Diesel/Electric Propulsion System Design - Have your say!

[brian eiland]

Originally Posted by CatBuilder

Michael. I do appreciate your input greatly on this thread, but I have to ask if you read and understood my last post. I ask because the post I am quoting from you makes zero sense when related to the topic at hand.

That is why the electric based drive system is more economical than the standard setup when you are looking at an empty hull.

Geez. I am beginning to wonder if this thread was a bad idea. Some posters aren't even understand the concept of the system.

I had a chance to look back thru this subject thread, albeit quickly. CatBuilder I can understand some of your frustration with some of the replies, but I think you should expect some of this on an open forum. Besides you've ask some goodly number of questions related to diesel-electric powering, and it appears as though this is still a 'very young' technology for the yachting field, and as such there are many different opinions as to when and how to make use of it. So you should expect a lot of diverse opinions, but there is something to learn in many. I see a number of them with links to various related technologies, and welcome that. My electrically-challenged brain could learn something new, or at least reconsider some point made.

I was trying to follow all the development myself, including the hopeful use of rim-drive propulsions, but my 'electrically-challenged' brain was taxed to keep up. It appeared to me that Solomons Tech really started the ball rolling, but they were making use of a number of different products from various manufacturers, and they were experiencing some incapabilities with them in the final 'system'.

Along came Glacier Bay with a vertical integration of product, and I thought this was the one I would consider recommending as all the components were coming from the same manufacturer. So if problems arose during early deployment there was a single manufacturer to deal with rather than multiple ones each saying their individual product was not at fault, but likely it was some incompatibility with others. beside I had dealt with Glacier Bay on previous occasions with their excellent DC refrigeration equipment, including their attention to excellent cold plate equipments and superior insulation materials. My thought is they would product a top notch product (not cheap) that would be a std to reach. Alas I think the development monies they had available were just not quite enough, and then the faltering boat economy caught up with them. now it appears as though new management has moved in and 'profit motive' has resulting in them backing out of much of the development of their products.

Diesel-electric technology development has suffered as a result of this new world economy. The rim-drive technology development has suffered as well.

I assume you have seen this discussion and the links?
Electric drive motors for sail craft (mono & multi)
Diesel/Electric Propulsion for Sailboats

Nigel Calder did a really excellent series of articles on this new diesel-electric technology for yachts in the Professional Boatbuilder magazine. I think those can now be accessed by the public. He really fully covers the field.

...sorry have to go away right now (to be continued)

[brian eiland]

Originally Posted by Brian

....Nigel Calder did a really excellent series of articles on this new diesel-electric technology for yachts in the Professional Boatbuilder magazine. I think those can now be accessed by the public. He really fully covers the field.

Check the Nigel Calder articles in Professional Boatbuilder.

http://www.proboat.com/digital_issues.html

Page 74 Issue 112

Page 104 Issue 111

Page 140 Issue 109

Somewhere on one of my 3 computers I have all of these articles in a PDF format from which I made printed copies. I know I've read thru them on several occassions, and learn something interesting each time. In summary it appears as though the technology (and/or equip) was not quite developed enough for full-on powering applications...it just didn't compete remarkably with good old straight diesel power...yet. But I don't think that should condem its application in an 'aux to sailing' manner, nor where house loads could be significant

I also remained in contact with a gentleman who installed a Glaicer Bay system on his custom built cat from Chili. He ended up selling that vessel after bringing it back to the USA. He

[Jeremy Harris]

Originally Posted by masalai

Hi CatBuilder,
Again, charge management is VERY critical as they are usually hundreds of AA size cells in parallel and must be carefully managed internally... LiFePO4 I think is the most recent commercial iteration and several "new compounds" are in development now...

The comparative newness of this technology induced me to stay with the "Lead/Acid" technology in the 'safer' AGM packaging...

There are plenty of large format LiFePO4 cells around, have been for years. My own boat pack is made up from a big stack of 38120 cell (38mm dia, 120mm long) that are 10Ah each, and is now around three years old. There are much bigger format LiFePO4 cells around as well, with probably the 200Ah ones being around the best price point. The biggest LiFePo4 cells I've seen are the massive ones made for submarine propulsion; they are up in the many hundreds of Ah.

Oddly, I don't think I've seen any packs made up from tiny AA cells, other than the very cheap, low discharge rate, ones made in China for electric bicycles. These wouldn't be appropriate for high discharge use on a boat propulsion system like this though, even if they are still available (which I doubt).

[Injuneer]

Originally Posted by Jeremy Harris

Oddly, I don't think I've seen any packs made up from tiny AA cells, other than the very cheap, low discharge rate, ones made in China for electric bicycles. These wouldn't be appropriate for high discharge use on a boat propulsion system like this though, even if they are still available (which I doubt).

As a notable exception, the Tesla Roadster uses the 18650 Li-Ion cells that are just slightly larger than the AA format.

[Injuneer]

Originally Posted by brian eiland

I also remained in contact with a gentleman who installed a Glaicer Bay system on his custom built cat from Chili. He ended up selling that vessel after bringing it back to the USA. He

I believe I have read this guy's posts on CF ("gosstyla"?) some years ago. Quite an enemy of electric propulsion. I did some checking around at the time and found that his objections to the Glacier Bay propulsion system installed on his Alwoplast Crowther 47 were inconsistent and difficult to understand.

[CatBuilder]

I should probably mention that I'm not wiling to buy any pre-packaged marine systems.

I am only willing to use robust, off the shelf industrial systems. Those already have all the kinks worked out from years of use in industry.

Thanks for the input on the LiPO4 battery types and availability. Did you find large chargers for those batteries?

[Jeremy Harris]

Originally Posted by Injuneer

As a notable exception, the Tesla Roadster uses the 18650 Li-Ion cells that are just slightly larger than the AA format.

