Dear Myles,
I do not have any reservations about using a Sevcon controllers. I have been using them in bench testing for my motors, and will be using one for my own boat when I finish winding the stator. Sevcon makes a robust product. The programming simplicity and stout terminal construction ensure proper installations will be trouble free for many, many years, provided allowances are made for marine applications. Regular ICE's cannot just be bolted into a boat without special considerations, and the same holds true for any electronic system as well.
Regarding open frame motors exposing magnets in a marine environment, I do not recommend them. Microscopic holes in the plating will eventually cause the separation of the magnet from its plated covering. This problem has plagued NdFeBr magnets from day one. The sintered magnet compounds are extremely reactive with water. I've tried nickle, chrome, and even gold plating. I've tried powder-coating, fluidized bed, and epoxy encapsulation. While most magnet coatings stand up well in 100hr hot water salt spray testing, the problem of manufacturing consistancy makes any coating sustible to the slighest bit of contamination. Neo magnets are first compressed into green (soft) forms in a strong electro-magnetic press. They are then placed in vacuum bags and racked into a 10,000psi hydraulic oven. They are further compressed into their final size and density. Once sintered, the bags are cut open, and the magnets are usually plated. The slightest residue of oil,
either from handling or the oil bath sintering proceedure, will soak into uncoated magnet during processing. With hundreds of magnets tumbling in the plating solution, some of the oil inevitably contacts other magnets in minute quanities. Although the plated magnets come out looking just fine, a percentage of them will have flaws, and therein lies the problem. Most neo goes into hermatically sealed hard drives, assembled in clean rooms with near zero humidity. Additionally, there is a getter inside the sealed compartment to absorb any moisture, ensuring the magnets cannot react with any water. I fear thi is not the case with an open frame motor in a marine environment. You may have a set of perfect magnets in your motor, but individual results cannot be considered in reliability studies. While I may be a competitor in the brushless motor manufacturing industry, I am far more concerned with the enviromental liability of producing products which do not
withstand the test of time, as well as the reliability required in a marine application. It's one thing to throw a magnet at the track, or even in daily, driver on your way to work. It is an entirely different situation when you're crossing infront of a container ship in a crowded canal. You lock your rotor up when you go to 100% power, and its an entirely different set emotions. Better have the TP handy...Please ask your motor expert about his or her feelings on this matter, and keep an extra set of oars close at hand. Live long and Prosper, my friend.
Be Well,
Arby
____________
From: Myles Twete <matwete@comcast.
To: electricboats@
Sent: Saturday, August 8, 2009 11:11:53 PM
Subject: RE: [Electric Boats] 4kw "Arby" motor?
Arby-
Thanks for the tip/idea regarding using conformal coat.if I were to consider
that, I'd consult my motor expert first.
But with 6yrs or so now on my Etek brush motor, with nominally 20 excursions
per year, corrosion has not been an issue, period.
Refresh: my motor is bolted with stainless bolts to aluminum motor mount,
with aluminum fan shroud and fan directly connected to the motor with fan
just above the brush housing.
All of this is under the stock outboard motor cowl. The fan pulls air up
thru the motor, vacating brush dust and any other 'stuff' might get sucked
thru the motor. It's probably one of the cleanest motors out there and the
cooling provided allows my motor to efficiently deliver 6HP continuous at
36v.
As regards controller-related failures, I stand by my earlier assertion that
corrosion had nothing to do with 95% or more of the ones I've known about
that have failed.
In fact, I'm being conservative with this number as I frankly have never
heard of someone's controller failing due to corrosion.
I'm being specific here as regards to controllers because you were
specifically raising conern about the 'open header' of the Sevcon
controller, essentially asserting it is an inferior design because of this.
I totally agree that mitigating against the effects of corrosion is
important in any installation and all system elements and may be cause of
most system problems (I wouldn't call these failures necessarily- --however,
corrosion leading to high contact resistance that causes a battery post to
fail would be a failure).
So sure, corrosion is a major challenge.
But please don't imply that any significant number of controller or motor
failures are due to corrosion--- there's just no evidence of this.
