R Cubed Posted May 21, 2012 Share Posted May 21, 2012 (edited) I have to admit to having one of them nasty little cheep 750watt portable generators, which now does not maintain a steady 230-240 volts more like 280-310 :mad: anyway I have striped it down to find the fault and was surprised to find no electrical connections to the rotor, no brushes or sliprings, but it does have windings on it but thats it. The windings are in two halves, having two ends each, one end of each half is connected to an end of the other half except one pair of ends each run through two diodes and there is also a resistor in there tooo. Any idea how it regulates the voltage. :embarrassed: Here you can see the two halves. Two diodes and a little resistor tucked in under the diodes. Got the diodes and resistor set out, here you are what do you all think then ! Does this have some effect on limiting the magnetism in the rotor ? The numbers on both of the diodes is BY 255 the resistor colours are Brown, Green, Orange and Gold which looks to be 15K ohms. In carrying out some electrical tests on this little setup I have discovered that the two diodes are in series with each other and accros the outer ends is the 15K ohm resistor. The resistor tests out ok giving a reading of 14.95 K ohms. the two diodes however are a different story testing each one in reverse you get infinity, which is what you would expect, testing the correct way there is a reading of 11.60 K ohms and the other one give a reading of 12.15K ohms. Is this right ? Edited June 9, 2012 by R Cubed Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted May 21, 2012 Share Posted May 21, 2012 Engine speed? Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 21, 2012 Author Share Posted May 21, 2012 Engine speed? Governed to a set RPM. Quote Link to comment Share on other sites More sharing options...
philb Posted May 21, 2012 Share Posted May 21, 2012 I had one too. They're just about OK to run a couple of light bulbs but not much else. It is, as you say, a brush-less design and as a result the waveform is terrible and the regulation almost non-existent (loosely coupled to engine speed). It just about beats a poke in the eye in the grand order of usefulness. Don't run anything sensitive from it, the potentially very high voltage peaks could kill it. I christened mine "the worlds worst generator" and sold it. Quote Link to comment Share on other sites More sharing options...
Essex5 Posted May 21, 2012 Share Posted May 21, 2012 Silly question, but is the 280 - 310 V on no-load? If so, what is the voltage under load? Is that one of those little two-stroke jobbies? I've got one - not impressed with the internal view - looks as though the coils are wound by hand!:shocked: I suspect that there is no real regulation of the output, it just come out about right if you're lucky. John Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 22, 2012 Author Share Posted May 22, 2012 Yep sorry to say it is a 2 stroke thing... Before it had a problem and fried some phone chargers it was fine you could load it up and the voltage would stay within a couple of volts of 235 ish after the frying incident it would produce the 280-310 ish off load if I then lowered the revs you could get the volts down but as you loaded it more the volts dropped away so I have to be careful not to switch off load otherwise the voltage climes again..... Cant see anything else which might regulate the voltage there is nothing on the outer windings that I can see unless its inside them :mad: All I can think is that those two diodes and the resistor must affect the magnetic field generated somehow. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 28, 2012 Author Share Posted May 28, 2012 Towards the end of the season had another problem starting it and some times when it was running it would cough and then just peater out and die :mad: Tracked this fault to the very nafffff crankshaft seal just behind the generator, it seems to be an ordinary push in liped seal but there is no way of holding it in its place, should be a press fit, not a press fit any more :mad: So with the crank pressure as its a two stroke its enough to blow it out up the shaft so you get no crankcase pressure to push fuel/air up into the cylinder and it wont start....... So if you have problems with yours try looking at this seal it might be the problem, when I get a chance will try to post some more pics. Quote Link to comment Share on other sites More sharing options...
alixcompo Posted May 29, 2012 Share Posted May 29, 2012 Yep bought one of them for £70, fried a £300 leisure battery charger in my motorhome and so slung it as far as possible.. Useless. Pah. Quote Link to comment Share on other sites More sharing options...
robin craig Posted May 29, 2012 Share Posted May 29, 2012 I know we are are frugal or value minded these days, and boy oh boy we have such a choice of off shore products to choose from. Sadly, I know this all too well as management loves to buy deals. We have a Kipor diesel generator that had a battery not much bigger than a one man compo ration pack and would not start unless it was used an hour ago and it was above 20 degrees C and used almost as much oil as diesel. We modified the machine so that there were a set of forklift quick disconnects on the battery leads and use a conventional decent quality battery in its static location now. The leading generator maker in my mind for small units is Honda and I would challenge anyone to beat the quality of their units and the cleanliness of the power produced. R Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 29, 2012 Author Share Posted May 29, 2012 I know we are are frugal or value minded these days, and boy oh boy we have such a choice of off shore products to choose from. Sadly, I know this all too well as management loves to buy deals. We have a Kipor diesel generator that had a battery not much bigger than a one man compo ration pack and would not start unless it was used an hour ago and it was above 20 degrees C and used almost as much oil as diesel. We modified the machine so that there were a set of forklift quick disconnects on the battery leads and use a conventional decent quality battery in its static location now. The leading generator maker in my mind for small units is Honda and I would challenge anyone to beat the quality of their units and the cleanliness of the power produced. R Yep quite right, or go down the route of classic vintage with a lister, at least it will go on for ever but cant lift them, oh the dilema.:cheesy: Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted May 29, 2012 Share Posted May 29, 2012 I thought you had one of those Hiab thingies? Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 29, 2012 Author Share Posted May 29, 2012 I thought you had one of those Hiab thingies? [ATTACH=CONFIG]62360[/ATTACH] Yes........but..................... those generators arnt the thing you can just pop in the car and take somewhere..... Although very usefull.. You poping down to the show over the weekend for a look round ? Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted May 30, 2012 Share Posted May 30, 2012 (edited) ...You poping down to the show over the weekend for a look round ? Sadly I can't, pity as I've heard there will be a 'modified' CCKW worth inspecting - apparently the guy made up a neat manifold out of a piece of what he thought was scaffold tube, but then realised he'd just cut up one of his machine gun mount tubes :whistle::-D Edited May 30, 2012 by N.O.S. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted May 30, 2012 Author Share Posted May 30, 2012 Sadly I can't, pity as I've heard there will be a 'modified' CCKW worth inspecting - apparently the guy made up a neat manifold out of a piece of what he thought was scaffold tube, but then realised he'd just cut up one of his machine gun mount tubes :whistle::-D :rofl::rofl::rofl::rofl::rofl::rofl: Quote Link to comment Share on other sites More sharing options...
alixcompo Posted May 30, 2012 Share Posted May 30, 2012 I thought you had one of those Hiab thingies? [ATTACH=CONFIG]62360[/ATTACH] I think you can get pills for that....! Quote Link to comment Share on other sites More sharing options...
R Cubed Posted June 7, 2012 Author Share Posted June 7, 2012 Got the diodes out see the first post. Quote Link to comment Share on other sites More sharing options...
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