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Forum Index : Electronics : cleaning the output of a gas genny
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| petect Newbie  Joined: 03/02/2018 Location: United StatesPosts: 15 |
Hi all Is there a way to clean up the output of a cheap gas non-inverter alternator? The unit that I have puts out about 3.5 kW and has (2) 120v, and (1) 240 v outputs. For electronic devices I can use the alt. to charge a l.a. battery and run a psw inverter off of the bat. (Not very elegant, but it works) I’m mostly concerned about my well pump. It works when powered by the alt, but I suspect it isn’t very happy with the alt power. Since the pump would be $$$ to replace, I don’t want to take any chances with damaging it. The pump draws about 6 amps @ 240 v. I’m hoping that someone can point out a device(s) on ali / ebay that I can run the alt output thru without too many mods so that I end up with something like an inverter alt. I don’t need to clean up the entire output of the alt, just enough to run the pump. Thanks in advance. Pete |
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LadyN Guru  Joined: 26/01/2019 Location: United StatesPosts: 408 |
Hi Pete! The noise is from harmonics. The dumb way to remove harmonics WITH 30%+ (a lot) of power LOSS is to design a low pass filter to let the fundamental frequency through. The dumb way also cannot control the fact the cheap motors change their RPM on loading and that changes the fundamental frequency anyways. So it's a no win game you see. Thus simple way to remove harmonics WITHOUT losing much power is to make the noisy power go through an inverter. The famed honda gennys do that and here is my proposal to do the same, check it out https://www.thebackshed.com/forum/forum_posts.asp?TID=11198 DIY! What motor does the pump use? If it's a universal motor you have a solution that will cost ~$10 If you are in San Diego I am happy to help you locally |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Pump should run fine on a noisy supply. A lot of the noise comes from sparking at the slip rings which looks awful on an oscilloscope. But with an inductive load, none of that matters, the current waveform should be a lot smoother than the voltage waveform. The only disadvantage of the old type gasoline generators is they have to run at constant fairly high rpm to generate the rated 50Hz/60Hz frequency, usually 3,000/3,600rpm which is quite fast. Lots of noise and vibration, lots of gasoline, even at very light loads. The modern inverter generators just generate high voltage dc to drive an inverter. At very low loads the thing can run at pretty low rpm throttled right back, and still have full rated output voltage and frequency. As you load it up, the throttle opens and the rpm rises, but the output voltage and frequency do not change. Much more efficient at part load, less noise, and lower gasoline consumption. It should suffer much less wear and tear and last longer too. A big step forward until something electronic goes wrong with it, then it becomes a lot more difficult and potentially more expensive to repair. These often use very expensive sealed electronic modules that are unrepairable. The manufacturers don't want you to repair them, they would rather sell you a whole new generator. Cheers, Tony. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
I am actually curious about why cheap gennys have such BAD noise. Is it just due to slip rings? I have barealy started to learn about this but someone on the internet (I FORGOT where) remarked it was primarily due to inferior magnetic materials and inferior windings. I would love to learn more To paraphrase what you said, in order to maintain the 50Hz/60Hz output frequency, the cheap gennys have a high idle usage? I believe this is solely governed by the "governor", so hacking the governor to reduce the idle speed on low loads should make the gennys sip fuel instead of drink it? (ignore that this would change the 50Hz/60Hz output frequency for now) OR - we use the chepaest gennys out there, hack the governor to fix the high idle issue and feed the noisy power to a load sharing Warpverter What say you all? |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Inferior magnetic materials ? Cast iron and steel are excellent magnetic materials, cheap too. If the crappy generators are made of some other kind of material I would be very interested to learn what that might be. Inferior windings ? Not sure what that means, I have only ever seen copper windings in any kind of generator or alternator. I have seen aluminium windings in really cheap stuff like microwave oven transformers, but never in a rotating machine. If you put aluminium windings into a rotating machine, it would have a very big impact on the efficiency due to the much higher electrical resistance. So much so, that everything else would need to be scaled upwards in size to compensate. That is just not going to be a cost effective design, so its never done. Brushes and slip rings that carry significant current have a terrible time maintaining perfect electrical contact across a rubbing surface. There is always some visible arcing and sparking going on, and that does not really have much of a bad effect as far as functionality or efficiency goes. There is not really very much you can do about it anyway. Its only if you put a radio receiver right near it, or look at the supply on an oscilloscope you realise how much high frequency garbage there is. But in the real world the problems are more imagined than practical. Cheers, Tony. