Civilise the Generator?

[Guest Bill]

Despite much thought I haven't been able to come up with a viable alternative to a generator for an independent electricity supply. So what about going the other way: muffling the generator to the point that it no longer annoys the neighbours? This thought was sparked by a new product, the Self-Energy (see www.novaleisure.com). Essentially it is a small 2-stroke generator in a sound-proof box, and is claimed to produce only 51dB, just slightly more than a quiet office, and a good deal less than a normal conversation. That should be OK. It burns LPG rather than petrol and has a controller which switches it on whenever the electronics detect that the leisure battery needs charging. That means part of the weight can be clawed back by having a smaller than normal leisure battery. The bad new is that the price is an eye-watering £2500 - far too much for me. Also, the output is 12v only and anyway is not enough to run a microwave, my main reason for wanting an independent electricity supply. But can the basic idea be salvaged? First off, I should positively not want to run on LPG rather than petrol, because petrol is available anywhere, whereas we all know about the hassles of incompatible fittings for Continental gas bottles. Given the cost of converting a 4-cylinder car engine to LPG operation I should guesstimate that at least £500 of the cost is for the conversion. Then that fancy controller must cost a bob or two, and the beast has to be fitted by a skilled technician - not merely plugged into a hook-up. So, just how difficult would it be to make a sound-proof box to contain a normal (preferably 4-stroke) generator? How do you get cooling air in and out without letting the racket escape? I'd be interested in any ideas out there.

[Guest David Powell]

Hi Bill...To start the build plans of this super silent machine, how about a water cooled engine? Quieter than air cooled,and fit the radiator C/W electric fan outside the soundproof box. Just a little idea for starters.

[Guest Clive]

We have seen some super muffled generators, some with great power outputs. But you will never escape from the basic problem because when one has peace and quiet any generator running however well muffled makes continuous noise which is amplified in the heads of those it offends.

[Guest Derek Uzzell]

Bill: The Gasperini "Self Energy" unit has been marketed for several years on the Continent. As you point out, it's not designed to do the same job as a traditional generator, its function being to maintain the charge of a motorhome's 12v leisure-batteries by cutting in and out automatically when the need arises. Besides being near silent, there is the option for the heat it produces when running to be ducted into the vehicle's interior. The selection of LPG as its fuel is totally logical as it permits the unit's motor to be light and quiet and the vast majority of motorhomes carry a gas reservoir anyway. Using a petrol-fuelled motor would have been irrational as most motorhomes are now diesel powered so a separate petrol tank would have been required. Using a diesel-fuelled motor would have increased the weight and the noise level. Connection of the Self Energy unit to the gas supply is said to be simple - essentially the same as connecting up a conventional generator that's been converted to run on gas. There is nothing like the complexity involved in converting a petrol-fuelled vehicle to run on LPG. I don't believe international gas-bottle differences are significant in this instance - in any case, you'd probably find that anyone opting for this system would also opt for a fixed LPG tank. (I note that the novaleisure website contains Self Energy installation details. One of the UK motorhome publications also did an article recently on installing this system - about a month back I think - can't recall which magazine but I'm sure some forum member will know.) I'm confident it would be possible to take, say, an already quiet Honda 4-stroke generator, enclose it in a box that's got plenty of sound-deadening material and baffling inside, add a supplementary exhaust silencer and a fan to push cooling air through the box's interior and end up with near silent running. How big the resultant box would be and whether you could actually lift it is another matter. As you have your fellow campers' peace and quiet uppermost in mind I don't want to discourage you, but I suspect that, having bought a necessarily expensive quiet conventional generator and then spent further time and money silencing it to the Self Energy's 51db, you might end up with a similar cost. Funny thing noise intrusion. People will pay good money to be actively deafened at a motor race meeting, pop concert or night club, but be driven to distraction by the sound of a TV filtering through the walls of the room next door. The posting that started this off mentioned parking at Montreuil Bellay and Chateau Gontier. The expectation at the former location is that you'll have a calm night there - because it's off the main roads and relatively secluded - so unanticipated racket from the kids' motorbikes and a noisy generator has a disproportionally irritating impact. The Chateau Gontier parking area has main roads nearby on which vehicles will clearly be moving 24/7. When you decide to park there, you know you'll get a fair bit of traffic noise at night and the sound just fades into the background. I'm sure that people who regularly use generators rapidly become habituated to the noise and tune it out. If you could put all generator-using folk together out of earshot of non-generator users there would be no complaints. Unfortunately life's rarely that simple.

