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Old 12-09-2011, 11:28   #16
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Having multiple battery banks allows one set to charge with on system, while drawing from another.

The best format is to have 3 or more battery banks, which allows switching for use, charging and service.

As for the connecting aspect. By connecting batteries in series you increase the voltage and parallel you increase the amperage. For a higher voltage motor, you would run them in series and then connect the series banks into parallel for the amperage increase.

This allows for the use of a higher torque engine and lower draw on the battery banks.
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Old 12-09-2011, 11:43   #17
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Re: Solar-Powered Engines ?

Quote:
Having multiple battery banks allows one set to charge with on system, while drawing from another.
Sorry, but that is the least efficient method of battery use. At their very best the battery charge/discharge cycle is 90% efficient. More generally the round trip is 80-85% efficient. For every 100 units of charge you put into a battery you get back only about 85 units. Far more efficient to utilize the energy directly if you can. Batteries should only be used when you can collect the energy now, but want to use it later. If you are collecting and using the energy at the same time then it should not be making a trip through the batteries.

For the OP's question - check out Educational Tall Ship. They are proposing an electric auxiliary system that will scavenge charging power from the rotating prop while under sail. It will slow the boat down under sail, but will charge the batteries for maneuvering with the motors later. Not sailing yet, so we'll see how realistic it gets to be.
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Old 12-09-2011, 11:52   #18
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Re: Solar-Powered Engines ?

Quote:
Originally Posted by PushingThePen View Post
Having multiple battery banks allows one set to charge with on system, while drawing from another.

The best format is to have 3 or more battery banks, which allows switching for use, charging and service.

As for the connecting aspect. By connecting batteries in series you increase the voltage and parallel you increase the amperage. For a higher voltage motor, you would run them in series and then connect the series banks into parallel for the amperage increase.

This allows for the use of a higher torque engine and lower draw on the battery banks.
However, none of this addresses the problem of extremely limited range without using a fossil fuel powered generator. Batteries and alternative charging systems available today, no matter how they're connected, will not give you a range of a 300-400 nautical miles at cruising speed.

So far all the systems I have looked at have enough power to get you from the dock to the ocean, then you are sailing with a chance to motor a few miles occasionally.
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Old 19-09-2011, 00:44   #19
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Originally Posted by skipmac

However, none of this addresses the problem of extremely limited range without using a fossil fuel powered generator. Batteries and alternative charging systems available today, no matter how they're connected, will not give you a range of a 300-400 nautical miles at cruising speed.

So far all the systems I have looked at have enough power to get you from the dock to the ocean, then you are sailing with a chance to motor a few miles occasionally.
Too true. Someday.

There are some amazing breakthroughs that people really don't know about, or think are to expensive. Most don't even realize that a solar panel has a 25 year warranty. Or what the differences are to the main 3 types of panels.

There is always something better, but the reality is that it has to start somewhere to make a true shift in thinking. I'm looking to have an entire boat coated with thin film solar and see where that will lead. And yes, it will be feeding batteries.

Integrate that with wind turbines and I should have enough power to push her at around 7-10 knots continually for several hours with out an issue. This will be without completely draining the batteries.

Even thought about using modified capacitors instead of traditional batteries.
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Old 19-09-2011, 05:44   #20
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Re: Solar-Powered Engines ?

so you get a solar array at 14 to 20% efficiency and spend a lot on it.
Then the nantenna solar cells come along at 95% efficiency and a lot cheaper.

Nantenna to Improve Solar Capture Threefold - Domestic Fuel

I just refuse to be an adopter of current solar tech as it is too expensive and inefficient for the money spent.
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Old 19-09-2011, 06:29   #21
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Re: Solar-Powered Engines ?

Pure electric power is just not practical for two reasons, Cost and Weight.

The amount of money required to make a decent solar/wind powered electric boat would be enough to buy fuel for many years of cruising without the hassle, also, dont forget that batteries don't last forever so in five years or so, there's another big bill to renue them.

The most practical way of harnising electricity is to go the hybrid route like many car manufactures have done. Lagoon already have a hybrid on the market,

Lagoon 420: First Production Hybrid | Cruising World
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Old 19-09-2011, 06:46   #22
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Re: Solar-Powered Engines ?

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so you get a solar array at 14 to 20% efficiency and spend a lot on it.
Then the nantenna solar cells come along at 95% efficiency and a lot cheaper.

Nantenna to Improve Solar Capture Threefold - Domestic Fuel

I just refuse to be an adopter of current solar tech as it is too expensive and inefficient for the money spent.
I am also waiting on solar before I invest as there seems to be a lot of research and new technology being discussed. Unfortunately none of it seems to be in production, yet.
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Old 19-09-2011, 06:46   #23
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Re: Solar-Powered Engines ?