Have you posted your Mark I/II/III/etc. controller/motor specs online yet
for us to review? Product that is available to the public for sale should
have reviewable specs if discussed on this forum.
-Myles Twete, moderator, Electric Boats
From: electricboats@ yahoogroups. com [mailto:electricboa
On Behalf Of Arby Bernt
Sent: Friday, August 07, 2009 5:07 PM
To: electricboats@ yahoogroups. com
Subject: Re: [Electric Boats] 4kw "Arby" motor?
So Miles, you're saying if you run hard aground, it means your boat broke?
Allow me to re-phrase my observation:
Most of the problems encountered in carefully installed and tested systems
are related to electro-mechanical interfaces. Magnet corrosion and the
epoxy/plating interface certianly do not fall into this catagory. I'm glad
to hear your motor is still going strong. I would much rather hear success
stories than the problems I'm usually called upon to solve.
You might consider spraying some conformal coating in your motor if it
spends it's life over the water. Very flammable stuff until it dries, so
please be careful. I use plenty in every motor. Consider it preventative
maintenance. Battery terminal spray will help keep corrosion in check on the
battery interconnects and the controller. Messy, but effective.
Be Well,
Arby
On Aug 7, 2009, at 5:12 PM, "Myles Twete" <matwete@comcast. net
<mailto:matwete% 40comcast. net> > wrote:
Arbi offered: "95% of system failures are due to electro-mechanical
interfaces".
Maybe so, but that's not my experience.
And even IF so, 99% of those failures were likely due to operator error or
poor installation- --i.e. poor maintenance or design.
Yes, bad solder joints, bad crimps, unclean or corroded connections are
responsible for high resistance that can lead to poor performance or
failure.
But does that mean we stop using any of these techniques or only ever
connect electrical devices if within enclosures that meet arbitrary Federal
Regulations? No.
But let's get specific.
Speaking strictly of controller failures, as I've followed EV usage of them
since 1993, I'd estimate at least 95% of the failures that I have personally
experienced or read about were NOT due to electro-mechanical interface
issues at all.
Rather, the primary killers are:
. Non-existent pre-charge resistor circuit (sudden inrush into
controller kills bulk capacitor)
. Marginal or non-robust controller design (don't handle brief
overloads gracefully and outputs get fried)
. Insufficient thermal mounting of controller (controller overtemp)
. Incompatibility between controller and load or motor load profile
(eg. running continuously at controller peak rating)
. Blowing up controller by incorrect wiring on installation
I have been running now with a brush motor (ETEK), Curtis or Alltrax
controller, T-105 batteries and have had little or no corrosion issues (a
couple battery connections is all).
While I'm not operating in a salt-water environment, my boat has been
continuously moored on the Columbia since 1996 and operating as an electric
since about 2003. I haven't a clue about meeting any Federal Regulations as
regards enclosures-- -is this an insurance concern or what?
I'd gladly use a Sevcon.and sure, it'd need to be protected from water (as
with my Alltrax), but seriously Arby, unless you are giving up on your
brushless motor and simple 24v brushless controller and instead packaging
Sevcons with brush motors, why are you concerning yourself with a housing
that meets Federal regulations for a controller in your personal private
boat when you can mount your Sevcon in part of the cabin? I'd be very
concerned about trading off good thermal design for putting a controller in
a housing to ostensibly meet some regulation that you already meet by
locating the electronics behind a control panel. Again, contact resistance
issues are only responsible for failures in cases where poor maintenance or
installation are concerned. And that's a tiny minority of brush motor
controller failures. The Sevcon and Alltrax (and other) brush controllers
are excellent controllers and are somewhat resistant to the primary killers
I mentioned above unlike others that are easily killed by mistakes.
-Myles Twete, Portland, Or.
From: electricboats@ yahoogroups. com <mailto:electricboa ts%40yahoogroups .com>
[mailto:electricboa
<mailto:electricboa ts%40yahoogroups .com> ]
On Behalf Of Arby bernt
Sent: Thursday, August 06, 2009 5:23 PM
To: electricboats@ yahoogroups. com <mailto:electricboa ts%40yahoogroups .com>
Subject: Re: [Electric Boats] 4kw "Arby" motor?
