In planning our full time cruising (liveaboard) my wife and I have problems in deciding the right approach to the question if we should invest in a genset. Please see our website, http://beneteauidylle1550.com , for more info about our plans. We have a Perkins 4-236 85Hp as the main engine, it is 10 years old but still running very well. In order to have AC 220 volt available onboard, we will be using a large battery bank of about 800 to 1000 amp/hours 12 volt, then getting our 220 volt AC via an inverter. The decision problem is how we are going to charge the batteries. We were almost sold on the idea of using the Whispergen (the Stirling engine concept), it looked very good, at the planning stage, with the free heating for water etc. Now we have heard that it is too expensive for what it gives in charging, i.e. not economic enough. As we do not have an unlimited budget, we are contemplating other systems as well. What about fitting our main engine with a large DC alternator (Balmar for example) then mounting a watermaker and a compressor for the freezer on the engine as well? Would we kill the main engine in doing so? What do other people do when the recharge large battery banks and still be friends with the neighbors at the marina. Running the main every day for an hour or two is not so popular and noisy too. We would be grateful if someone could advise in this matter and also give us different views on the various systems available for charging battery banks economically and environmentally sound and being independent of shore power. Chris and Béa Hamilton.
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Well, Chris, Tough Question.
I looked at the Whisper Genset also and found it interesting. USD, about $12,000 compared to a locally produced one without a sound shield for $3,500. I assume you could get a unit with soundshield for $6-8,000 USD depending on output. I also have a large battery bank, and a Balmar alternator. The one thing to remember is that with all those batteries, it will take a LONG time to bring them back, as I have found. I have a friend who put a 6KW Northern Lights. unit in his boat, with 220 output. Off that, he runs his water heater and 25 gpm watermaker. He may be a bit over-powered. A 4KW may have been better. A generator likes being run at full load. My bias would be to go with a conventional genset of 4KW with a good sound shield and water-seperator muffler. I would reduce the battery capasity to maybe 500-600 amps (not including start battery) for weight savings since you have on-board generation. I would still go to a high output alternator and three-stage regulator. I would use a 220 volt version of a watermaker of decent capasity and run it when the genset is on, or off your inverter when on the main engine. As for refrigeration, I'd also stick with a boat-voltage electrical system. Engine-driven systems have fallen from favor. Anyhow, that sytem would provide you quiet generator power, charging and output both, while still having back up from the main engine with a high output alternator driving your inverter. Good luck regardless. Rick D.
I looked at the Whisper Genset also and found it interesting. USD, about $12,000 compared to a locally produced one without a sound shield for $3,500. I assume you could get a unit with soundshield for $6-8,000 USD depending on output. I also have a large battery bank, and a Balmar alternator. The one thing to remember is that with all those batteries, it will take a LONG time to bring them back, as I have found. I have a friend who put a 6KW Northern Lights. unit in his boat, with 220 output. Off that, he runs his water heater and 25 gpm watermaker. He may be a bit over-powered. A 4KW may have been better. A generator likes being run at full load. My bias would be to go with a conventional genset of 4KW with a good sound shield and water-seperator muffler. I would reduce the battery capasity to maybe 500-600 amps (not including start battery) for weight savings since you have on-board generation. I would still go to a high output alternator and three-stage regulator. I would use a 220 volt version of a watermaker of decent capasity and run it when the genset is on, or off your inverter when on the main engine. As for refrigeration, I'd also stick with a boat-voltage electrical system. Engine-driven systems have fallen from favor. Anyhow, that sytem would provide you quiet generator power, charging and output both, while still having back up from the main engine with a high output alternator driving your inverter. Good luck regardless. Rick D.
Just curious...
What do you plan on doing with the 220 volts? And what are your other electrical demands? Brian
What do you plan on doing with the 220 volts? And what are your other electrical demands? Brian
Further explanation on 220 volt usage
Hello Brian, Well, the items I am going to use the 220 volt on are; Watermaker, washingmachine, microwave oven, two electric ceramic cooking hobs (I do not like gas inside a boat, except in emergency when no electricity avaiable), plus other light AC food machines like mixer, toaster etc. Hope this gives you an idea on our AC demand onboard. All the best, Chris.
Hello Brian, Well, the items I am going to use the 220 volt on are; Watermaker, washingmachine, microwave oven, two electric ceramic cooking hobs (I do not like gas inside a boat, except in emergency when no electricity avaiable), plus other light AC food machines like mixer, toaster etc. Hope this gives you an idea on our AC demand onboard. All the best, Chris.
