Shore Power Independence

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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.
 
Darylat8750 said:
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.
Click to expand...
Wut you say?
 
Darylat8750 said:
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.
Click to expand...

440 amp-hrs seem really low for 8-6volt batteries. Should be over 800 amp-hrs.
 
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.
 
Perhaps the reference is to useable amps, ie, 880 total; 440 to 50% discharge
 
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.
 
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.
 
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.
 
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
 
sunchaser said:
Three things:

  1. 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.
Click to expand...

:iagree:
 
Hi Readytogo,
I didn’t say that I planned to use my boat for only 36 days per year. I said that’s the number of days the average boater uses his boat each year. I use my boat about 240 days per year. But it does say (according to you) that at 36 days a year the generator is the obvious choice. And that’s why most boaters choose the generator route to shore power independence.
Darylat8750 has just made a post in which they indicate they have taken a generator route to shore power independence almost identical to the one I have suggested and it seems to be working fine. Their genny is much smaller than mine but still quite adequate to keep the battery bank charged. They have a 250 gallon tank (a bit bigger than my 160 gallon tank). The Voyager’s Handbook indicates that 150 gallons is adequate but I could probably add a deck tank if it proved necessary.
Way to Go Darylat8750! Hope SheWhoMustBeObeyed is enjoying her trip.
Pete37
 
Can run an old 12v Danfoss powered fridge on panels, the espresso coffee machine needs the genset.
On a Selene a while back, it had what seemed a "walk in" battery room as part of the ER. If they had the right panels I think they could power about anything, but they had a LOT of battery.
 
David,

You say a 10 cu. ft. Danfoss will use 150 AH/24 hours. This is 1.8 kWH/day. A modern Japanese household fridge with all the bells and whistles averages 50w/hour or 1.2 kWH/day. Even assuming inverter losses , energy use/cubic foot is less for the modern household unit. An added advantage is the design and quality of these units. Most marine units look as though they were designed in 1950.

My current thinking on electrical systems includes much of what I have previously posted:

1. Renewables - wind & solar where applicable.
2. Large LI battery - space and budget to determine.
3. Energy saving installations - lighting (a typical 25w anchor light consumes 2A/hour at 12v or 16A/8-hour night) - refrigeration - cooking (induction cooktop & the most efficient microwave/convection oven available - LPG if you're so inclined)
4. Auxiliary generator (sized to fit the boat and lifestyle) - in this case I prefer a variable speed DC generator that runs at the RPM appropriate to power needed at the moment. Auto on/off.
5. High amp alternator(a) on main engine(s).

What I haven't mentioned are the next steps:

1. Shore power does only one thing - charge the battery.
2. ALL 120/240v power is inverter supplied. Pick the most efficient unit(s) sized to meet max load.

What this does for you:

1. When you're in a minimal marina with voltage drops to your plug-in point, the battery charger will continue to work OK and ALL your AC power is massaged by the inverter with perfect voltage and Hertz.
2. There is NO change over when casting off (unplugging) from shore to boat power.
3. Ditto when starting or stopping the generator.
4. Much of the time underway, you will not need to run the generator.
5. Depending on BTUs of master stateroom A/C and battery size, you may be able to stay cool at night w/o running the generator.

Mastervolt has been working on a system that uses a variable speed generator married to a "black box" that coordinates shore, generator and inverter power. This is not exactly what I propose , but not dissimilar in approach.

Obviously, with installed systems, converting may be cost prohibitive. But could be done in steps as major items need replacing - batteries - generator - fridge, etc.

Much more feasible with a new build.

Our Island Pilots were fitted with;
1. 4 each 8 D AGM battery's for close to 1,000 AH capacity.
2. 2 kW inverter chargers.
3. Hitachi or Toshiba efficient 14 cu. ft. Fridges.

