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Old 11-14-2013, 08:52 PM   #21
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Pete

I follow where your generator produces 20kw of electricity per hour. The load demands on a boat are not that high in terms of refrigeration, nor the ability to charge the batteries. I had two 135 amp chargers going and residential refrigerator and a hot water heater and did not fully load my 8kw generator. Thus some part of the 20kw is not being used in the comparisons we have been making with panels. If I am correct you would need to run the generator more than 1.2 hrs per day in order to keep the refrigeration going.

Assuming you had my set up of two chargers producing on average 200 amps per hour recharge, you would need to run a generator for perhaps 2.5 hours over the course of the day. This is what I was doing when I had residential refrigeration.

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Old 11-15-2013, 12:00 AM   #22
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Hey Parmenter,

Get real! Nobody uses their yacht 365 days a year. 36 days a year would be more realistic.

Pete37
Sorry you don't get to use yours as often as you should.
Mine will be a full term live-aboard, only marina attachment will be for resupply (fuel, water, food, washing)
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Old 11-15-2013, 12:45 AM   #23
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There's a company on Vancouver Island that sells 5 - 100 watt panels for $500 Canadian. Plus you have to buy a controller.
Washer/dryer? Hair dryer? A 20 kW generator a big generator.
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Old 11-15-2013, 08:12 AM   #24
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...Get real! Nobody uses their yacht 365 days a year. 36 days a year would be more realistic.

Pete37
If you are planning on 36 days per year at anchor make no changes but your original post was about shore power independence.

We don't spend 365 days a year but over a 6 year period a minimum of 270 days a year at anchor with one year at 330 days for Hobo. Leave the states and you'd be surprised. Using Parameter's numbers, even at 50% of the time out, solar is a good deal.
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Old 11-15-2013, 08:35 AM   #25
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I am seriously looking at semi-flexible panels for the top of my bimini. I can easily get six - 100 watt panel up there. It would go a long way to reduce genset time. The current price is $199 for one 100 watt panel. I have seen the prices drop 25% in the last four months on semi flexible panels. So thats about $1500 for panels and controller. The attachment to the canvas is currently an unkown price for me. There are several companies who have done this for sail boats, so the methods for attachment have been figured out.
Semi Flexible 100 Watt Solar Panel 12V High Efficiency Sunpower | eBay
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Old 11-15-2013, 09:36 AM   #26
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We spent five months in Maine last summer on the hook. Never saw shore power. No solar. 110V Ice maker, 110V cheap dorm style fridge, all elec galley, 110V WH, lite like a Christmas tree every night, three kids and wife. Didn't move the boat much at all. Ran the genny long enough in the am to make coffee and breakfast and long enough in the pm to cook dinner. 1100AH battery bank 160A/MSW inverter/charger.

Just do it!
Daddyo I'm with you on this.

A good quality, properly sized generator gives our boats shore power independance.
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Old 11-15-2013, 10:18 AM   #27
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Pete says: "On page 232 we found Table 9-6 which describes the electrical needs of ďHighlifeĒ a 52í, eight year old, cutter rigged ketch. The table indicated that the daily DC demands were 115 Ah for House Loads, 75Ah for Activities, and 312 AH for AC loads supplied to the battery bank via an inverter. The peak load is 502 Ah. But not all of these loads occur at the same time so the average load from these three sources is about 301 Ah.
In addition one must add in the power for the refrigerator/freezer which running 24/7 at 12 amps burns about 280 Ah per day. It is the largest power consumer on the boat. The total and average for the day is now 581 Ah.
There are also the inverter loads which include the washer/dryer, hair dryer, toaster, coffee maker, microwave, vacuum cleaner and TV/DVD. They add up to 312 Ah but average out to about 187 Ah. The total and average for the day is now 768 Ah which at 12 volts is 9.22 kWh. This completes the compilation of DC loads.

But there are also AC loads powered by the generator and delivered directly to the loads at 120 volts. They include battery charging at 5 kWh, AC watermaker at 3.4 kWh and a small amount of air conditioning at 5.4 kWh (about enough to cool down the master stateroom so that you can sleep at night). The AC load total is 15.3 kWh.

The total, DC plus AC, load is 9.22 +15.3 = 24.5 kWh which requires 1.2 hours of generator operation at full load, burns about 1.9 gallons of fuel and costs $7.68 at $4.00/gallon."

I put these numbers into a spread sheet, and for the life of me, can't figure out how you came to your final numbers? I feel it is easier to use watts instead of Amps and/or AHs for calculating daily loads since watts work for DC and AC loads.

