading.

 

[LittleInch]

You can't run the generator and the battery powered invertor at the same time mind as they won't be synchronised.

The 5 RCBs will be running off the same board so you really only have one breaker between you and the grid. Get this wrong once and your generator will be toast.

But the original question still remains- noise.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LMF5000]

Yes, I will cycle appliances (only one on at any one time). And yes I'd be running either inverter or generator, never both at the same time. And the minimal headroom is why I quickly abandoned the idea of trusting the neighbors to operate only one low-wattage appliance if I offered them free electricity

 

[LittleInch]

I would get a bigger battery and just use that for your electronics. Then charge it if needed from the generator.

Or try this?

https://aquietrefuge.com/build-soundproof-box-for-generator/

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[itsmoked]

In your particular situation I'd suggest you leave the fuel generator as a last resort. Instead, build yourself one of these(see below). Then there's no noise whatsoever and little to do when the lights go out. You also cut short the VERY typical cycle of getting out the gasoline lunch-pail, running extension cords everywhere, and getting all set up. You start the generator, get back upstairs and..... the utility power returns.

With something like this the power goes out, you run a few cords to what you need to run and you're in business. You also plug this thing in and when power comes back nothing at all happens except this unit starts re-charging. You can continue to do nothing as in stormy weather the power could go out again or blink a couple of times. You can't do this with a generator as the neighbors can legitimately complain.

Nothing you have still running on this would notice or be interrupted during subsequent utility upsets. When the likelihood of further interruption has dropped to zero, at your leisure, you can switch stuff back to your utility outlets.

If you have a prolonged outage you run on this as described above and before evening you proceed with the hassle of using the generator to run the line-input on this unit to fully recharge the battery then dump the generator and put it away at dusk. Then you have many hours of husbanded silent power to run with. You leave it plugged into an outlet so whenever the utility comes back it starts recharging again.

DIY LiFePO4 Version of the EB240 Solar Generator

Keith Cress
kcress -

http://www.flaminsystems.com

 

[stevenal]

Negative on the suicide cord. Do it safely and correctly, or don't do it. If you're really an engineer, safety should be paramount.

Cooling is not the only issue with an enclosure, you need air for combustion.

 

[EdStainless]

I have a neighbor that used a small box as a transfer switch.
It contains a duplex outlet, a breaker, and the connection from the generator.
Yes, he has to run extension cords.
But it doesn't need professional installation and it works for a small generator where you will only be running one thing at a time anyway.
I have seen commercial ones in the US for about $200.
They are often marketed as being for a heating furnace.
These are meant to be hard wired but there is an access plate that you can remove to mount the outlet.

On the noise side, how much will this run at night? That is when it is likely to be an issue.
You could use your outhouse and add a forced ventilation fan to bring in outside air.

My daughter lived in an apartment where one tenant had a generator.
During outages he would put a small table and couple of chairs out in the hallway along with a strip that had 4 2A USB connections.
This way neighbors could keep phones and such charged.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[wayne440]

Good idea. During the last significant outage here, one of my neighbors asked to borrow a generator. I told him I would loan it, but getting diesel fuel would be his issue. The reply was "Just diesel fuel? We have about 400 gallons in our farm tank, come get all you want...". I delivered a 10kW generator, the first question was "can I charge my cell phone now?" If you provide a way to charge phones, your neighbors may not care how loud the set is.

 

[bacon4life]

Get a generator intended for use in a populated area. The generator seems to be a very poor clone, since the actual the Honda EU2200I is rated at 57 dBA.

The noise ordinance in my county has limits at the property line between residences of 55 dBA during the day and 45 dBA at night.

Do not use a double-ended suicide cord. Unfortunately, that name is not full descriptive of all the folks that a double-ended cord can kill. In addition to killing yourself with it, you could kill:
1) utility workers attempting to repair the power lines
2) your neighbors if your generator backfeeds a downed power line
3) anyone standing by your generator when utility power is restored, since your generator may explode
4) your friends/family if they incorrectly attempt to use the cord

 

[LMF5000]

I actually did build a battery-operated inverter unit like the one Will did in the linked video - but since I'm in Malta, LiFePO4 batteries are immensely difficult to source unless you can afford to pay 2x their cost in shipping. After 6 months searching I gave up and built mine with a deep-cycle 32Ah 12V AGM lead-acid battery. It's not even close, I've had it for two years and the battery has already lost 12% of its capacity after some 20 deep cycles (from 25Ah real-world capacity driving a 100W load down to 22Ah under the same conditions).

Here's my generator -

http://estlion.com/EGE2000Ti.html

. It's rated at 61dBA, idling, at 7m. Of course it's a poor clone of a Honda EU2200i - I bought this for what amounts to about a quarter of the price of the Honda in my country . For something that's going to run a few hours per year I thought it fits the bill nicely.

We have a nifty automatic transfer switch and a whole-building UPS at the office (which I helped spec and put together with an electrician), but for the house it's a bit overkill plus the location of the CB panels very far away from the yards means running the cable from generator to transfer switch is impractical (this being a house there's no drop ceilings, and our houses are made of stone so no fishing cables behind drywall for instance).

It would be nice to have a whole-house UPS and eliminate the generator entirely, but lead-acid batteries seem to degrade rapidly and like I said, LiFePO4 isn't really available in Malta. Well, there are some marine vendors that offer 12V 100Ah for €1500-€2200, which is a bit steep considering the generator only cost €570.

 

[TugboatEng]

This problem isn't impossible to overcome but needs to be looked at from a different angle. The generator will cool just fine provided you put it in a big enough box. Obviously space is an issue so a fan can be used to make the box smaller. But, use a big, slow turning fan or else it too will contribute to the noise. Baffle intake and exhaust openings as much as possible. Run large pipes to keep velocity generated noise to a minimum.

The cooling required for the engine is equal to the power output. Size your airflow accordingly.

 

[itsmoked]

LMF5000; I feel for you man. Tough spot.

LA batteries do lose capacity quickly. Seems newer ones faster yet, and the weight.. ugh.

LFP batteries have dropped in price a lot recently and new suppliers have appeared. It might make sense to re-assess that route now. Especially with the whole Russian caused gas nightmare you could be having more outages.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[wayne440]

By the way, I am still interested in the "...10-20kg, 7-10kW, <70dB @7m, fits inside a cube of side 500mm, 5 hours endurance, -5 to +50 deg. C operating environment, cost below $5000..." generator you proposed about 5 years ago. Up my order to 2 units if/when you get that done.