Then again what about when there's no sun. I am in Costa Rica right now with days of over cast, and no wind. If it wasn't for burning some diesel I would be out of juice, and this is just sitting. No way to raise an anchor, or power out of here to the bay. For now it's cost effective to have wind, solar, Honda 2k, and deisel to produce electricity........i2f
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Old 19-09-2011, 08:15   #24
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Re: Solar-Powered Engines ?

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Originally Posted by PushingThePen View Post
Having multiple battery banks allows one set to charge with on system, while drawing from another.
There is absolutely no reason why you cannot be drawing from a battery bank at the same time that you are charging it. When done that way, depending on how much you are drawing and how much you are charging, you will actually be drawing from the charging source, or the batteries and the charging source both.

A single, larger house bank is more efficient, overall, than multiple smaller banks of batteries.
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Old 19-09-2011, 09:30   #25
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Re: Solar-Powered Engines ?

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so you get a solar array at 14 to 20% efficiency and spend a lot on it.
Then the nantenna solar cells come along at 95% efficiency and a lot cheaper.

Nantenna to Improve Solar Capture Threefold - Domestic Fuel

I just refuse to be an adopter of current solar tech as it is too expensive and inefficient for the money spent.
It is a long shot. I bet the black silicone will be the first breakthrough.

The problem is not to gather more: there is only so and so amt of energy per sq ft. The problem is to find material that will convert a larger percentage of the energy. It is a material challenge, not a design challenge.

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Old 19-09-2011, 09:39   #26
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Re: Solar-Powered Engines ?

BTW I have read on gizmodo that works towards a capacitor-style battery are very advanced. Who knows, maybe this is the thing we are all waiting for?

b.
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Old 19-09-2011, 09:50   #27
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Re: Solar-Powered Engines ?

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It is a long shot. I bet the black silicone will be the first breakthrough.
The problem is not to gather more: there is only so and so amt of energy per sq ft. The problem is to find material that will convert a larger percentage of the energy. It is a material challenge, not a design challenge.
b.
Exactly.
Solar Irradiance or Insolation are the measure of solar radiation energy received on a given surface area in a given time - the amount of energy available.
Mean solar power above the Earth’s atmosphere is about 1366 Watts per Square Metre (Wm−2), but sunlight is attenuated on its way through the atmosphere, so the insolation has fallen to about 1000 Wm−2 by the time the light has reached the Earth’s surface. The electrical power produced by a panel when it is illuminated by 1 kWm−2 of solar radiation is called the “peak output power” of the panel. Since current solar panels are only around 15% efficient, that works out to approximately 150 watts per square meter in direct full sunlight.
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Old 19-09-2011, 09:51   #28
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Re: Solar-Powered Engines ?

Something to think about, even in the dreaming world, is the amount of space required for solar power. The sun (nominally) delivers about 1000 W/m2 to the Earth's surface. That value very occasionally goes higher (like 1200-1300), but very frequently is lower (like at night). So, if you have a 40 foot boat, say with a 13 foot beam, and rectangular you might be able to get 12x4 = 48 square meters = 48kW of solar power off an array mounted on the vessel (at 100% conversion efficiency). That assumes that whatever capture device you have is pointed directly at the sun, if it is not then the energy density drops, no matter what capture device you are using.

So, in a perfect world the best you could ever hope for would be about a 60hp motor on a 40 foot vessel. That's more than sufficient in the sailing world as an auxiliary (but remember, you can't really put up sails because you don't want to shade your capture device), but probably not sufficient in a power only vessel.

Guess we all have to go to multihulls to get the deck space needed Not saying it can't be done, or that there can't be changes to naval architecture. But the amount of effort required to move through the water isn't going to change, nor is the amount of solar energy delivered at the surface, so those are the limits you have to work within, and IMO it doesn't look promising for a solely solar powered vessel within the real world constraints.
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Old 19-09-2011, 09:54   #29
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Re: Solar-Powered Engines ?

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BTW I have read on gizmodo that works towards a capacitor-style battery are very advanced. Who knows, maybe this is the thing we are all waiting for?
b.
It's called a "Supercapacitor" (or ultracapacitor or double-layer capacitor)
But:
"... The specific energy of the supercapacitor is low and ranges from 1 to 30Wh/kg. Although high compared to a regular capacitor, 30Wh/kg is one-fifth that of a consumer Li-ion battery...
... the voltage of the supercapacitor decreases on a linear scale from full to zero voltage. This reduces the usable power spectrum and much of the stored energy is left behind..."
Supercapacitor Information
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Old 19-09-2011, 09:56   #30
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Re: Solar-Powered Engines ?

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Having a bit of experience with alternative energy systems, it is very possible to convert a boat to electric, since there are other charging sources besides just photovoltaic (solar).

One major boost is the small, high output, wind turbines. These are light weight, easy to mount and can be integrated to alternative energy systems.
.....
.
You seem to have access to data that the rest of us are missing. Could you please give a link or other reference to the above mentioned "small, high output wind turbines" ?

Cheers,

Jim
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