[Guest Brian Kirby]

I hate to shatter illusions, but 51 decibels is not at all quiet. The normally accepted bachground noise level for affice spaces, i.e. the noise emitted by any building ventilation/ air-con units alone, is 35db. This is to ensure that normal conversations (telephone etc) remain audible, and even that is surprisingly noisy in an empty, unoccupied, building. Then consider that every 3db is a doubling of the sound pressure (it's a log scale) and you will see that 51db is actually quite noisy. If you're in the depths of the countryside at night that perception will be greatly amplified, because the ambient background noise level drops to virtually zero. That's why all those dogs suddenly seem to start barking. They've been barking all day really, but once it gets quiet at night they become the noisest thing around and you hear them from miles away. Unless you're running a generator, that is! Far kinder to all concerned to visit a site when the batteries get low, pay for a hook up, re-charge to the full, and then find another quiet corner of paradise to enjoy in perfect peace. Heigh, ho Brian

[Guest Petec]

Totally agree with Brian kirkby - Although I have lost the details of the appropriate db levels fo rnormal offices etc over the intervening 30 years I did work with the environmental people as a sound measurement technician Measuring the levels produced by a University ventilatioin system. Local residents were complaining about the SOUND/Noise levels - These were found to be well within the alloud limits However the FREQUENCY was at a low level. We solved the problem by increasing the number of blades on the fans - thus the frequency - but also increased the sound level - This was then found to be acceptable For your sound box Try some egg boxes (beware of overheating them) Egg boxes are still used in Recording studios as a cheap way of sound proofing them and cutting out echoes

[Guest Derek Uzzell]

Some interesting noise levels information on www.lhh.org/noise/decibel.htm

[Guest Bill H]

Noisy air conditioning generators. Went to a camp site in the US at one time (very hot). Lady said "You gonna run that all night, cos if you are you go right down the bottom of that field, if you don't run it you can stay up here with us peacefull folk"

[Guest Clive]

Bill, That sums up my viewpoint perfectly! The tough bit to arge against is those people who rely on a mobility scooter to get about, these battery powered devices need charging so they run generators for hours on end. This is not helped by the fact that Motorhomes big enough to carry a generator tend to be operated by us more "mature" folk who have reduced our morgagues to a reasonable level and more and more of us use these mobility scooters as we mature. Its a tough one but for me any generator is still a pain in the proverbial. I cherish peace and quiet. If I have to I will move but that's not always possible at a Rally or camp site where plots are allocated. I have wound out the awning, clipped on the sides, set up the barby and outside loungers, put up the table and the wind break, even filled up the FIRE bucket. Then a group of "mature" motorhomers come along and set up close to us friendly people only to start their generators up the following morning after flattening the batteries on the grass rally site the previous afternoon. Grit ones teeth time again I guess! If these mobility scooters were fitted with say a small 50cc 4 stroke pup put engine then they would only run when on the move. But then DVLC and Gordon Brown would come into the equasion and wreck this idea. Over

[Guest Bill]

All Thanks for your replies. Several of you have suggested that noise is "in the ear of the beholder". I agree. In fact, I once lived near a motorway. At first the noise was intrusive, then I noticed that it sounded much like a large waterfall, and decided to tell myself that that was what it was. End of problem! And why is it that the same people who write to their MP about airliner noise pay good money to go to an air-show? David Powell Water-cooling would be ideal, but I don't know of any water cooled generators on the market, and I should think it would be prohibitively expensive to have one made. Derek Uzzell Obviously the question of fuel type is a matter of personal taste. For myself I like to maintain a very close check on the fuel consumption of any vehicle I own - it can give early warning of all sorts of troubles - so I wouldn't want accessories to draw fuel from the engine tank. I have heard that you can get all sorts of flak for filling a non-propulsive LPG tank from a fuel-pump intended for propulsive tanks - no idea if its true, but why court trouble? Just in case of gas supply problems I carry a little Coleman Dual Fuel camping stove, which weighs only 3 lbs. It burns ordinary unleaded petrol and puts out more heat than a volcano. So I have a (politically correct, EU-approved) jerry-can of petrol with me anyway. I can't see why converting a spark-ignition generator engine to LPG would be any easier than converting a spark-ignition vehicle engine. Petec I like your idea of using egg-boxes for soundproofing. I've seen the same thing used for the ceilings of nightclubs. Conclusion Use the egg-box idea. Only run the generator away from sites or at times when people are up and about, and then only for short periods, e.g. ten minutes while microwaving lunch.

[Guest MelE]

One key problem with petrol generators that few seem to be aware of is that it is effectively illegal to use them in some countries - and Spain is a key one. This is because, in Spain, it is illegal to fill or transport petrol in small cans - whether metal or plastic - so it is impossible to refule the generator legally.

[Guest Bill]

Mel, that's interesting, particularly as Spain is a country I should like to spend a lot of time in. Just one question: is this law actually enforced?