Yes, but these aren't LiFePO4 cells as being discussed here, they are the same chemistry as used in laptop batteries, LiCoO2 with extensive fire protection measures in place to mitigate the much greater risk of thermal runaway from this type of cell (when compared to LiFePO4, for example).

[Jeremy Harris]

Originally Posted by CatBuilder

I should probably mention that I'm not wiling to buy any pre-packaged marine systems.

I am only willing to use robust, off the shelf industrial systems. Those already have all the kinks worked out from years of use in industry.

Thanks for the input on the LiPO4 battery types and availability. Did you find large chargers for those batteries?

I ended up designing and building my own charger and charge control system, because I couldn't find anything off the shelf. This wasn't too easy, as all lithium chemistry batteries need cell-level monitoring, both during charge and discharge, for safety and longevity.

[Injuneer]

Originally Posted by Injuneer

As a notable exception, the Tesla Roadster uses the 18650 Li-Ion cells that are just slightly larger than the AA format.

Originally Posted by Jeremy Harris

Yes, but these aren't LiFePO4 cells as being discussed here, they are the same chemistry as used in laptop batteries, LiCoO2 with extensive fire protection measures in place to mitigate the much greater risk of thermal runaway from this type of cell (when compared to LiFePO4, for example).

Correct, that's why I pointedly identified the Tesla cells as "Li-Ion" (i.e., Lithium-ion Cobalt oxide), and not LiFePO4.

In many ways, large format LiFePO4 prismatics are ideal for use in a boat propulsion system. In a properly sized propulsion pack, the current draw should be reasonably bellow 1C. The smaller cylindrical 38120-type batteries such as the Headway have the advantage of allowing substantially higher current draw, but this is typically not necessary in a cruising boat application. The Headways do allow for a more granular cell monitoring, but at the expense of a more extensive (and expensive) BMS. Plus they typically require a special mounting rack with adequate allowances for cell spacing, as well as more involved wiring.

[Injuneer]

Originally Posted by CatBuilder

I should probably mention that I'm not wiling to buy any pre-packaged marine systems.

No worries, mate, given your requirements, there are very few pre-packaged marine propulsion systems of that flavor available. The only one I am aware of the African Cats system, but as you have already discovered, it is priced somewhat stratospherically.

[powerabout]

A mate of mine in the electric propulsion business who is building a new boat for himself, is tackling the marine side for the first time.
I'll let you know once it hits the water in a few months
Main aim to to get full use of main engine as gen set rather than solely propulsion

[Jeremy Harris]

Originally Posted by Injuneer

Correct, that's why I pointedly identified the Tesla cells as "Li-Ion" (i.e., Lithium-ion Cobalt oxide), and not LiFePO4.

In many ways, large format LiFePO4 prismatics are ideal for use in a boat propulsion system. In a properly sized propulsion pack, the current draw should be reasonably bellow 1C. The smaller cylindrical 38120-type batteries such as the Headway have the advantage of allowing substantially higher current draw, but this is typically not necessary in a cruising boat application. The Headways do allow for a more granular cell monitoring, but at the expense of a more extensive (and expensive) BMS. Plus they typically require a special mounting rack with adequate allowances for cell spacing, as well as more involved wiring.

LiFePO4 cells are also Li Ion, all the lithium chemistry secondary cells I'm aware of are Li Ion, in that they all work by ion exchange across a membrane, unlike other secondary battery chemistries that use chemical changes on the electrodes for energy storage.

Unfortunately, referring to a cell type as Li Ion doesn't really tell us much about the actual chemistry, it could be LiMnO2, LiCO2 or LiFePO4 or any one of the other lithium chemistries being developed.

[Injuneer]

Originally Posted by Jeremy Harris

LiFePO4 cells are also Li Ion, all the lithium chemistry secondary cells I'm aware of are Li Ion, in that they all work by ion exchange across a membrane, unlike other secondary battery chemistries that use chemical changes on the electrodes for energy storage.

Unfortunately, referring to a cell type as Li Ion doesn't really tell us much about the actual chemistry, it could be LiMnO2, LiCO2 or LiFePO4 or any one of the other lithium chemistries being developed.

Yes, naming conventions can cause communication and comprehension problems in several technical areas (generator vs. alternator vs. dynamo, etc.). But it has been my perception that when Li-Ion is used without any additional identification of the specific chemistry, most people seem to mean Lithium-ion Cobalt oxide (i.e., the kind that can catch on fire). Of course, that could be an incorrect perception.

Incidentally, what propulsion system do you have on your boat and how is it working out?

[Jeremy Harris]

Part of the mis-naming problem seems to stem from marketeers, keen to try and present safer Li Ion chemistries as something other than what they are, to get away from the connection with lithium batteries catching fire (which is remarkably rare, when you look at the many millions in use around the world). The problem is that now there are many other lithium ion chemistries in development, all of them Li Ion but most of them safer than the original LiCoO2 (but maybe not safer than some of the newer LiCoO2 cells!) the whole thing is getting to be a bit confusing.

My boat uses a low power electric drive, based on a much-modifed 2.8kW RC model outrunner motor from China, with a Headway battery pack, charged up all the time in use by a 200W solar panel array mounted on a canopy. The boat only has limited performance, its 18ft long and designed to cruise our inland waterways at the 4mph limit. These waterways rarely have any current to speak of, so the power requirement is pretty low.

[michael pierzga]

Dont know if anyone mentioned the popular Boatspeed Australia retractable drive unit. I see many on the gran prix race boats. looks simple to build. In spring I photo documented the servicing of one of these units. It Could easily be built by a Cat Builder type working in his "spare time"

http://www.boatspeed.com.au/pages/comp.shtml