Carter:
I'm with you on going with technologies that have been proven. That's why I went with AGM batteries for my system though I could see the benefits of Lith batteries I could not justify the cost for my system and needs. I also imagine I might heading down the intercoastal waterway someday and have a battery go bad. I wanted to be able to get a replacement from a local distributor the next day. That was my thinking at the time anyway. I still keep up my interest in following new advances but, like you I like to see a track record of at least five years. Though some are more disposed to be early adopters. I say God bless em. Somebody has to make the leap. I felt that way five years ago when I began to consider electric propulsion for my boat. There were not many people selling EP systems and I did actually know of any boats at had done it. So it was a little bit of a leap of faith to lay out the money. One of the things that made me go with the ASMO MARINE system was that the major components were avaliable from other sources off the shelf. Also the system was engineered to meet ABYC specs. When I called my boat insurance company five years ago to let them know what I was going to do. Their response was "YOU"RE GOING TO DO WHAT?" Then I knew that there was not a lot boats that had done this and I did not want to give them any reason for them to drop my boats insurance coverage. Even though I felt I was an early adopter there are many others here who have been involved in using electric propulsion systems on boats way before I considered it for my boat. People like Myles and others. I learned a lot both before and after I installed my system from them and still continue to learn here. I agree with you about the brushed DC motor not being that much of a maintenance issue compared to some of the newer motor technologies. The brushes on my Lynch motor are suggested to be replaced every 3,000 hours. My diesel engine died after twenty years at 1,900 hours. Nuff said!
Capt. Mike
From: Carter Quillen <twowheelinguy@yahoo.com>
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Saturday, November 19, 2011 9:44 PM
Subject: Re: [Electric Boats] 10 KW + motor technology
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Sent: Saturday, November 19, 2011 9:44 PM
Subject: Re: [Electric Boats] 10 KW + motor technology
Thank you for sharing your reasoning with us. Your answers have raised a couple more questions for me though:
What is IP 54 protection? I'm guessing some kind of current limiting technology to protect against overheating maybe? I've heard that's a new thing on some motors.
You mentioned being constantly on the lookout for new technologies, is there something wrong with some of the old technologies? I am always a little leary of new technology myself and tend more towards stuff that has a track record of long term success. Besides the inconvienience of changing brushes every couple thousand hours or so and maybe a few less efficiency points, do brushless motors offer any other advantages over brushed motors. I mean is there really that much difference between 91% and 94% efficiencies? I know the brushless motors are lighter and the motorcycle guys love that but weight isn't that big a deal on a boat. My experience with other types of electric motors has always been that the ones that weigh more usually perform better in the long run but admittedly, this is not universal. Do the brushless motors last longer or are they more durable in some other way?
What are the advantages of having a permanent magnet?
Are any of these motors more corrosion resistant in some way?
I looked at your website, very nice btw, but all the pictures I saw of past installations looked like E-tec or Mars frames. Does Perm make a motor that looks like that or did you use to use E-tec motors? All the Perm motors I've seen have had the bigger diameter to length ratio but I'm sure I havn't seen them all.
Thank you again for your helpful insight. I had been thinking about developing a water cooling system and you have convinced me to make the extra effort.
Carter
From: James <james@toolboat.com>
To: electricboats@yahoogroups.com
Sent: Saturday, November 19, 2011 5:38 PM
Subject: [Electric Boats] 10 KW + motor technology
Carter,
This new thread is in response to an inquiry on why we chose the Perm Motor for our 10 KW motor.
Choosing a motor is a bit of a moving target with new technologies coming online all the time. However there are very few motors that offer what the Perm does already in the 10 plus Kilowatt range. If there are other motors out there, I would be happy to hear if they can match my core criteria for a motor for a 20,000 lb boat up to 40 feet long :
- water cooling
- 94% efficiency
- up to 23 KW at 96 volts with torque up to 54 Newton Meters with peak torque up to 80 newton meters.
- double stator, brushless permanent magnet
- can be custom wound for a particular application. Ours was for 2000 rpm, 48 or 72 volts at 10 KW
- weight of 31 kg
- IP 54 protection
Its water cooled and hooking into the largest heat sink in the world ( the ocean ) just seems to be a good idea to me.
The people at Perm have been very clear as to what they can provide and participate in the design process. At this time our Perm Motor 10 KW is somewhat of a custom solution for individual clients. I have one in stock right now configured for 72 volts, which I think is a good idea once you get up to the 10 KW level. This means that all cables have to be shielded and you need ground fault monitoring to be ABYC compliant, which may be necessary for some insurance companies.
I spent some time in Germany with Perm Motors and met their engineers. What is most important to me is efficiency and having the majority of the energy go into the propeller rather than up in heat.
Efficiency is also relative to rpm, and they provide a map of that curve.
By being able to water cool the motor, you don't get thermal runaway. At 10 KW, bigger is better.
This motor will also form the basis of our larger motors to come in the 20 KW range. They will be run on 96 volts.
Perm also shares my view of conservatively rating products on a continuous basis at a specific operating temperature.
All of our motors are rated to be capable of crossing oceans, and for a bigger, heavier electric boat, this motor I believe makes the most sense at this time.
James
www.propulsionmarine.com
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To: electricboats@yahoogroups.com
Sent: Saturday, November 19, 2011 5:38 PM
Subject: [Electric Boats] 10 KW + motor technology
Carter,
This new thread is in response to an inquiry on why we chose the Perm Motor for our 10 KW motor.
Choosing a motor is a bit of a moving target with new technologies coming online all the time. However there are very few motors that offer what the Perm does already in the 10 plus Kilowatt range. If there are other motors out there, I would be happy to hear if they can match my core criteria for a motor for a 20,000 lb boat up to 40 feet long :
- water cooling
- 94% efficiency
- up to 23 KW at 96 volts with torque up to 54 Newton Meters with peak torque up to 80 newton meters.
- double stator, brushless permanent magnet
- can be custom wound for a particular application. Ours was for 2000 rpm, 48 or 72 volts at 10 KW
- weight of 31 kg
- IP 54 protection
Its water cooled and hooking into the largest heat sink in the world ( the ocean ) just seems to be a good idea to me.
The people at Perm have been very clear as to what they can provide and participate in the design process. At this time our Perm Motor 10 KW is somewhat of a custom solution for individual clients. I have one in stock right now configured for 72 volts, which I think is a good idea once you get up to the 10 KW level. This means that all cables have to be shielded and you need ground fault monitoring to be ABYC compliant, which may be necessary for some insurance companies.
I spent some time in Germany with Perm Motors and met their engineers. What is most important to me is efficiency and having the majority of the energy go into the propeller rather than up in heat.
Efficiency is also relative to rpm, and they provide a map of that curve.
By being able to water cool the motor, you don't get thermal runaway. At 10 KW, bigger is better.
This motor will also form the basis of our larger motors to come in the 20 KW range. They will be run on 96 volts.
Perm also shares my view of conservatively rating products on a continuous basis at a specific operating temperature.
All of our motors are rated to be capable of crossing oceans, and for a bigger, heavier electric boat, this motor I believe makes the most sense at this time.
James
www.propulsionmarine.com
------------------------------------
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