I agree with you concerning the prebuilt system. If I had thought that I would be spending as much as I did I might have saved up and got something from a vendor. Things seem simple until you get in the middle of it.
V8 in a 914!? I could barely get my hands in mine to change the plugs!
--- In electricboats@yahoogroups.com, "Eric" <ewdysar@...> wrote:
>
> Tom,
>
> My glib answer was going to be to set the "noise" parameter to 0. Maybe putting in a negative value would make the controller absorb some of the noise from other sources. :)
>
> As a customer of James, I'm aware of the effort and complexity of these issues and what he's gone through to optimize his system. I would say that the simpler controllers have fewer parameters to mess with, but some attributes like the hum (whine) of a PWM controller can't be adjusted away. The Gen4 is way more flexible but requires more technical expertise and equipment to optimize it.
>
> It's kind of like the changes to the cars that we drive. There wasn't anything I couldn't do to tune an engine with carbs. I even tweaked an older analog fuel injection system by hand. But the last few cars that I've bought go directly to specialists for whatever work they need. I get my "tweaking" fix with various projects like my Porsche 914 V8 conversion that I've been messing with and upgrading for 20 years and a stock 1915 Ford Model T that has been in the family since the early 1960's.
>
> I think that buying a tuned electric drive system for my boat has put me way ahead of where I would be if I did it all myself. After converting a couple of cars to electric over decade ago, I've got the basic expertise, but that experience is what turned me towards a complete system with support. I'd rather be sailing than spending time messing about with the drive.
>
> Don't get me wrong,I know that most DIY systems are perfectly functional and work fine just bolted together. However, I think that the complete systems offered by the various vendors here are more predictable and might be considered better, depending on the judging criteria, i.e. noise or efficiency.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "Tom" <boat_works@> wrote:
> >
> > Thanks for the scoop, James.
> > If I didn't already have a $450 MillipaK, It'd be easier to pay out $595 for the new Gen4. But that will have to wait.
> >
> > PS: At idle, the MillipaK draws a lot less than 750A. :)
> > -Tom
> >
> > --- In electricboats@yahoogroups.com, James Lambden <james@> wrote:
> > >
> > >
> > >
> > > There are about 100 variables to characterizing a controller for a
> > > certain motor.
> > >
> > > I was present when the Sevcon Engineers characterized the Gen 4 for
> > > the Mars 20 turn, 28 turn, and double stator 28 turn motors.
> > >
> > > They run the motor on an oscilloscope, spin the motor as a generator
> > > to find out its voltage to rpm constant, and input other variables
> > > from the electrical design of the motor.
> > >
> > > There are error control loops for past, present and future operation,
> > > each weighted differently. Change one variable too far the wrong
> > > way and the motor will not perform, or act like a speaker, or hickup,
> > > or vibrate.
> > >
> > > I characterized the Gen 4 for the double stator motor myself, and had
> > > it running fairly well, but notice dramatic improvements when
> > > Sevcon's engineers did the characterization process. Its a very
> > > difficult task and requires specialized training, not to mention the
> > > software to make the changes. And then the program is tested on a
> > > motor hooked up to a dyno....
> > >
> > >
> > > James
> > >
>
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