Thanks Rick
Thanks for the input Rick, it does heel on to the side of using a standard DC genset. But we also have to compare the cost of the extra heating-system we have to install with a conventional genset, as to the "free" heat from the whispergen. Anyway I hope this will start a good discussion, from which we will learn a lot and have as a foundation for our final decision. Fair winds, Chris.
Thanks for the input Rick, it does heel on to the side of using a standard DC genset. But we also have to compare the cost of the extra heating-system we have to install with a conventional genset, as to the "free" heat from the whispergen. Anyway I hope this will start a good discussion, from which we will learn a lot and have as a foundation for our final decision. Fair winds, Chris.
re Engine as Generator
Even with large electrical loads my preference would be for a system that doesn't use the engine as the primary means for charging the batteries. Diesels like to be run at a fairly good load and running the Perkins at a low load is an expensive way to refill the batteries. Since heat and hot water is a major consumer of electricity have you considered something like one of the newer compact water heaters that can double as a space heater? Like the Espar, for example. The means to "top off" the batteries will probably be different from the bulk charging. Generators are good for that but for topping off I'd prefer solar panels to save wear and tear on diesel powered generators. They would also provide a small amount of redundancy in the event of engine problems. My slip neighbor friend has a Beneteau 45 with a BIG Northern Lights gen set in one of the aft cabins - and she doesn't even have air conditioning. If it was me, I'd try load management and go as small as possible and also have reasonable access for maintenance. Anyway, those are my thoughts.
Even with large electrical loads my preference would be for a system that doesn't use the engine as the primary means for charging the batteries. Diesels like to be run at a fairly good load and running the Perkins at a low load is an expensive way to refill the batteries. Since heat and hot water is a major consumer of electricity have you considered something like one of the newer compact water heaters that can double as a space heater? Like the Espar, for example. The means to "top off" the batteries will probably be different from the bulk charging. Generators are good for that but for topping off I'd prefer solar panels to save wear and tear on diesel powered generators. They would also provide a small amount of redundancy in the event of engine problems. My slip neighbor friend has a Beneteau 45 with a BIG Northern Lights gen set in one of the aft cabins - and she doesn't even have air conditioning. If it was me, I'd try load management and go as small as possible and also have reasonable access for maintenance. Anyway, those are my thoughts.
Update on max usage
A vey rough calculation on our maximum demand per 24 hours would be around 420 Ah. Just info for the guys who can calculate better than I can, the best plan for recharging the battery bank. Cheers, Chris.
A vey rough calculation on our maximum demand per 24 hours would be around 420 Ah. Just info for the guys who can calculate better than I can, the best plan for recharging the battery bank. Cheers, Chris.
The problem with engine/genset charging...
The problem with trying to bulk charge your house bank with the engine or the genset is that the batteries will only accept so much charge, regardless of how powerful the alternator is. A healthy battery that is 50% discharged will accept only 25% of its Ahour rating, and then only for a short period, < 10 minutes or so. As the charge increases, the internal resistance of the battery rises, too, and it will accept even less charge current. Without going into all the details, the upshot is that you'd probably be running your engine or your genset 6 hours per day, mimimum. That's a lot of kerosene turned into air pollution, and a lot of noise. A single wind generator wouldn't come anywhere close to replacing 500 aH per day. Adding 240 watts of solar panels to the wind generator wouldn't get you that much closer. However, adding both of these things might get your engine/genset time down to 2-3 hours. You'd have to do the calculations yourself based on how much you had to spend on solar and how large a generator you could accomodate. So, if you really need 500 aH of power a day, it looks like a genset is your only possible solution. If it were me, I'd be thinking of ways to reduce the load. Do you really need *all* the comforts of home? Paul sv Escape Artist h336
