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Forum Index : Other Stuff : Advice generator
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| nickskethisniks Guru  Joined: 17/10/2017 Location: BelgiumPosts: 458 |
Hello, I expect we need some extra energy source beside our solar array. So I want to buy a generator for those extra clouded days. Our power needs are about 7-8kwh/day, normally with our energy input of the solar arra it's enough. Even if I see the total hours of sunlight in december/january there would be enough sun to cover our use, unless we have 5-6 days of dark weather in a row. That's why we probably need a generator, first I was thinking to make a backup battery and charge it at my parents place, they only live 5km away. But that would be to much hassle. So a generator, it would be nice to recover some heat, and use it to heat water for my floor heating? But a watercooled diesel engine is way above my budget at this moment. I don't know if heat recovery is worthwile on the exhaust? I think I need a generator that could sustain about 1kVA continous. Maybe less than 100hrs / winter. Option one: Buy one, diesel or petrol? Closed enclosure or open frame? I suppose open frame is nice for doing maintenance and stuf like that. Maybe more handy if I want to ad some copper tubing for heatrecovery. I was thinking of this one: https://www.hbm-machines.com/producten//hyundai-hy3200sei-generator-invertor-3200w-met-benzinemotor https://www.hbm-machines.com/producten//hyundai-dhy8500ae-t-standby-70kw-dieselkrachtstroom-generator Option two: Make a generator my self, buy a higher quality diesel or petrol engine. Hook it up with a belt to an alternator. This would be ideal but maybe just to expensive: https://www.halvewerk.nl/Webwinkel-Product-94676167/PTM350DPRO-7pk-dieselmotor-(professional-series)-by-Loncin.html This is a better fit for my budget: https://www.halvewerk.nl/ptm-200-professional-19-05-mm-as-e-start What I was asking myself, do they need some kind of flywheel? I have a few 3 phase ac synchronous servo motors, (permanent magnet rotor) that I could easily rectify and put in one of my solar buck converters. @ 2000rpm they give 120hz and +/- 150vrms AC. The right gearing would be needed. I think they were about 6kVA. But I would use it between 500-1000VA. Maybe they give to much vibration because the way they are build. I also have a 5kw 48Vdc 3phase induction motor I could use, but I understand it's verry difficult to get the settings right. Edited 2019-11-22 21:16 by nickskethisniks |
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renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Option two with the second engine should be fine, maybe hook up one or two treadmill motors like here If you can try and get two identical so you can run them as a matched pair if needed. If you have an mppt that can handle higher volts you could feed it with the output from that. Not too sure if it would load it up and make the engine sag or stall. Otherwise just hook them up and not run them full speed Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I am going through all this myself right now. Originally bought an ex hire 20 amp 240v standby generator, single cylinder 12Hp Wisconsin air cooled engine, for $50 on e-bay. The type of thing you often see at building sites. Not working obviously, and there was no carburettor or inlet manifold with it. Anyhow, bought a Chinese carby and it then ran well, but it has to be run at 3,000rpm to reach 50Hz, and being air cooled was very noisy. Rather nasty rope start on it as well. Next step was to fit an electric starter and car alternator, a 12v battery, and a proper (non magneto) ignition system to it. That turned something rather horrid into something much nicer at very little cost. The 240v alternator then suddenly decided to fail due to an open circuit field winding. I could have rewound it myself, but decided to junk the whole alternator and fit a treadmill motor instead. The engine can now be run at only 1,100 rpm and it just purrs at that speed, which is really just a fast idle, and with a huge exhaust muffler, its almost silent. With the garage door shut it cannot be heard beyond. If I was going to do it all again, I would start with a small four cylinder water cooled car engine. That will run very quietly and it will already have electric start, alternator, and probably EFI. When run at low rpm it should last forever and be very reliable. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
What you are saying dosen't seem to add up. 7-8 Kwh day consumption. Want a 1 Kva Generator. Why are you looking at units so large then that could supply your total daily consumption in 1 hour? I think there are cheaper alternatives that would do what you want. Suggestions. More panels. If you can go 5-6 days on what you have, increasing that by 50% should get you through unless where you are it rains for a fortnight solid. In that case double your panels and even if you are only making 2-3 KWH day you will be fine. You should be able to get weather data on the amount of sunny/ overcast and wet days where you are to give you an idea of the reserve you might need. Used panels are cheap and you can put any amount on a charger/ Inverter providing you don't exceed the voltage rating. Charger will take what it needs and be happy. If you have excess you could divert it to other loads. 