These modest outfitting decisions allow for 24 hours on the hook w/o running the generator. Both engine alternators charge the starting and service batteries. Generator is run to cook and cool, charging the batteries during meal prep, laundry time or making water.
 
rjtrane said:
4. Auxiliary generator (sized to fit the boat and lifestyle) - in this case I prefer a variable speed DC generator that runs at the RPM appropriate to power needed at the moment. Auto on/off.
Click to expand...
When I was following the diesel-electric subject more intently, I recall Glacier Bay was a big proponent of these DC generators. Are there many suppliers of such units out there now? I haven't looked at this subject in a long time.
 
Glacier Bay is not promoting its serial diesel electric system that I know of. When we sea trialed a system , it did not perform as intended.

Fischer Panda is big in DC generators and diesel electric propulsion. There are several others , also. I can get you info if interested.
 
"Darylat8750 has just made a post in which they indicate they have taken a generator route to shore power independence almost identical to the one I have suggested and it seems to be working fine. Their genny is much smaller than mine but still quite adequate to keep the battery bank charged."

I will point out that I went this route because the equipment was mostly already on the boat. I replaced the refrigerator because the old 12/120 volt one quit working while I was in Mexico. A new 12v unit imported into Mexico was more than $2000. The apt. sized 10cu foot from the local big box store was $239. I replaced the old inverter when it failed with a new one (have had the old one fixed and keep it as a spare) and replaced the batteries. If I were starting from scratch I would try to go with a very robust 24v DC system and solar. I looked into LPG refrigerators but because of our galley set up I had concerns about proper ventilation without messing up the looks.

My friend who lives aboard full time (almost exclusively at anchor) just put in a new "high efficiency" (I think Samsung and it's as big as the one in my house) inverter technology refrigerator. It has a small door and a large door in the ref. compartment and a drawer for the freezer. The things that get used a lot are put behind the small door so less energy is lost with the often used items. He is also working on replacing his old watermaker with a new high efficiency one and adding some solar panels. When he gets the modifications made he is hoping to reduce genset time from 2.5 hours a day to a couple of hours on the days when the laundry needs to be done. They only use airconditioning when the genset is running and not often even then. I think that he has a good chance at making it work. When he gets all the modifications done I'll ask him to give us a report.
 
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Suchaser-if you drink enough gin/scotch (bourbon in my case!), even if the problems don't go away, you won't care.
 
Shore Power Independence Summary​

Well, we’ve been posting on this subject for a couple weeks now and have reached more than 50 posts. I knew a lot about shore power independence from five years of posting on another forum and now I know a lot more. One thing that was surprising was that in the past five years no one even suggested achieving shore power independence by using solar power.
I think we’ve pretty much exhausted the subject and now it’s time to summarize what we’ve learned. Basically, the group engaging in the forum was composed of the owners of 40’ to 60’ motoryachts and trawlers. Nearly all were diesel powered and nearly all (>95%) also had diesel generators. There were a few sailboats and a few smaller boats.
I started out by mentioning that I already had a motoryacht that was basically shore power independent. She is 50’ long, weighs 54,000 lbs. (24 tons) and is powered by a pair of 530 hp. diesels. There are two large salons, three staterooms and three heads. All are fully air conditioned. The staterooms sleep six but in case that isn’t enough the salons sleep four more; a total of ten. However, when anyone asks me how many she sleeps, I answer “Two, me and my wife.”. Basically, she’s a large motoryacht capable of housing two to six people in a very comfortable life style
To keep her properly powered when away from shore, she has a 20 kW Onan diesel generator capable of running all the electrical systems aboard. At full load it burns 2.1 gph and with 400 gallons of reserve tanks (used for anchoring out) I can anchor out for 190 hours (8 days). But realistically the average load on the genny is less than 2.0 kW (24 kWh per day) so the genny is only running at about 1/10th of full load on less than 0.25 gph. At this fuel consumption rate I can anchor out for 1600 hours (67 days). And if I were willing to live “sailboat style” much longer periods would be practical. The biggest problem with this mode of operation is that long term under-loading may cause damage to the generator’s engine. So she is, as I stated, “shore power independent”.
If we look at the rate at which power is used during the day, we find that most of it occurs in a 12 hour period from 7:00 AM to 7:00 PM which we call “daytime”. At 7:00 AM we arise and begin cooking breakfast. This lasts until about 9:00 AM after which power consumption drops drastically. At 11:00 AM power consumption rises quickly as we prepare the midday meal (lunch) and remains high until about 1:00 PM when lunch is finished. And again at 5:00 PM power consumption rises quickly as we prepare the evening meal (dinner) and remains high until about 7:00 PM when dinner is finished.
A logical way to take care of daytime loads is handle them in three short periods (breakfast, lunch and dinner). By doing this we avoid long term operation of the generator at low loads. During daytime we run the generator three times and generate 18 kWh. If each period is 1 hour that is a rate of 18/3 = 6.00 kW. This is still a light load of only 33% of full load but it is much better than running at 10% of full load. Fortunately nearly all the galley appliances are AC powered so meal preparation does not require much in terms of DC loads.