I come up with the same 581 AH/6,972 Watts/day as you. But then, I lose you. You have AC load of 5000 watts for battery charging and then add on the above 6,972 watts for DC loads? Essentially, the DC loads ARE what you are replacing in the battery, so if you add 10-15% for losses, your battery charging total should be 8KW?

Air conditioning takes about 7.5% in kW of it's BTU rating (my 8,000 BTU A/C draws about 600 watts when running). Your number of 5.4 kW for air conditioning would allow for 6 hours of 12,000 BTU - is this about right as per your usage?

Your allocation of 3,400 watts for water making - is this a daily average? How many gallons of water do you get for 3,400 watts?

Using your raw data numbers, I come up with: 8kW for batt charging (includs DC loads), 5.4kW A/C, 3.4kW water maker for a total of 16.8kW. Your one-hour plus of a 20kW seems about right.

Am I missing anything?

Since the goal is to be independent on for extended periods of time, living aboard at anchor, then most likely a combination of energy sources could be combined to work?

If, like you, you already have a generator of sufficient capacity, then nothing needs to be done. Just dinghy ashore to refill Jerry cans with diesel as necessary.

If, one is starting with a clean sheet of paper, then, depending on life-style goals and budget, other solutions may present themselves. A combination of:

1. Small Wind - a 1.5kW rated wind turbine (cost about $4.5k) will generate an average of 600 watts/hour or 14kW/day. This is an average based on east coast U.S. wind charts.
2. Solar - about 3kW of solar (cost of panels about $3k) will generate an average of 12kW/day.
3. Diesel generator - small is OK - maybe 4kW or so? On an auto-start/stop switch?
4. High-amp alternator(s) on main engine(s).
5. Big enough of a battery - to get through 24 hours - 20kW hours/1,666 AH at 12v. About $7k for Lithium, less for AGM. The bigger, the better to capture both solar and wind energy when it's plentiful.
6. More efficient fridge to save 2kW/day (new tech ones use 50 watts/hour)
7. More efficient LED lighting
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Old 11-15-2013, 10:24 AM   #28
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Solar Panels for Bimini

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Originally Posted by fryedaze View Post
I am seriously looking at semi-flexible panels for the top of my bimini. I can easily get six - 100 watt panel up there. It would go a long way to reduce genset time. The current price is $199 for one 100 watt panel. I have seen the prices drop 25% in the last four months on semi flexible panels. So thats about $1500 for panels and controller. The attachment to the canvas is currently an unkown price for me. There are several companies who have done this for sail boats, so the methods for attachment have been figured out.
Semi Flexible 100 Watt Solar Panel 12V High Efficiency Sunpower | eBay
Solbian uses Sun Power cells (the most efficient commercially available) mounted in flexible plastic - these are not the kind sold at West and elsewhere that roll up or can be walked on - those are quite inefficient. Solbian has a total solution, including brackets to hold the panels to your Bimini (with air space underneath). These are costly, but the best solar solution to mounting on top of a Bimini.

Solbian Flex
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Old 11-15-2013, 03:36 PM   #29
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Shore Power Independence-2

Hi Reuben,
Yes, the battery charging has been double counted. Iíll eliminate that which brings the total power load down to 19.5 kWh. I was following the tables in the Voyagerís Handbook and thatís the way they did it. But then, as you point out there are about 15% charging losses so the total goes back up to 19.5 +0.15 x 5 = 20.25 kWh.

The air conditioning is a bit more complicated. I have five AC units totaling 65,000 BTU. If all five are running full blast they draw 65 amps at 120 volts. Thatís 7.8 kW. During the day I normally only run the air conditioning in the upper and lower salon which have 40,000 BTUs of air conditioning and draw 38 amps But these units are on thermostats and cycle on and off so itís difficult to figure out how much power they draw. On a 90 degree day they run full blast and draw 38 amps (4.6 kW). At night the AC loads drop dramatically and I estimate about a 2kW average AC load. For a 24 hour day that makes the total aid conditioner load (16 x 4.6 + 8 x 2.0) = 89.6 kWh/day.

Air conditioning estimates are pretty much of a guess. But it doesnít make much difference what answer you get. Solar panel power systems canít even make a dent on the sun load. With generator power my Connie can just about break even on a 90 degree day but the noise of the air conditioning systems (not generator) is annoying. You have to make a choice; run the generator and put up with the air conditioner noise or turn off the generator and sweat. We find that fans are very useful. They can even be run on battery power. My air conditioner estimate of 5.4 kW is woefully low. It reflects running a lot of fans and running the master stateroom air conditioner for a couple hours before going to bed.