8 kwh a day isn't hard to make even on a wet day. Just get a cheap petrol Generator. Lots of 2.8 Kw petrol gennys around and you could always pick one up used. Pick up a second for a spare and you are laughing. I have had one of these for about 10 years and had no problem other than the carb leaks if I don't turn the fuel off. It's done some reasonable hours now. Dragged it out the other week after having not touched it for 3 years and the thing fired right up on the petrol that was in it. Filled it up some more and it ran 6 Hours with no trouble at all. When I first got it the thing would run about 6 hours a day most weekends and did that for about 3 years. Only ever changed the oil and checked the air filter. I did also adjust the carb to give the right frequency a couple of times. Get a used small petrol/diesel stationary engine and hook that to a treadmill motor/ induction motor / 48V alternator. You can make an alt from a F&P washing machine motor that will do the output you want well and truly. 5-6 Hp motors are plentiful and would give around 3Kw so plenty of output. Should take around an hour to give you the power you want given you'll only be making up a shortfall. Car engine as Tony suggested. Given the price of that diesel you linked to, you should be able to get a car engine way cheaper. If you need you could get one of those electronic governor kits but as you will be battery charging I doubt you need that much regulation. Even at a fast Idle they would put out 5-10 Hp so you could drive whatever you wanted. For the power you want, I don't know going to the trouble of a co gen system would be worth it. Time everything got warmed up wou'd be ready to shut the engine down. The mean heat output given the running time and fuel burned would not be much either. Otoh, You could use the power the engine was generating and the heat to warm the place. Get a water heater element and put that in the cooling circuit to boost your heat output. Probably only economical if you are running a diesel engine on veg or waste oil. I wouldn't dismiss the small petrol generators too quick particularly if your budget is limited. For the power you need and the time they would be running, with a bit of basic care they should last pretty well. As it seems you might be in the early stages of off gridding, getting a cheapy generator till you get a better idea of what your demands are really going to be would seem wise. No use spending a fortune on an over kill machine. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Mine is only a small system, 5Kw of panels and a 6Kwh battery. Once the sun comes up, the battery has reached full charging voltage in about one hour, and over about the next three hours the charging current tapers right down to zero. There is no real point running a generator for hours and hours just to get the last 1% of charge. Its far more efficient to have a smaller generator and run it at full load for several hours, then as soon as the current begins to taper off, shut it down. The slower you charge, the higher the percentage of full capacity can be reached before the current begins to taper off. So with a 6Kwh battery that is 60amp hours at 100v. A ten amp generator will be quite sufficient as the battery usually never even gets down to even half overnight. A 2.5Hp tread mill motor is rated something like 180v, 10 amps at 4,200 rpm. If I run my engine at around 1,100 rpm, eight inch to three inch pulley will spin my treadmill generator to 2,933 rpm. That is 70% treadmill rpm, which should generate 70% of 180v or 126 volts. Should be just about right to charge a 100v lithium battery to 103.5v. What I don't yet know is how much throttle opening and engine vacuum that represents. Still have some pulleys on order, so have not yet been able to test it. Cheers, Tony. |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458 |
Yes I was planning to add more solarpanels, but I need to spent time to search for them, sometimes there are 250w panels for 50€. That's the cheapest I could find, and another 25€ for mounting stuff/panel. But I need more roof, I don't have anymore space on my house, just on the northside. But that's not something I want to do in the winter. At this moment a generator will be cheaper and if I buy one, faster, the wife don't want me to work at projects the coming months with the new baby. She said "just buy one", we saved 1400€ on gas and electricity this year, so you can have 500€ to invest"... I was looking at bigger units, because they can start on a battery. Would be nice to hack it, so they start when there is a low voltage on the battery. Maybe bigger generators run much quieter at the same powerlevels. I found out I still have a motor laying around... I forgot it completely, removed it 2 years ago in an attempt to convert my lawnmower to electric. It already has a charging coil and electrical starter  Just tested the ac synchronous motor, it likes more to be loaded on all the 3 phases the same way, no vibration then. When spinning with a powerfull cordeless dril, I fed the rectified sinewave in to a heater, that gave me 500w. So not bad. It would cost me about 100€ to buy the right timming belt and puleys. And a weekend of time to weld somekind of frame and put it together.  I think I need to sleep on it for one more night to make a decision. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