Between, 7:00 PM and 7:00 AM there is a period of 12 hours we call “nighttime”. There isn’t much power consuming activity between 7:00 PM to 11:00 PM. This is relaxation and entertainment time. We read, watch TV, talk listen to music, etc.
From 11:00 PM to 7:00 AM we sleep and other than a few small lights there aren’t any AC loads. DC loads are very small too and are easily handled by the house battery banks of most boats. The major power load is refrigeration which ranges from about 1.2 to 2.4 kWh depending on the efficiency of the refrigeration equipment. Roughly speaking if we assume a daily power consumption of 24 kWh we use about 3/4 of the power (18 kWh) in daytime 7:00 AM and 7:00 PM and about 1/4 (6 kWh) in nighttime.
A possible limitation on Interlude is that she has only 160 gallons of water, which according to The Cruising Handbook is good for only 60 person days. And my holding tank does not have unlimited capacity. So after about 30 days I’d have to make a brief shore stop to take on water and dispose of sewage.
Another, problem is food. She has a 20 cu. ft. refrigerator/freezer which could be kept during daytime by running the generator about 4 hours a day but I doubt it could hold a month’s worth of supplies.
At the moment none of these limitations seems severe enough to require modifications. We keep the boat on the Eastern Seaboard and in most cases supplies will never be more than a few hours away. The main purpose of shore power independence at present is to eliminate dockage fees. Later, when (and if) we become blue water sailors and world circumnavigators we will have to make some modifications.
However, fuel, if you are making long distance nonstop legs (such as in an ocean crossing) is a problem. Fuel consumption can be reduced and miles per gallon increased by reducing the speed but about 1 nmpg is about the best you can hope to achieve. Going slower than that, your engines do not achieve full operating temperature and you are at risk of engine damage. With only 600 gallons of fuel and reserving 100 gallons of that for producing electric power, the best distance you can hope for is about 500 miles. Beyond that you have to resort to temporary deck tanks.
We haven’t said much about them but there are three doldrums periods which total 17 hours. These are the periods when you have no AC power; 9:00 AM to 11:00 AM, 2:00 PM to 5:00 PM and 7:00 PM to 7:00 AM. Fortunately for the last of those periods you’re asleep anyway so you don’t need much AC. However, if you get bored you can turn on the generator any time you want.
But most of us don’t want the generator running just to power a fan or reading light. There should be some system that would power small AC loads when the generator is off. This is what is called an Inverter system. It takes DC power from a battery bank and converts it to AC. For a 50’ boat the rating should be at least 1000 watts. Unfortunately the design and/or selection of an inverter system is a very long and complex subject which I don’t want to discuss now. I’ll leave that for another forum topic.
However suitable units are available for about $500 and up from Maxwell, Xantrex and other manufacturers. Price of course varies with the amount of power you want to invert. And in addition to the inverter a battery bank to service the inverter is required. When the battery bank is included prices start at about $1000.
Pete37
 
I think you've summed it up pretty well. I will add that if you eliminate air conditioning the major electrical load that is left is refrigeration and that can be run off batteries or batteries through an inverter with the charging done by a gen set using (in my case) less than a gallon of diesel fuel a day or by solar or a combination of the two.
 
djmarchand said:
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
Click to expand...