The problem with trying to bulk charge your house bank with the engine or the genset is that the batteries will only accept so much charge, regardless of how powerful the alternator is. A healthy battery that is 50% discharged will accept only 25% of its Ahour rating, and then only for a short period, < 10 minutes or so. As the charge increases, the internal resistance of the battery rises, too, and it will accept even less charge current. Without going into all the details, the upshot is that you'd probably be running your engine or your genset 6 hours per day, mimimum. That's a lot of kerosene turned into air pollution, and a lot of noise. A single wind generator wouldn't come anywhere close to replacing 500 aH per day. Adding 240 watts of solar panels to the wind generator wouldn't get you that much closer. However, adding both of these things might get your engine/genset time down to 2-3 hours. You'd have to do the calculations yourself based on how much you had to spend on solar and how large a generator you could accomodate. So, if you really need 500 aH of power a day, it looks like a genset is your only possible solution. If it were me, I'd be thinking of ways to reduce the load. Do you really need *all* the comforts of home? Paul sv Escape Artist h336
Balmar Genset
I don't have one (yet) but my solution would be a Balmar APC-752-12 or APC-754-12 DC genset. The -752- makes 20 g.p.h. and the -754- makes 40 g.p.h. of fresh, desalinated water. They are designed for use with inverters to 2,500 watts. The 3.5 kW unit will produce about 300 Amps of charging current and the rule of thumb is that you can charge AGM batteries at a current about 40% of their rated capacity in Ah. This indicates you could support a 750 Ah battery system with this device and charge it in an hour. A 1000 Ah battery bank would take longer to charge. A DC powered fridge/freezer would work well from the battery bank. Note that keel cooler refrigerator compressors are generally more efficient than air cooled ones. The Balmar genset is equipped with connections for a hot water heater as well so you can wake up in the morning, start your genset, charge the batteries, take hot showers and wash clothes and dishes in the hot fresh water made by the genset. Now all I need is the money. PS I'm not a dealer!
I don't have one (yet) but my solution would be a Balmar APC-752-12 or APC-754-12 DC genset. The -752- makes 20 g.p.h. and the -754- makes 40 g.p.h. of fresh, desalinated water. They are designed for use with inverters to 2,500 watts. The 3.5 kW unit will produce about 300 Amps of charging current and the rule of thumb is that you can charge AGM batteries at a current about 40% of their rated capacity in Ah. This indicates you could support a 750 Ah battery system with this device and charge it in an hour. A 1000 Ah battery bank would take longer to charge. A DC powered fridge/freezer would work well from the battery bank. Note that keel cooler refrigerator compressors are generally more efficient than air cooled ones. The Balmar genset is equipped with connections for a hot water heater as well so you can wake up in the morning, start your genset, charge the batteries, take hot showers and wash clothes and dishes in the hot fresh water made by the genset. Now all I need is the money. PS I'm not a dealer!
Whispergen
Based on you usage, I think I would go with the whispergen mostly because I would not to keep a normal Genset running all the time due to the noise. (inside the cabin and out)If the whispergen is as quite as they say it is, noise is not a problem and it will automatically provide power as soon as demand warrants. Remember also, when you are putting huge loads on the battery (1000 watts/100 amps) it actually drains the battery quicker than if you used that 100 amps at a rate of 2 amps/hour. So when cooking etc, you will need to plan on those batteries depleting faster. There is an excellent book by Don Casey that covers about everything you need to know about electrics on sailboats in very simple tersm. (see link) As far as gas on the boat,,,if you would be willing to use it instead of electric to cook, it would decrease your power usage dramatically. I don't see it as being unsafe either as I believe electrical fires are much more common than gas related fires.
Based on you usage, I think I would go with the whispergen mostly because I would not to keep a normal Genset running all the time due to the noise. (inside the cabin and out)If the whispergen is as quite as they say it is, noise is not a problem and it will automatically provide power as soon as demand warrants. Remember also, when you are putting huge loads on the battery (1000 watts/100 amps) it actually drains the battery quicker than if you used that 100 amps at a rate of 2 amps/hour. So when cooking etc, you will need to plan on those batteries depleting faster. There is an excellent book by Don Casey that covers about everything you need to know about electrics on sailboats in very simple tersm. (see link) As far as gas on the boat,,,if you would be willing to use it instead of electric to cook, it would decrease your power usage dramatically. I don't see it as being unsafe either as I believe electrical fires are much more common than gas related fires.
Thank you all
thank you all for very good information, it has answered a few questions for my future decisions. best wishes to all of you, Chris.
thank you all for very good information, it has answered a few questions for my future decisions. best wishes to all of you, Chris.
solar/wind available in the islands
Didn't see what your daily energy use was. I am planning to install solar for my trip, and perhaps wind, but definitely solar.
Didn't see what your daily energy use was. I am planning to install solar for my trip, and perhaps wind, but definitely solar.
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