I donít have a water maker. The estimate is just for those of you that do. But with 160 gallons I can probably make it for a week if I donít take too many showers. The Handbook p.326 recommends 75 to 150 gallons for a couple on a trip of 30 days. I guess they donít take too many showers. If we run out of water we can always fall back on booze. Many of us do that even when there isnít a shortage of water.

Solar panels do provide an alternate source of power but only about 1.2 kWh per day (Handbook p. 235). Battery banks do the same thing. Four fully charged 150 Ah 6 volt golf cart batteries store 600 Ah or 3.6 kWh which equals 3 days of clear weather solar power

At $8 (about 2 gallons) of fuel a day and a 400 gallon fuel reserve Iíll only have to dinghy ashore to get fuel once every 200 days (less than two times a year). I donít think thatís going to be a big problem.

Letís consider your ďClean Sheet of PaperĒ comments.

1. Small wind turbine: They donít seem popular with the blue water sailors Ė solar panels are preferred and at $4K they are almost as expensive as a small diesel generator.

2. Solar power : A good source of alternate power in case the engines break down. Popular with the blue water sailors.

3. Small diesel generator: An excellent choice for alternate power. They start at about $4k, provide 4kW to 6 kW, work in any condition, are quiet and provide additional resale value to the boat.

4. High amp alternators: Fairly popular with blue water sailors; provide up to 300 Ah (3.6 kW) each, can be installed on both engines for redundancy. But they have high belt failure rate and run the main engines at low power output causing premature engine wear and failure. A good emergency source but donít use them regularly.

5. Big Auxiliary Battery Bank: Almost a requirement for off shore power independence. All of the blue water cruisers seem to have very large battery banks.

6. More Efficient Fridge: Yes, by all means change your old fridge out and replace it with a new one. They only burn about 30% of what an old one does. But, paradoxically, if you have a large generator all it will do is reduce your fuel burn rate by a small amount. And, if the fuel cost savings are small the savings may not pay for the swap out of the fridge for several decades.

7. More efficient lighting: Iíve been changing out my incandescent lights for several years and replacing them with fluorescents or CFLs. This is due more to longer lifetime than to efficiency. It means that I donít have to change them so often. Incandescent lights in a high vibration environment (such as an engine room) have a very short life. No point in changing out your old fluorescents though. They seem to last forever and have very good efficiency. LEDs are good but avoid halogen bulbs.

Pete37
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Old 11-15-2013, 05:04 PM   #30
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If you only plan on 36 days a year, that is 3 days a month, or one weekend a month. The generator choice is obvious. If you liveaboard 365 days a year as I do, the solar choice is obvious. I don't want to feed, listen to, or maintain a diesel genset. It goes back to how you use your boat. Their is no "one" right answer for everyone.
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Old 11-15-2013, 06:32 PM   #31
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Apt sized 120v refrigerator bought in Mexico is tolerant of voltage droop when at marinas in third world. 440amp at 12v battery bank (8 golf cart batteries, 6v sourced from Sam's) . 5KW gen set. Slowly changing to led lights. 1 hour of gen set time if we run main engines 3 hours. Less if we run main engines longer. 2 hours gen set time if we don't move the boat that day or if it is so hot and humid that we decide to cool off sleeping cabin before turning in. Gen time would be a little less if SheWhoMustBeObeyed could do without her nightly tv news and movie fix. 250 gallons of water. Moving around E coast of Mexico and Americas Great loop water has not been an issue. We stay in marinas about 2 nights a month.
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Old 11-15-2013, 10:29 PM   #32
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Apt sized 120v refrigerator bought in Mexico is tolerant of voltage droop when at marinas in third world. 440amp at 12v battery bank (8 golf cart batteries, 6v sourced from Sam's) . 5KW gen set. Slowly changing to led lights. 1 hour of gen set time if we run main engines 3 hours. Less if we run main engines longer. 2 hours gen set time if we don't move the boat that day or if it is so hot and humid that we decide to cool off sleeping cabin before turning in. Gen time would be a little less if SheWhoMustBeObeyed could do without her nightly tv news and movie fix. 250 gallons of water. Moving around E coast of Mexico and Americas Great loop water has not been an issue. We stay in marinas about 2 nights a month.
Wut you say?
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Old 11-15-2013, 10:49 PM   #33
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Apt sized 120v refrigerator bought in Mexico is tolerant of voltage droop when at marinas in third world. 440amp at 12v battery bank (8 golf cart batteries, 6v sourced from Sam's) . 5KW gen set. Slowly changing to led lights. 1 hour of gen set time if we run main engines 3 hours. Less if we run main engines longer. 2 hours gen set time if we don't move the boat that day or if it is so hot and humid that we decide to cool off sleeping cabin before turning in. Gen time would be a little less if SheWhoMustBeObeyed could do without her nightly tv news and movie fix. 250 gallons of water. Moving around E coast of Mexico and Americas Great loop water has not been an issue. We stay in marinas about 2 nights a month.
440 amp-hrs seem really low for 8-6volt batteries. Should be over 800 amp-hrs.
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Old 11-16-2013, 06:27 AM   #34
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fryedaze, you are probably right.

