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About Mikexx

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  1. Many thanks for the replies. I'm able to cut and if necessary weld to fabricate a flue. Its not obvious from websites how I can join single to double, and double skin to double skin. Are there standard interfaces? Are the ones in my photos standard? The internal roof has a wooden lining nearby, hence the need to have a short section of a double skinned chimney for a few inches below the ceiling and a couple of inches protruding above the roof; to which I would like to have a demountable double skin chimney to have a reasonable fire draught . It's important to remove as much of the external chimney as possible for clearance under bridges, trees etc.
  2. I have two parts of a chimney, one single skinned and the other double skin. The stove flue size is 5" and the aperture in the roof is 175mm, a little less than 7". I understand it is typical to have a single skin inside the boat for maximum radiant heat, and to have the double skin through the roof and outside. Whilst that works for the two parts I have, the flue protrudes too far for my liking and is a recipe for disaster waiting to happen for hitting bridges and the like. In short I would prefer the external flue to be removable whilst I am on the go. To reduce cost I would like to use what I already have, but I would be grateful for a steer of a way forward. I have included photos of the parts I have. The dual skinned flue is 1.0m long and the shorter flue is 400mm.
  3. It is normal practice to have the negative battery lead bonded directly on the engine or the relevant terminals on the starter and alternator. Rather than relying on a conductive path through/along the hull. For info, there are starter motors and alternators where the negative terminal is not electrically connected the respective bodies.
  4. Your post mirrors the consensus in an earlier topic.
  5. I take your point and the/my misunderstanding. I was trying to say that max torque with a standard winding, would be the same torque as a modified winding. As you say, and I agree, the max torque with the standard winding may never be achieved for a slow revving engine/camshaft drive.
  6. I'm 'shocked' that a surveyor would advocate the removal of anodes.
  7. Droitwich? However, my dipstick touches the bottom of the sump and so without knowing the correct postion my policy is to keep a level over the max mark, so if you looked at mine I feel you'd be none the wiser. My dipstick is at the front whereas I beleive some are in the middle. I am intrigued at your conclusions (with respect to bottom of the sump!)
  8. My boat has one of these: This might assist: I see iit can discharge up to 3m above its base. To be honest, I have never heard of a macerator on a boat. They're a plmber's nightmare at the best of times!
  9. I'm still not sure where my argument is flawed. If there is any misunderstanding I apologise. I do feel the need to point out that in generall the higher the rotor speed the higher the output for any given star or delta configuration or number of turns, up to some aymptotic output. As you say the potential for the original to produce more at higher speed is only relevant if the increased speed is achievable. I think the diagram below best illustrates the difference between an alternator with a set number of stator turns and another with twice the number. Changing from delta to star will be similar, except the improvement in cut-in speed with be sqrt(3) and the max current for star configuration would be 1/sqrt(3) of delta. What the graph does show is that at some point in speed the alternator with the lower number of turns will have a greater output.
  10. Can you be a bit more specific about charging voltage? At 13V I wouldn't expect any charging, and at 14V it would take some time to reach fully charged, though fine for on mains or solar. Is this 11.5V at the batteries or at your TV? If at the batteries I would check connections and make sure they really are getting charged. Then you might have to consider another set?
  11. I don't believe so. The original quote " Your analysis above is flawed as the entire point is to get more power at slow speed". I have already said the 'cut-in' would be lower which means the alternator will be producing current at lower revs where it wouldn't have before. Given power is proportional to current at a fixed voltage I still don't see the 'flaw'.
  12. My apologies, I had believed you might have rewound them. I would have thought that star would be the default winding as you need less turns for the same voltage-current charateristics. By either using more turns, or changing to star, you are inherently creating a higher emf, which will provide a lower cut-in rpm and so start charging at a lower rpm. I'm not sure of the flaw in my analysis. After conversion, at higher revs a star stator should be producing 0.57 [1/sqrt(3)] of the current that would be produced in a delta configuration.
  13. It is a strange set of affairs. I have wondered if the owner would be able to fit a manomenter for the BSS inspector, and do the spray/leak test after refitting the test point. That way the inspector doesn't have to 'work' with gas but has been able to view the process from start to finish and estable 'tightness'. He doesn't even have to supervise the process, just view it. A bubbler wouldn't see a high pressure side/regulator leak either.
  14. If we establish that we are trying to 1/2 the cut in speed through twice the number of stator turns with 1/2 the wire diameter, then: Instead of a 100Amp alternator we have a 50Amp. 1/2 the amount of power is being 'created' at 12V at 1/2 speed. So the torque should be the same at the new cut in rpm as per old cut-in rpm (give or take). If the copper diameter is 1/2, then I^2 R losses will be the same as current will now be 1/2 the old current. I am neglecting thickness of insulation which will be nearly the same for either winding. The inductance of the stator will be 4 x the old inductance (from twice the number of turns), but twice the emf at any rpm, so above cut-in speed, such we should have half the phase current in each winding. I am aware that delta windings have significant third harmonic at the star point, such there are sometimes two further diodes are added to 'catch' this extra energy at high rpms. I would also have thought you would keep the star configuration if it was already there, or make your new alternator star and reap the advantage?
  15. The two main losses should be copper losses and iron losses. Copper losses should be a function of current and resistance, and iron losses a function of field and rpm. I would have thought the torque, all else being same, would be the same but start drawing a load at a lower rpm?