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Hmm, so for generators that don't use an inverter, except for differences in a filter circuit (or lack of it), the output waveform will look very similar (noisy) regardless of who made it? I ask because there are very very cheap sub $100 chinese gennys that output 2kW continious while a 2kW "made in USA" model (non inverter) easily costs $2k. Neither of them have much of a filter circuit, neither use an inverter but word is that the output from the $2k is of "higher quality" than the sub $100 chinese gennys. I saw a video somewhere that compares output waveforms that does show less harmonics but I just cannot find that video to show you :'( |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Ah ! But they are genuine American watts. No true patriot could ever suffer inferior Chinese watts. My own generator is a 5Kw (12Hp) Wisconsin single cylinder made around Circa 1970 in the good old USA, back in the days when "made in America" really meant something. These days, chain saw motors, lawnmower engines and generators are all made down to a price, no matter where they are supposedly manufactured. Very likely assembled in America by minimum wage labor from all Chinese parts. It probably has a big American flag on it, and an eagle, which truly justifies the other $1,900. Seriously, I once rented factory space, and the factory right next door used to receive container loads of really expensive looking plumbing fittings from China. Beautiful tap sets for bathroom, laundry, and kitchen. There were a gang of minimum wage slaves stuffing them into cardboard boxes with "made in Australia" printed on the box. No doubt the boxes WERE made in Australia, but definitely not the contents. Probably perfectly legal too... So a fifty cent Chinese shower fitting suddenly becomes worth $79.95 retail, because there is a bloody kangaroo on the box. Cheers, Tony. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
You know, I just wish there was a more efficient way of turning cheap gas, propane or LPG into electricity without using an ICE with its less than 40% efficiency |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I suppose it depends where you are. But in my state we have very cheap natural gas by world standards, and that is what I plan to use eventually with my 5Kw generator. No need to store gasoline, and the natural gas just comes in an endless supply without needing to refill anything. If the fuel is cheap enough, thermal efficiency becomes irrelevant. What can get expensive though is frequent rebuilds of the generator if it has to run continuously. Something running for 24/7 might need pulling completely apart every couple of years. Cheers, Tony. |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Tony, spoke with my dad and elder brothers at dinner tonight and they said that the $99 gennys are built as throwaway and it does not make sense to rebuild them as parts and service manual are hard to come by and its just cheaper to buy a new one. It seems like the $99 gennys last a thousand hours or so and cant be run continiously for more than 4 hours. Apparently the "made in USA" ones have parts easily available, come with service manuals and can run nearly 8000 hours before it needs to be rebuilt. Also, there are dealers that will rebuild them and include a warranty. However, they cant be run continuously for more than 10 hours. Is that worth the 20x price increase though? The runtime is only 8x better so how does the math make sense? They did say the output from "made in USA" ones are "way better" but again, I DON'T have a $99 genny to put a scope across. I am skeptical. Never seen these gentlemen ever run a $99 genny here so all info is heresay I suppose. We dont get to enjoy natural gas where we live as we are in the farm. The only connection from the county is water and electricity. Not even sewage or paved road! What generator do you use that can run 24/7 and needs a rebuild just every couple of years? I'm really interested and would appreciate some insight! I would love to have my brothers wind some transformers for me than rebuild engines and they do that every year or less :D |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
I don't know about cheap Chinese, or even the good "made in USA" generators. But my experience at a couple of the Australian Antarctic bases, where ALL of the power comes from heavy duty commercial power generators running continuously, is that there are always at least two generators run alternately, perhaps one week on, one week off for oil and filter changes. Then each year the diesel mechanic has the enjoyable task of completely overhauling one of the main generators. It comes completely apart, and anything that measures or looks worn gets replaced, including cylinder liners, pistons, crankshaft, or cylinder head. If you think about it, 24 hours x 30 days x 12 months = 8,640 operating hours per machine over two years. If that was in your car and you averaged 30Mph it would be over a quarter of a million miles between rebuilds. That is pretty frequent, I am told the big diesel trucks do about twice that before the engines are totally stuffed. But the generators cannot be run until they are totally worn out, they need to go on and on for year after year, sometimes decades. Down in the Antarctic, the diesel generators are truly life support systems that provide not only power but heating and rather limited (melted) fresh water. Cheers, Tony. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513 |
