Motor noise---sigh…
For those of you who've done conversions & spent time on the water with them, you pretty much know where noise is coming from.
And for the rest, there's speculation.
Inboards will be subject to different noise factors than outboards due particularly to coupling of noise to the hull.
Traditional series-wound radial-flux motors with built-in fans will have some fan noise.
Axial-flux motors (e.g. ETEK, Lynch, Perm, etc.) don't have built-in fans, but the armature windings themselves spinning at-full-radius in the air gap act as a fan. These motor-driven fans or pseudo-fans generate sound frequency proportional to the speed of the motor.
There are other sources. In my case, I have my ETEK directly coupled via aluminum duct to a quiet Papst 48v axial vane fan. These are awesome fans and I've had one mounted to my ETEK now for nearly 11 years. It has been directly wired to 36v (now 32-48v w/Lithium pack) and so its noise output does not fluctuate at all with motor speed (though I'm thinking I may change that to be driven by the motor voltage instead).
There is coupling noise: In my case, a 7/8" keyway to spline coupler that drives the driveshaft. Being made out of a lower unit pinion gear (pinions still on it), its spinning also acts like a fan and may generate noise.
There's lower unit noise.
All together, in my case, you can hear the Papst fan with the engine cowling off, but that's attenuated greatly by the cowling when on. That fan noise then is completely undetectable at anything above 3kts motor speed due to the other factors coming into play. Given that, it'd be a great waste of money for me to find a solution that eliminates the fan. And while fans can indeed be loud (e.g. little high speed power muffin fans as on my Vicor Megapac charger), larger, lower speed fans are not.
Anyway, I just want to put that out there. For an audio clip (lousy phone audio) of my motor in action, here's a link:
You can at least detect that with speed it's speed-dependent noise you hear and not the fan.
YMMV-
-Myles Twete, Portland
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com]
Sent: Tuesday, May 27, 2014 9:40 PM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Electric or air cooling for outboard question?
I will be looking at that Yahzdi, trying several solutions. I have a stethoscope for noises, but it doesn't seem to isolate the area enough. I loosened the shaft to motor coupling and that might help, also got a buddy looking at different motor mounts, and third I'm thinking about changing to a rubber tube over the drive shaft, and shifter rod, while I have it out. I don't have the water cooling hooked up yet either. My motor guy says the upper bearing is fine, that was a worry as they can howl a lot, as can the water pump I think.
I will be curious as to how yours works out, hopefully you will have better results. What size outboard are you putting the motor on ? Mine is on a Evinrude 50 hp, and the new one will be on a Suzuki 6 hp – but a lot more prop, and lower max throttle settings. I plan on Deka AGM batteries, so those are a given when finished – I like those better than lithium at this time.
Good luck, Cal
F
Sent: Tuesday, May 27, 2014 8:44 AM
Subject: Re: [Electric Boats] Electric or air cooling foroutboard question?
Thanks for the response Cal. Do you know which part of the project the noise is coming from? Is it motor or cooling or ???
Thanks
To affect the quality of the day, that is the highest of arts. Thoreau On 05/26/2014 08:43 PM, 'cal' h20dragon@centurytel.net [electricboats] wrote:
Exactly what I am doing now, good luck with that. Mine works good, except for excessive noise that we are still working on. Best of Luck, Cal
Sent: Sunday, May 25, 2014 12:01 AM
Subject: [Electric Boats] Electric or air cooling foroutboard question?
Hello to all,
This is my first posting, so here is a little about the project. I am
Yahzdi Taillon. My friend Ken Tate and I have acquired a 26' Columbia
River Scow of unknown origin.
To power it we are converting a 40HP Suzuki outboard to electric power.
The general plan for now is to use a 48VDC 10KW Golden Motor liquid
cooled brushless DC motor and their matching sine wave controller. First
let me state I am new to electrification of any vehicle, so most of my
decisions have been based on what sounds cool (pun intended). I have
done a lot of homework but the liquid cooling decision has little real
knowledge behind it. I have decided that I want the motor reversing
function to be electric motor reversing and not outboard gear box
reversing. So using the outboard's water pump is not an option.
That is my question to the group. What are your personal views and why?
My first reason for liquid cooling was to avoid motor cooling fan noise.
I decided I would pump raw water (sea water because we are in
Bellingham) through the motor and a fabricated aluminum water cooling
plate for the controller. Ken works for an aluminum boat building
company so we get the benefits of very reasonable CAD designed and cut
aluminum fabrication.
It didn't take long to see possible flaws in that scheme. Pumping sea
water through a motor that is probably made of aluminum and probably has
relatively small waterways might not be very clever. So I am now looking
at a closed loop for the motor with a pump to circulate the coolant
through the motor and one side of a fabricated aluminum heat exchanger,
and a separate pump with strainer to circulate raw water through the
other side of the heat exchanger. The heat exchanger would do double
duty as the controller heat sink.
Ken has suggested the possibility of using a radiator with a fan.
Plausible I think, but I just re-introduced fan noise.
This is getting quite complicated and costly just to avoid fan noise. At
this stage of the motor conversion project, all we actually have on hand
is the Suzuki outboard that works fine except for the very dead power
head, and 12 12V 139AH AGM batteries. So we are still in a position to
change our plan.
I understand the problem being solved is getting rid of the heat the
motor generates when being used. I have no real experience with how much
heat there is or how challenging it is to get rid of.
Thanks in advance for your input.
Regards,
Yahzdi
--
To affect the quality of the day, that is the highest of arts. Thoreau
--
To affect the quality of the day, that is the highest of arts. Thoreau
Posted by: "Myles Twete" <matwete@comcast.net>
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