Re: [PSUBS-MAILIST] Interesting item on eBay web siteitem#275822570: X-9 "Y...

[Nick <timely@jps.net>]

As I Said to a P-suber before by me sharing my auction ,if noihing else it spurs
the imagnation to build or try different things .Do what to let you all know
that the mini-kotas that I had weren't varible but could also be controlled by
stepping up or down the voltage.Nick

Captain Nemo wrote:

> ----- Original Message -----
> From: <Subscuba@aol.com>
> To: <personal_submersibles@psubs.org>
> Sent: Tuesday, March 07, 2000 1:28 AM
> Subject: Re: [PSUBS-MAILIST] Interesting item on eBay web
> siteitem#275822570: X-9 "Y...
>
> "Hello Pat,
>  The motor controller is single ended not a H or full bridge as I suspect
> Minn  Kota has and thus my design may be more efficient."
>
> Hmmm. Ya got me thinking now.  I'm using the stock MK variable thrust.
> forward & reverse controller.  Wonder if I could get more power by building
> a custom potentiometer?  Also, my Minn Kota 4HP runs at 24 VDC off two
> twelves in series; wonder if the lower end would survive 36 volts (an extra
> 12 cut into the system for short term "burst of power" operation).
> >
> >" QUESTION: Can you tell me the voltage and current ratings of the
> "Monster"?"
>
> She's 36 volt direct current from three / twelves wired in series; but I
> don't have any other specs off the top of my head; and I can't go to MK's
> site right now.  But if you go to their website, they've got a lot of info ,
> including the specs for (I seem to recall) three (?) variants of the 101#
> thrust unit.
>
> >" Do you have to limit initial current surge to prevent stator
> demagnetization?"
>
> I'm not sure if demagnetization is the problem / reason, but I believe
> that's how the stock MK controller is designed to work.  Kind of "eases" the
> juice to the motor to keep her from balking under load.
>
> "I assume the motor is effectively shunt wound with a permanent magnet
> stator."
>
> I think they (MK) all are, aren't they?  It's been a while since I opened it
> up, but as I recall it's permanent magnets mounted inside the case; the
> armature rotates in the field; and there's two fat spring-loaded brushes
> (that the MK techs say will work even with the case flooded, though the
> brushes will wear out a LOT faster).
> >
>
> " I presently have three 12 volt batteries and can drive a 36 volt motor but
> I doubt if the speed increase would be worth the decreased battery run time.
> Still it would be interesting."
>
> (I'd like a little extra speed at times, myself.  For some reason,
> spectators expect to see the NAUTILUS running at high speed with decks
> awash.  (heh!)  I've thought about everything including a jetski
> squirt-drive; but that's a big modification, and I'd have to do surgery on
> my hull.  Just don't want to do that to this boat.  More E-motor would be
> nice, though.)
>
> Are you talking about rigging your present 24 VDC motor to accept another 12
> volts?  This is what I was wondering about above (and frankly, I'm also
> wondering if this and a little tweaking isn't how MK came up with the 101
> Monster.  If the motor can handle the juice, it seems maybe they could
> reduce overheating to acceptable levels by swinging a tamer prop.  That and
> some resistance changes to the controler, and there you go: 36 Volt, 101#
> Monster.  (I don't know this for sure, but I sure am wondering.)
>
> Think I could put 36 volts through my 24 VDC 4HP without overheating the
> lower end (too much) or frying the controller?
> The lower end windings and brushes look pretty heavy duty.  If I buy the
> Monster (and I'm planning on it), I may experiment with this.  Whatayathink?
> Will I melt it or not?
>
> " Ken Martindale
> >
> > PS Don't forget I have a wet sub."
>
> A nice one, too!  Send me some pix!  ;-)
>
>  Pat