That looks like an 8mm pitch timing belt. Many overhead cam car engines use 8mm pitch belt and gears. Typically 24 teeth on the crank and 48 teeth on the cam. Should be able to scrounge something very cheaply from an auto graveyard. Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Saw the Pic and was thinking exactly the same thing. I have a collection of Timing gears and Idlers off cars. They can be very strong. Takes a lot of energy to actuate the valves on a quad cam engine turning 6K rpm. Belts are usually better at higher RPM for the load they can carry but I think they would breeze this in. Belts are changed pre maturely on cars anyway so what would be replaced for automotive use would probably give you hundered more hours use in this setup. You can easily tell the condition just by looking if the writing has worn off and if there are any cracks on the back or missing teeth. They are really shot when they get to that but generally they are worn but not damaged. The other thing you might get cheap from Vehicles is the Micro V or flat multi rib belts. You should be able to get a variety of pulley sizes from different cares, just check if they run 6 or 8 groves. On 2 Pulleys with a tensioner, these things can turn 20HP without much trouble. Being a vertical shaft engine, you'll have to turn the motor the other way as well. You could tension the belt conventional with a slotted and pivot mounting point but these days idler tensioners are on everything and not even expensive to buy new off fleabay. That way you always know the things are going to be right and don't have to worry about adjustments. What is the rating of that Motor? Doesen't look very big and is an unusual layout. Running a 15 Hp engine on that motor even if you gear it up 3:2 looks like it would be pretty severe over kill. Perhaps you could find another larger motor cheap at the scrap yard? I see them all the time at my local place and often there is nothing wrong with them. Easy to check with an ohm meter anyway and if you can get them for a few euro above scrap value, you won't pay very much. I would also look at putting a car muffler on the engine and getting a header made to suit. The OEM mufflers are terribly restrictive for packaging and silencing purposes and do nothing for engine cooling or fuel efficiency. A car Muffler will not only give the thing a quieter note but also let it breathe better and run cooler. The main noise you will get with one of those engines is mechanical clatter. Not easy to do much about on an air-cooled engine but double open surrounds will help. |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458 |
Update, All thanks for the advice, we were really running out of energy @ that moment, so timewise, I couldn't build something myself... So we bought the hyundai hy3200sei generator, really nice unit! We eventually used 147 liters of petrol to suit our consumption during this winter. I think the unit used about a little bit less then 1liter for 1kwh charging. I constantly charged with 20A, that was about the limit "heatwise" I needed to get rid of the exhaust fumes in my basement. I used 2 fans to extract the fumes directly at the generator. Last time I used the generator was @ the end of januari. Days are getting longer now, so I'm not expecting power shortage untill next winter. I finished a shed where I could fit another 10 panels. I started recording all data from my energy system starting from the end of december. December and januari were the worst months, surprise  It's a shame but I only have 1week of data in december, but I had the feeling december was a bit the same then januari. The verdict is that we are generating just a bit more then 60% of our consumption during the worst period. So that is equal to about 15 panels extra, not even that hard. I will keep an eye on good deals on solarpanels @ the end of this year. I hope the price will come down a bit. Allthough I can buy new 330WP panels for arround 140€. Edited 2020-02-17 23:25 by nickskethisniks |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Check your local solar installers and scrap yards for Panels. I'm getting quite a few there now for free. Feel a bit silly that I was paying for them a year ago and getting better panels now for nothing. Should have been making great power here over Jan and Feb but smoke filled skys from bushfires turning almost over night to Clouds that produced floods has knocked generation around quite a bit. If you still want to use that motor for a generator I'd be looking at a small Diesel. Much cheaper to run and if you can find a supply of used veg or even used engine oil, at worst you could blend with 50% diesel and make a good saving that way. The old Lister CS style engines would be good for what you want. Quiet, reliable and last an eternity. Run on any fuel you throw at them. I also have single and 3 Cylinder Kubota's. The singles are reliable enough but I find them quite noisy even though they are watercooled. My latest one, the 3 Cyl 682? I'm in love with. Such a quiet, Powerful compact engine although mines not real smooth. I have an idea an injector may be a bit sub standard. It is smooth enough once the revs get up a bit though. If I was ever going off Grid I'd definitely have at least one of these. They are not cheap but they are brilliant. I'm running mine on veg oil and I'm actually surprised how well it runs on it and I have been using veg a long time. Just purrs along and starts exactly the same as it did on pure Diesel. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
