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Old 27-07-2008, 03:37   #16
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The real issue will be the incredible cost to manufacture a keel in the shape of a Lithium Ion battery , the battery,s as standard products are already expensive , around 1000 $ per Kw usable power now imagine making these small cells into a keel sized shape I is my guess that would triple or even quadrouple the cost to $ 4000 per Kw x 20 to 30 Kw
or $ 100.000,00 for a lithium Ion keel that needs replacement evey 6 to 10 years ?
Having a normal keel or daggerboard and make space at the lowest and nearest point to the centre of gravity seems more logical.

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Old 27-07-2008, 08:50   #17
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Yes, the expense would be great. But if there were standard sized battery modules for this purpose, you could design a keel with a hollow core and put as many batteries in as would fit.
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Old 27-07-2008, 09:49   #18
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Yes, the expense would be great. But if there were standard sized battery modules for this purpose, you could design a keel with a hollow core and put as many batteries in as would fit.
Hollowing out a keel is not complex or expensive since you build it that way in the beginning. You have now successfully solved the most trivial aspect of the problem.

The concept that you can beat the general cost as Gideon notes of $1,000 / kw is independent of how you store the batteries. Just because you might choose "standard" modules you still at at where the numbers begin now. All batteries these days are indeed standard modules. Perhaps if we had magic batteries it would be cheaper. If we could have magic batteries I'm in favor of smaller ones that don't need to be stored inside the keel. Once a keel is bolted on it's really meant to stay there. Removable keels serve no real purpose.

There are no large scale applications using Lithium Ion batteries other than the mass of them produced for laptop computers. Silver halide is even better but suited for applications using far less power than a laptop. Some technologies only work for small power production and some will store a large amount of power storage.

The basic lead acid battery is still the only suitable technology for mass storage of power yet the subtleties of the many types have changed a little bit over the years with new tiny changes to come at best. This technology is easily 70 years old so it's not like the dumb stuff has not been figured out.

What needs to change is the ability to recharge batteries relative to the time required drain them. They already make 2000 lb forklift batteries delivered to your loading dock with a phone call. They run all day and charge all night for days on end. On a boat they would run all day (maybe a couple days) and charge all week if not 2 weeks. The forklift application works because the forklift operates in a very predictable way and you can run it every day during a normal working shift because it can recharge all rest of the time plugged into an AC power source that is infinite. All requirements are met. They still are not cheap batteries though they work.

The giant battery becomes a curse on a boat since you need to recharge them fully to keep them in good condition. Lead acid batteries don't like to be fully depleted or they also lose longevity as well. At 50% usable capacity you get the best return on investment. This is how they may last 7 years.
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Old 27-07-2008, 13:32   #19
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Paul has some excellent points on this subject. Some other major points to consider is going to be getting the "module" in and out of the keel every so many years. That is either going to mean radical cabin hacking or a purpose designed cabin to gain access. another issue is going to be cost every so many years of a bank. I doubt many will be able to afford it. Even the high cost of diesel now....in fact even if Diesel went to $10/ltr, I doubt you would use enough fuel to make battery power more economic. The over all cost and on going costs are way in excess of the amount of Diesel you are going to use over the same time.
And finally, even though in theory it is possible to get 10yrs or more out of the best batteries, in reality in high demand situations like propulsion, it doesn't happen. Look at the forktruck, golfcart and other similar machines out there. I have been in an industry where we used elecric and LPG powered Forktrucks and we got 12mnths on average for the battery banks before having to change them out. And they were Trojan batteries too. Remember that a battery does not work at a 100% performance level over it's life. It's ability to recharge fully and deliver it's total grunt over time gets worse and worse to the point where you have to change out.
Then the final point is the efficiency. If you can charge with wind and solar, then that's kinda free to a point. The light and the wind maybe free, but there is a cost still . Water towed generation comes at an even greater cost to your speed.
There is a lot to consider and as of yet, the cheapest form of propulsion is a Diesel engine. OK, maybe sail, but if you factor in new sails and rigging every 10yrs, it ain't that cheap either.
The other issue is the way propulsion systems get used, the chances of having any
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Old 27-07-2008, 14:28   #20
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. But how would an outboard fair in conditions so bad that you aren't able to sail?
They are worthless.
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Old 27-07-2008, 15:30   #21
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There is some rather interesting work being done with ROV battery systems utilising magnesium/oxygen cells capable of production @ 1.6 volts per cell (only marginally lower than the current 1.8 volt/cell capacities with hydrides). These systems look promising for the obvious weight savings due to usage of seawater as you electrolyte (therefore no need for electrolyte storage since it's always available). This seems the most promising of the approachs I've seen to date....