eg8010 frontend You could rectify the gen output and stick something like this on its output. ..if you really worried. .. sort of like they do with inverter aircons etc... but obviously not as " smart ".. Actually you could also beef up the output/input caps to help clean up the gens output without to much loss... I think it works !! |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Having been in Hobart (Australian Antarctic base headquarters reside there) recently I was told that *none* of the IC motors in Antarctica run on diesel, they are all petrol. Reason being, diesel freezes, petrol does not. This is second hand info BTW but makes sense to me.. Klaus |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Tinker, when I was down there the head office was here in Melbourne, but moved down to Hobart a couple of years later. I can tell you for an absolute 100% certainty your source is dead wrong. Its still diesel down there for power generation and always has been. There are two very important reasons for that, the calorific value of diesel is far higher than petrol, and the fire risk is a lot lower than petrol. I spent a year at Macquarie Island (1972) and a year at Davis base (1974) both had a pair of 45Kva Ruston Hornsby diesel generators and a Lister 15Kva backup in a separate building. These were all 1,500 rpm with four pole alternators. Some time since then possibly around 1975 ? these were all replaced with Caterpillar turbocharged high speed diesels that run at 3,000 rpm, and many old hands thought that a retrograde step, although the power output was about three times as much as the old machines. Those same generators are still running today and have been every day for probably 24 years. Anyhow its all diesel, and it does not freeze. At Davis it went as low as -40C and it still did not freeze the fuel. There is a limited amount of petrol but its only used for some light transport such as motor toboggans and things like portable generators and rock drills. There is also a limited supply of jet fuel for helicopters during the summer months. All the petrol and jet fuel is in 44 gallon drums, the diesel is delivered in bulk via a floating hose from the ship. I vaguely remember that long in the past maybe around 1940-1950 some diesel fuels refined in some countries would turn to jelly at very low temperatures, but modern diesel these days does not freeze. So there is some truth in the story you heard, but its not a problem for Aussies in the Antarctic, and never has been. http://www.antarctica.gov.au/living-and-working/station-life-and-activities/power-generation Cheers, Tony. |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Here in USA your best bet is to get an old Onan inverter from the 70seventies they run at low RPM and last literally forever like warp speed was saying repair whatever is worn every couple of years you're good to go be warned i am good parrot but Dumber than a box of rocks |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
Workspeed your wisdom is greatly appreciated seems you know exactly how this world works these days whatever happened to those good old days when a man's word was as good as gold respected your elders Elders was a valued commodity of the community of wisdom patience and understanding when a job paid a living wage and the person working a job had pride in their work seems like that old machinery well Outlast us and our grandchildren if I only halfway taken care of I found that if you give a little bit of respect and take the time to listen so much wisdom just by listening to our elders Love peace good health and happiness to all be warned i am good parrot but Dumber than a box of rocks |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Thanks Tony, for clearing that up. It seems I fell for one of these 'tall' stories the tassies are fond of telling. I 'almost' signed up for an Antartic stint when I was younger but chickened out in the end  Klaus |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
High temperature fuel cells can do it, but they are only prototypes really and have too many problems. A startup tried to commercialise them ( "BlueGen") but failed and closed down. Pity...looked good for a while, a fridge-sized unit would run silently and power the house load and also heating...AFAIK the prototypes failed after a year or so in service and cost way too much to replace. EDIT - That was some time ago, it looks like there is an ongoing 1.5 kW unit as a commercial product, I don't know what the reliability is like now or the arrangements are to buy them. Dr Google has more :) |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The first time I went down, it was a bit of a shock, I only had one weeks notice and none of the prior training everyone else had. I did not know it, but I was at the top of the short list, and someone else pulled out at the very last moment. At the time, I was a year short of the minimum age too. Suddenly found myself in the Antarctic in charge of a radio station and two very much older radio operators. It was all morse code back then, and all the radio equipment full of valves. I did not know morse which was a bit of a problem, but having been a radio ham since I was sixteen, so no problem with it all technically. It was a real personal challenge and all jolly good fun. I cannot have done too badly because I applied to go down again two years later. By that time teleprinters were in full use to handle all the traffic, and there was very little morse code by then. Today its all satellites, and the internet, vastly different to pecking away at a morse key and battling fading and atmosperics and changing frequency up and down over the HF band trying to maintain contact with the other bases and with Australia. There was plenty of adventure for a young bloke back then, and good pay too. There were mining companies in New Guinea and in Western Australia constantly looking for people. Cheers, Tony. |
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| petect Newbie Joined: 03/02/2018 Location: United StatesPosts: 15 |
LadyN I don't know what type of motors are used in submerged well pumps, but I'm pretty sure they aren't universal type. Thanks for the offer to help. Is Connecticut too far ?  Pete |
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