> Norm - Perhaps I misread the description, but I got the impression that the > boat could run on electric only, without the diesel running. I sent them > an email asking if the diesel motor was mechanically coupled to the prop > shaft or not but they have not yet responded.
Ken-Please let me know what they say. > > > > >> What's more such a serial design as they have does >> not fully de-couple the diesel from the prop shaft >> so does not obtain max efficiency of either the >> electric motor or the diesel. >> > > Norm - It would be an easy matter to install a clutch to decouple the > diesel from the prop shaft, but I don't see how the electric motor would > have any drag if it were not energized. > Ken- But even then when the diesel was clutched in it would not be de-coupled in the way it would with a genset arrangement, where the prime movers rpms and torque are always matched closely to the load via electrical loading, IE the load acts as if there was a transmission with infinite gears almost between it and the generator, so the generator can always run at an optimum point or combination of rpms and torque for that power level. > > >> There are some strange things, as well...using the >> thrusters in regun while under diesel power to >> obtain electric power from them just makes no >> sense at all in terms of efficiency, for example. >> > > Norm - I guess I just didn't get the right part of their web site and > didn't see that. I take it you mean that the traction motors can be used > as generators when the diesel is turning the props. This to me is a very > good way to generate electricity, no belts or side loads. Ken- The way they would do it is have the prop shaft turned by the diesel, then the thrusters (NOT on the prop shaft) be turned by the moving water and those would generate electricity. This is MUCH more lossy that turning generators by the diesel via a mechanical linkage which is what you are talking about I think. > > > >> I do not like using a high voltage battery bank, >> either. It makes more sense to convert the voltage >> so that the battery's can be replaced or the >> numbers of them can be changed without any >> problems (one or more get weak or short) and you >> can have more flexibility. >> >> And the claim that discharging and charging the >> battery's will not shorten their life span is hog >> wash. >> > > > Norm - Yes, that is the case as reported in Home Power magazine. Seems the > 50% of rated capacity discharge floor for lead acid house batteries ashore > is the accepted compromise between longevity and utility. On the other > hand, a submariner on the List reported that submarines he served on > periodically discharged and recharged their propulsion batteries as per > manufacturers instructions. So I guess there is more to it. Ken- Some equalizing is needed, but it is just a fact that using the energy stored and replacing it is going to cause what amounts to 'wear and tear'...if you wanted max life you would keep them in 'float' with an occasional discharge and eqalize. That is not the same as usage. > > Laptop batteries, I have read, if not used, are best left discharged for > storage. Ken- Right if they are LiIon. And charge-discharge can shorten the life of them also...they can take so many cycles from X to X at such and such a temp and that's it, on average.-Ken _______________________________________________ Liveaboard mailing list Liveaboard@liveaboardnow.org To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/liveaboard@liveaboardnow.org The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
