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Old 05-10-2012, 16:22   #1
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Battery consumption

Is it possible to run my boats electronics solely on wind generators and solar panels? I have a fridge, freezer, hydraulic autopilot, standard gps and radar, VHF radio, and all the standard lighys

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Old 05-10-2012, 16:34   #2
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Re: Battery consumption

Yes, if you have enough solar panels and wind generators.

The water is always bluer on the other side of the ocean.
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Old 05-10-2012, 16:35   #3
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Re: Battery consumption

What is your average generating capacity and what is your average usage? Some days you may not have enough wind for the wind generators, and at night you will not have much coming from your solar panels. There may also be days when solar is not putting out too much due to clouds, rain, less than optimum angle to the sun, etc. So figure what your peak usage is and compare that to your average generating capacity. If you usually have a surplus or at least break even, all well and fine, but if you have a deficit, you may need to turn off as much unnecessary equipment as you can.
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Old 05-10-2012, 16:38   #4
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Re: Battery consumption

That's a very broad question, there are lots of threads full of information along those lines here on CF.

The short answer is "yes". Also "no". Have to have a lot more detail on electrical usage and available space for solar and wind installation. On our boat we get >90% from solar and wind, and use the alternator on the auxiliary for those rare occasions when Mother Nature is not sufficient. Don't have a generator.

But it really does depend on how much energy things like your fridge/freezer eat, how much room you have to install panels, and where you will be using your boat.
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Old 05-10-2012, 16:44   #5
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Re: Battery consumption


just make a list of every item that you will be using regularly, write down how many amps per day the item will consume, and you'll have a rough aproximation of how many amps you'll need per day. there's your target.

how to get those amps is the other part of the equation. and you can't just add up the total output of all your solar panels and windgens. solar works best on long cloudless days. windgens work best in steady breezes -usually 10 to 15 knots or more. but you can't always count on ideal conditions.

so you'll need a large battery bank to store up energy for days (and nights) when you're getting less than optimal battery charging.

and you'll want to work both sides of the equation. for instance, led lighting to reduce power needs, an mppt controller to give you a little better bump when solar charging.

a big subject and well covered on this forum. searching it will give you boatloads of information that may take days or weeks to digest.

and don't forget that, when all else fails, you can run your engine or your honda generator to bring the bank up when mother nature is not being kind to you....
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Old 05-10-2012, 17:50   #6
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Re: Battery consumption

The short answer is Yes - we do it with just solar, no wind turbine.

OneStep has the right idea & good info. To take it a step further, we had our son do a complete Energy Budget, which you can see online. Take all your energy consumers (VHF, fridge, pumps, etc) & measure how much current they draw (do it accurately). Multiply that by how long they're on in a given day. A spreadsheet really helps here. At the end of this you'll have your amp-hour (or amp-minute) consumption for a day.

From the above exercise we found that if you divide the wattage rating of your solar panels by 3, that will give you amp-hours into your battery on a sunny day in the tropics. So, we have 480W (nominal) of solar panels, & they give us ~160Ah into the battery (our MPPT controller boosts that). Higher latitudes will give you more in the summer but less in the winter.

It's a good idea to have enough battery capacity to never cycle the batteries too low - keep them in the top 20% & they'll last much longer. You'll also want capacity to keep you powered through a series of cloudy/windless days. We have 660Ah of deep cycle batteries.

Converting to LED lighting & other power reduction techniques (like better insulation on the fridge/freezer) will also help a lot. We converted our G4 Halogen bulbs to (brighter & warmer) LEDs for $4 each at Lighting Matrix. Now we don't really care if we leave the lights on.
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Old 05-10-2012, 17:57   #7
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Re: Battery consumption

First, consider your total electrical demand. Actually calculate it, don't guess. Second, consider that you might need something more in the future, it happens, so plan for it. Third, at a minimum, double that number and use it as your MINIMUM battery capacity. Fourth, install a battery bank sufficient to supply that DOUBLE of demand. Then, provide a supply of electricity that will, AT A MINIMUM, meet that electrical demand and storage. Be rational and realistic, otherwise you are merely deluding yourself and wasting money and time.
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Old 05-10-2012, 19:08   #8
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Re: Battery consumption

We had solar, and a water turned genarator attached to our prop shaft, the solar was only 100 watts or how ever ya rate them, but the shaft turned gen kept our 2 battery banks full when we were sailing ! never had to start the engine at sea! total cost for the set up was about 300 1980 dollars. If ya sail a lot ya might think about a system like this ! Im in the process of trying to fit this type of system aboard our new to us ketch! It has a Gen set but I would rather save that for when we need Ac LOL much cheaper to supply power from the motion of the ocean !! LOL

Bob and Connie
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