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Old 27-07-2008, 16:46   #22
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I understand that there are technical challenges. Battery/hybrid technology WILL improve. Hybrid automobiles are just now coming into large scale production. This technology will eventually be applied to sailboats, I'm sure of it.
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Old 27-07-2008, 18:40   #23
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Lead acid batteries are clearly the technology of choice for a sailboat, even assuming lion and other technologies become viable for high energy uses such as the current crop of electric sports cars able to achieve speeds well upwards of 100 mph. The problem, as Paul points out, is primarily one of recharge.

There are many methods of for generating electricity afloat, but few can even theoretically generate enough electricity to recharge a monolithic keel battery within a 24 hour period, other than a generator. And the cost to run the generator would outweigh the benefit of using electric drive since for less initial expense and less total embedded energy you could install a diesel drive.

So the net result is at this stage of development it appears electric drives are not economically better than running a diesel systems. Where a sailboat is primarily operated without auxiliary propulsion it is possible, though not very reasonable, to run the boat using exclusively non-fossil fueled electrical power.
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Old 27-07-2008, 19:00   #24
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I was discussing this last winter with a boat builder friend of mine, who had looked at the currently available commercial electric propulsion systems. We figured it would be cheaper to buy a new Prius, throw away the body, and put the propulsion system into the boat. OK, yes I know it's not diesel, nor marinized, but the basic concept - a marinized Prius propulsion system, converted to diesel - would be great.
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Old 30-07-2008, 04:56   #25
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Hankthelank

you may wish to look here DE-Whisperprop

FischerPanda has something like "electric outboard",
looking seaworthy and called Aziprop Aziprop

but don't even dream about "100% green" - you will for sure need a powerful
generator to drive your motor; no sun/wind/water chargers may keep your batteries
(if big enough to feed the main drive) charged.

The best batteries to use with electric drive would be not Lithium, but NiMH
(like Nilar, Saft or Cobasys* ), having standart 12 or 24 V voltage and great tolerance
to charge currents & lifecycles/DoD rate
Only these companies are not interested in dealing with small(er) clients
================================================== ========
*rumour says this company is a NiMH battery killer, not developer; anyhow, their
Series 9500 battery hass excellent specification, at least on paper
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Old 30-07-2008, 06:04   #26
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Contrary to general beliefs that the Lithium Ion battery would not be suitable for propulsion
a couple of car manufacturers have ordered large quantity's of these battery's for the main power source of their new developed Electric and Hybrid electric cars.
We have been using Lithium Ion Phosphate battery,s for well over 2 years and so far besides the high expense they function perfect.
Out of a 18.6 kilo 12.8 volt battery we get 1.7 Kw usable power and we use 11 in series for a voltage of 140 volts DC.
Max continues discharge on these units is 150 Amps and we stay well below that with our Green Motion retractable propulsion system.
So far these have only been tests and the first cat to be launched in fall this year will only have the Lithium units on board.

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Old 30-07-2008, 06:19   #27
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Quote:
Originally Posted by vacendak View Post
Hankthelank

but don't even dream about "100% green" - you will for sure need a powerful
generator to drive your motor; no sun/wind/water chargers may keep your batteries
(if big enough to feed the main drive) charged.
Hallo Hank

I thought we where discussing sailing boats and these are in general Green , the wind is our propulsion system and only when going into a harbor or out a harbor we need a different type of propulsion system.
That system can be fossil fuel powered but electric power is coming ahead at a fast pace
Diesel generators will supply a backup for that occasional period where for a longer time propulsion other than sail is needed but it is already possible to minimize the use of fossil fuels if the mindset allows it.
That also means that when sailing at speeds of 4 knots motors are not started.
It is our aim to perfect the Green Motion system in such a way that the efficiency will provide 3 hours of running time without having to start a diesel generator.
By the end of this year we will know if we have achieved this target.
If that is the case the use of fossil fuels will be minimized to 5 % of its present levels , at least on our yachts.
It is still a costly way to go but only if one does not take pollution and the cost of fuel into account.
I would like to get some insight in to how much fuel the average sailors use each year .
Only then with the knowledge of this amount of fuel will we know that actual difference in cost.
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Old 30-07-2008, 07:14   #28
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only when going into a harbor or out a harbor we need a different type of propulsion system
IMHO not only, sometimes it is calm, also for extended periods
(my personal log reminds of 48+ hours of wind between 0 and 2 knots
in 2006 near Montenegro coast)
in such case extended motoring might be of use
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Old 30-07-2008, 07:18   #29
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You are right off course , I once had to motor all the way from the Azores to the gulf of Biscay since there was no wind for 7 days in a row.
Specifically for these circumstances we build in a Generator but in general one can keep the use of fossil fuels very limited.
Off course with speeds below 4 knots motoring is a must.

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Old 30-07-2008, 07:31   #30
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What is the diesel fuel usage with a diesel engine running a generator, which supplies juice to an electric motor that turns the prop, vs. a system where the diesel engine turns the prop directly when there isn't enough juice for the electric motor or more power is needed?

In a true hybrid system you would need some sort of clutch to switch between the two engines.
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