If you really want to make a small engine run quietly, one way to make a very efficient exhaust muffler is to use an old compressed air receiver tank stuffed with fiberglass wool. The steel in these will be at least 10mm thick, and no sound can escape through the walls. There will be a removable inspection plate through which the fiberglass can be installed. These things are heavy, this one weighs just over 90Kg, but it reduces the exhaust noise to just about zero. This looks like an air compressor at first glance, but the big blue tank is actually the exhaust muffler.  Still not finished yet, but I have had it running.  Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
That's a Nice setup Tony. Is that your Wisconsin engine? Is that a treadmill motor you have the Bilge blower drawing through? I use the exact same setup with the turn buckles for belt tensioning on my setups as well. Also car belt tensioners can be good as they are virtually self adjusting and take up the belt stretch. I Took a big tank like that to the scrappy last week. You are spot on, I think mine looked around the same size and was about 90 Kg as well. That's why I dumped it, too dam heavy for what I wanted it for. Mine certainly didn't have the inspection port like yours though. One thing I have worked out is you only have to get the exhaust as quiet as the engine. I'd say that engine would be pretty easy to quieten the exhaust on with a car muffler if one didn't want to utilise the tank as a base like you cleverly have. I'd pretty much bet you'll get a fair bit of noise from that paper filter ( would be a lot worse if it were a 2 Stroke or a Diesel) than you would with any decent Muffler. The lister company had plans for Gravel Pit exhaust which from what I have seen Vids of, are pretty much silent. You bury the exhaust outlet in some Chunky rocks and then fill around them with some smaller ones that still leave escape paths for the gasses. Seems to work very well. I saw some guys in the UK running the exhaust through a generous size plastic Pipe under their garden beds and then up and out through a smaller outlet with a small Muffler. The idea was the larger pipe provides plenty of Muffling area slowing the exhaust down and the heat makes the soil warmer in winter and the plants grow better. Plastic pressure pipe is cooled enough by the earth not to melt or collapse. The exhaust in most engines given a bit of attention to is probably going to pale into comparison with the noise from the engine itself. Not come across an aircooled yet that doesen't emit mechanical clatter and 2 strokes can be a lot quieter in that regard than anything else. I gave the Kubota a run yesterday evening. I actually think it's a bad mount that's making it shake now. Have to see if I can get some new ones. It is a bit clattery as well as expected being an oil burner But at least with a water-cooled you can virtually seal them in a box with the intake, radiator and exhaust on the outside and keep them pretty quiet. Wish I could find some decent belt Drive 240/415V alternators to hook some of these engines I have up to. Seem near impossible to get here at any remotely sensible price. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes, its a 12Hp Wisconsin, it runs at only 1,200 rpm to keep the noise down. All of the noise now seems to come from just the external moving parts, which is not a lot. Measures as 47 dbA at six metres which is the standard test distance for generators. It drives a 2Hp treadmill motor, rated 180v and 10 amps to 3,000 rpm. I fitted a 12v e-bay "bilge blower" to force some serious cooling air through the treadmill generator. That bilge blower is rated 270CFM at 12v, and it pushes a measured 100 CFM through the treadmill motor. You are right about only having to make the exhaust as quiet as the engine. This is probably less, but its also the nature of the noise. Anyhow, pretty pleased with how this has all come together from junk I already had. Still putting it together and still a lot more testing and mucking about yet, but it all looks quite promising so far. Eventually plan to get a natural gas carburetor for it so refueling will never be needed. Final step will be to get it to start and stop all by itself whenever the battery gets a bit low. Its all a bit over designed really, but its been a fun project. The gravel pit idea is something I have not heard of before, and should work well. Another trick is to feed the exhaust down a storm water drain. Cheers, Tony. |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1022 |
That looks like a good setup Tony. I have used old gas cylinders and even an old HWS for a muffler, (for six litre diesel generator) works well and cost nothing. Saw an old powerhouse diesel engine once, massive thing with underground muffler and was half full of water, not sure if it was supposed to be. I have 2 of those engines 9hp each, one has the points on the side of the block the other has the old impulse magneto and was easy to start, also have a V4 that has a great sound but wouldn't run on LPG because of the waste spark would ignite the gas and backfire, it can be fixed, some engines are ok with it. After reading your post I saw inside one of those silenced diesel generators, all the inside was lined with that sound proofing wedge foam, which seems to be cheap enough to sound proof a small gen set. Could end up that quiet you might forget its going.  