We have four Trojan T-105s, at 225 ah each, that comes to 450 ah at 12 volts. I wouldn't think Sam's batts would be much different per battery. So he probably has 800 to 900 ah.
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Old 11-16-2013, 07:21 AM   #35
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Perhaps the reference is to useable amps, ie, 880 total; 440 to 50% discharge
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Old 11-16-2013, 08:33 AM   #36
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It seems to me that personal preference is the deciding factor.

The "greenies" & "tech-heads" go with solar panels & wind turbines and consider energy efficiency.

The "rednecks" and "traditionalists" would rather use a generator and power hungry appliances.

Both calculate the advantages and costs to suit their own views, and won't be convinced otherwise unless the evidence is overwhelming.
In the end - shore power independence can be gained either way and the difference in cost is minimal.

Me - I'm the minimalist. I get by with a single solar panel, an alternator and two batteries. It does all I ask of it.
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Old 11-16-2013, 09:17 AM   #37
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Perhaps the reference is to useable amps, ie, 880 total; 440 to 50% discharge
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Old 11-16-2013, 09:40 AM   #38
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Three things:
  1. There are several Forum members that when they speak, best you listen. On this subject Reuben Trane is the go to guy.
  2. For those of us who are not normally within 15 degrees of the equator (or how about 40 + degrees?) good reliable gensets and diesel heat are pretty nice and solar panels a summer fling only.
  3. Why this desire to have large, cheap and inefficient refrigerators and then try to figure out how to power them? Downsize, throw away your leftovers, drink less beer and more gin/scotch and many problems go away.
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Old 11-16-2013, 09:50 AM   #39
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Yup, about 400 usable amps. I don't want to hurt them on the bottom and that last bit on the top goes in real slow. Sorry I didn't specify. I was just trying to point out that it doesn't take a lot of investment to spend most of your time on the hook. When in a no discharge area the size of my holding tank is the limiting factor.
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Old 11-16-2013, 10:28 AM   #40
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I just read most of this thread. Would you guys please get your units straight when you talk about energy. You are confusing energy rate- amps (A) or kilowatts (amps times voltage or KW) with total energy- amphours (AH) or kilowatt hours (KWh). Amps and amphours must be referenced to a specific voltage to be unambiguous.

Also the energy consumed is not rate times hours. It is average rate times hours. Almost all appliances operate at some duty cycle or hours of operation each day.

FWIW the most efficient (in terms of KW per cubic foot of space) refrigeration is the Danfoss based compressor refrigerators. These so called 12 V systems (the compressor actually operates at several hundred Hertz AC) are available in small bar sized units for casual overnight use to larger 10 cu ft stand up units. Dometic, Novocool, etc are some of the manufacturers.

These Danfoss compressor refrigerators shouldn't be confused with the LPG/AC/12V units mostly made by Dometic for RV use. Those are absorption cycle units and use heat produced by the LPG, etc to produce cooling. They are very, very inefficient on 12 V battery supply.

A middle sized Danfoss unit of 6 cu ft capacity will require anywhere from 50 to 100 amphours (each 24 hours and at 12V) to operate in a moderate climate depending on condenser type. The seawater cooled condenser type made by Frigoboat is the most efficient but these are not available as a complete refrigerator, only as a ice box conversion.

It is easily possible to be shore power independent, either with a genset running a couple of times each day or with a big solar array. You just have to use appliances that are made for marine use and are very efficient like the Danfoss refrigerators.

A big 10 cu ft stand up Danfoss refrigerator will probably consume 150 AH a day. Other house loads will be 50-100 AH daily. It will take about 1,000 watts of solar panels and probably 600 AH of battery capacity to get you through the cloudy days to be able to do this on solar. A genset will require a much smaller battery bank to cover periods in between genset running.

All of the above assumes no air conditioning.

David
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