Hi Cris,
I would like to test a motor using a 48v Sevcon controller. Brian has
suggested the same. I'll need to prepare a motor for an external controller,
and a housing for the Sevcon that meets Federal Regulations. Of particular
note is the 3/4" conductive sphere test...as well as the obvious corrosion
issues posed with the open header with its plated connectors. My experience
has been that at least 95% of all system failures are the result of
electro-mechanical interfaces. The plated spring bronze receptacles on the
Sevcon signal header and the contactor are fine for dry environments, and
will function fine for testing, but I would never consider them capable of
providing 10+ years of service-free reliability, even with an industrial
strength housing. There are a pair of Electric Wheel motors and controllers
on E-Bay. Have a look at them to see what happens when industrial enclosures
are used in a marine enviroment.
Arby
____________ _________ _________ __
From: Chris Witzgall <chris@witzgall. org <mailto:chris% 40witzgall. org>
<mailto:chris% 40witzgall. org> >
To: electricboats@ yahoogroups. com <mailto:electricboa ts%40yahoogroups .com>
<mailto:electricboa ts%40yahoogroups .com>
Sent: Thursday, August 6, 2009 10:33:44 PM
Subject: [Electric Boats] 4kw "Arby" motor?
I would think a 48v version, perhaps that can run on 24v as well, would be a
hit. Our boat, 10k lbs on paper, and more in real life, would not be
suitable for a 2kw motor, but might get along with a 4kw version.
Arby - if you are reading this - have you looked into the possibility of a
4kw version of your motor?
Chris
On 8/6/09 10:17 AM, "aweekdaysailor" <aweekdaysailor@ yahoo.com> wrote:
>
>
>
>
> We had a sail-in to Treasure Island last weekend which included 4
e-boaters on
> 3 sailboats - mine, Hans K and Kevin brought his Erickson 27 powered by
Arby's
> [http://www.advanced marineelectricpr opulsion. com/] motor. Tomasz and
his wife
> came along on my boat (he's got an e-boat down in Monterey) so I got to
make a
> couple of new friends to boot.
>
> It was a great day for sailing and we hit the tides well (all coming from
a
> different spot on the bay). We'll hopefully get some pictures up soon.
>
> We did have a "watt race" - my boat and the Erickson running parallel and
each
> calling off watt (amp actually) readings. This was all very un-scientific
but
> we did calibrate the ammeters and had independent observers at least.
>
> Downwind, the 100% watt draw advantage (for example I was at 2KW, Kevin at
> 1KW) was pretty close to true. Upwind (about 15kts) it narrowed a bit to
about
> 50-60% fewer watts advantage (i.e. I was at 2KW vs 1.5KW for Kevin)-
making
> sense with that boat being about 30% lighter and a freshly scrubbed hull.
> (Kevin I'm going from memory, so please correct me if I mis-state). We
were
> nowhere near hullspeed - maybe 4kts down and 2-3 back.
>
> I'm still nursing a set of bad batteries, comparing very different boats,
mine
> needs a scrub, props, etc -- so unfortunately I don't place much faith in
the
> numbers - this was intended for fun more than anything else, though I'm
sure
> this will trigger some debates (what's the expected difference in those
hulls,
> etc...)
>
> That said...Arby' s motor is a very sweet package - very clean, compact,
and
> very robustly assembled (so much so I'm afraid pictures taken of my setup
are
> going to end up as "before" pictures like those diet ads in the
tabloids...) .
> In particular, I think the lack of exposed wiring will be a huge advantage
in
> long-term reliability in saltwater installations.
>
> I think more testing is in order before declaring it SF Bay ready for a
boat
> as large as mine (30' 9800lb), but it seemed to me a good fit for the
Erickson
> and for the very large number of boats up to that size/vintage ready for
new
> motors. The 24volt package has obvious advantages as well, though I would
love
> to see 36V and 48V options.
>
> YMMV, Caveat Emptor and all that - but all in all I think it deserves
> consideration as a legitimate option in appropriate sized vessels and
sailing
> conditions. What "appropriate" means will involve further testing,
experience,
> testimonials, etc.
>
> -Keith
>
>
>
>
>>
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