Cheers Aaron Off The Grid |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I had thought of making a kind of small alcove in one corner the garage lined with that sound absorbing material. Its difficult, because totally enclosing an air cooled engine is not going to work. A water cooled engine would have been much better for this, but I used what I already had, that was part of the challenge, to do it at minimal cost. Its not obvious from the picture, but the short shiny section of exhaust is a slip joint to allow for a bit of expansion and movement. Also some solid rubber tires, with a bit of give, take up any small unevenness in a concrete floor, and prevent any vibration from being transmitted through the ground. Without this, a solid steel base tends to rock and walk around due to the vibration ! In my case, this heavy tank makes an ideal rigid base to bolt down the engine and the generator. Its all rather large and heavy for the small amount of power it generates, but as a stationary never to be moved around generator, that does not matter. Underground mufflers are nothing new, and fairly common on some of the very ancient very low rpm stationary diesels. One or more interconnected brick lined underground chambers is supposed to be very effective. Another way to do it would be to bury a section of large concrete pipe stuffed with old car tires, and a few heavy baffle plates along the length that have only a smallish hole. That works on the same principle as a gun silencer. If building a new home, it would be quite practical to bury something like that under a lawn or the driveway. If made from concrete pipe and old tires it could be buried and then forgotten about. The basic idea is to make each chamber fairly large compared to the volume of exploding gas you are trying to silence. Then have something in there that absorbs the sound energy as it echoes around and beats itself to death. The real secret is to then have a relatively small final exit passage for the exhaust to escape. The escaping exhaust will be almost a steady constant flow with absolutely minimal pulsing, with all of the higher harmonics totally suppressed. Edited 2020-02-21 06:27 by Warpspeed Cheers, Tony. |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Hey Tony, I recovered two treadmill motors from ones in the street, you are welcome to one so it will make running that engine more worth while. 12Hp should run 2 no prob, just need to match specs hopefully, ill see what they are tomorrow. Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
  These are the two I have. I was going to put one on a 3Hp petrol. my solar controller can handle 80A with a max of 150v. So my idea was to slowly ramp up the revs till it gets to maybe 120-130v Cheers Caveman Mark Off grid eastern Melb |
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| renewableMark Guru Joined: 09/12/2017 Location: AustraliaPosts: 1678 |
Hey tony, have you got a photo of the other side, just wondering how to did the pulleys. Edit, i'm in the twighlight zone, when I first looked there was only one picture, now I see both sides.  Edited 2020-03-05 16:38 by renewableMark Cheers Caveman Mark Off grid eastern Melb |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The problem with feeding it through an mppt solar controller is that the controller will discover that the more it loads down the generator, the higher the measured power climbs. The generator, and possibly the engine might not be too happy about that situation. What I plan to try (yet unproven) is to just connect up the generator through a diode direct to the battery, then very strictly control the rpm of the engine and generator with an electronic speed governor so nothing is overloaded with a dead flat battery. For your system, the theory might go something like this: The motor runs at 4,800 rpm with 180v applied and no load. When fully loaded the speed falls to 4,200 rpm at 8.5 amps.So under full load we lose 600rpm at 8.5 amps. When designing the transformers for your Warpverter, I think we worked out that minimum battery voltage ever reached might be 44 volts. So we run the generator at an rpm that just reaches 8.5 amps at 44 volts when its fully loaded. Now if we turn the generator at 4,800 rpm open circuit, we should see 180 volts. If we reduce the speed down to to 1,173 we might expect 44 volts unloaded. At full load 8.5 amps as a generator we add 600 rpm to that. So if we govern our drive speed strictly to 1,773 rpm We might expect to see something like 8.5 amps of charging at 44v, which will slowly taper off as the battery voltage ramps up. Its not a lot of power. 44v and 8.5 amps is only 374 watts unfortunately. But its simple and with multiple treadmill motors may even be practical. Anything else requires a pretty complicated control system to keep both the generator and battery both working safely. I hope to get around this firstly by having a higher voltage battery, my minimum voltage is more like 95 volts, and with the forced air blower on the generator can probably push that a bit harder than the 8.5 amps I assume my generator is rated at. It has no rating plate, so I am a bit in the dark. But through an internet search I think I have nailed down the make and model from pictures and measurements. If it will charge at 1Kw that is more than I need to run the house load with enough extra for battery charging as I only have a 60Ah battery anyway. Cheers, Tony. |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458 |
Tony, why don't you use your simplyfied solar hot water circuit? This should avoid overloading of your motor. And maybe ad a comparator tot check batterij voltage. I would use a buck converter design where I would base the pwm modulation on input voltage (overload motor) and output voltage (overcharging battery). Like my solar buck converter based on a uC. |
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