I'll have to go thru this very interesting subject thread in more detail when I have more time. But this subject of the Danfoss compressors caught my attention as I remember listening to a fellow at the Annapolis boat show several years ago talk about the efficiency (and simplicity) of these newer refrig units verses the older holding plate systems.

I've wondered at times what might be involved with replacing the 'stock compressor/refrig guts' of a conventional household refrigerator with one of these modern Danfoss systems?....use the very nice 'box' of the modern household refrig with a more energy efficient compressor package? One might even add additional insulation to the outer surfaces of the 'house box' if there were some changes to the evaporator system made also (water cooled)?
 
Its too bad this subject thread is posted under the 'Chris Craft' heading rather than the 'Other Trawler Systems' heading ....IDEA
 
brian eiland said:
I've wondered at times what might be involved with replacing the 'stock compressor/refrig guts' of a conventional household refrigerator with one of these modern Danfoss systems?....use the very nice 'box' of the modern household refrig with a more energy efficient compressor package? One might even add additional insulation to the outer surfaces of the 'house box' if there were some changes to the evaporator system made also (water cooled)?
Click to expand...

These are looking like a good alternative
beier | eBay
Modern looks, 12 volt and relatively cheap.
There have been promising reviews on cruisers forum as they have had a few years of use now.
 
brian eiland;195786 I've wondered at times what might be involved with replacing the 'stock compressor/refrig guts' of a conventional household refrigerator with one of these modern Danfoss systems?....?[/QUOTE said:
I looked into this for Bay Pelican. Found you needed the compressor, a conversion kit and a controller. Forget the price but it may have been around $700 per unit. Decided to buy Isotherm units with the correct compressors instead.

Marty
Click to expand...
 
Nigel Calder published "Refrigeration for Pleasureboats" some years ago. Detailed theory, design, construction, comparisons of the various types of boat refrigeration. I think mine came from Amazon. It could use an update, but still very helpful.
 
The inverter, variable-speed compressors used in high-end Asian refrigerators are quite efficient. My guess is that they use similar technology as the inverter compressors from Danfoss.

They are available in Taiwan 120 VAC/60Hz from a variety of electronics manufacturers. We have used both those from Toshiba and Hitachi.

Why try to cobble together a fridge when very highly skilled engineers have already done this? These units have all the features found in the best US brands while using less energy.

And, since Asian kitchens tend to be small, many of these units fit in a 24"x24" footprint.
 
Hey Parmenter is that cat of yours a Compucraft?
If not what design?
Must admit one of the better looking power cats around.
Would love to see a lot more detail of her. Great Qld coast cruiser from the look of it.
Cheers
Benn
 
Tidahapah said:
Hey Parmenter is that cat of yours a Compucraft?
Click to expand...
That picture is of a 46 ft Brady cat, similar in style to a compucraft cat, similar in style to a Hodgens cat, similar in style to an Appleby cat, similar in style to a Stanyon cat, similar in style to mine.
If not what design?
Click to expand...
Its my own design with inspiration from many ;)
Would love to see a lot more detail of her.
Click to expand...
Not much to give.
Length 49ft 11
Beam of 22ft
Draft of around 1 metre +- and able to be dried out for maintenance with no problem.
Displacement approx 9000kg
Motors 80hp x 2
Fuel approx 2000 litres in 4 main tanks + 2x 200 litre day tanks

Western red cedar and epoxy to 200mm above the waterline and polycore above that, fitout is in gaboon ply, polycore, cedar.

Her length being one inch short of 50ft was to avoid this rule
I have no idea how much that would cost but it sounds expensive
All recreational ships more than 15m but less than 35m in length must have an insurance policy that provides A$250,000 for pollution clean up and A$10,000,000 for salvage and wreck removal.
http://www.msq.qld.gov.au/Registration/Ship-insurance.aspx
Click to expand...

Great Qld coast cruiser from the look of it.
Click to expand...
Should be and I intend to take her a bit further afield than that.
 
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