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Old 07-08-2011, 09:31   #1
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DC Generator - The Smart Way to Go

Started with a three cylinder Yanmar with a hundred hrs on it, that came off a Kohler genset . The electrical component was wired incorrectly and blew the windings , so I bought the engine from the Kohler installer. The engine idles at 1500 rpm no load and 1800 under load. Has a built in governor that controls this. So it is essential to use an engine from a generator

I am attaching a Eco-tech alternator to the crank via a lovejoy connection, above that will be a Hydracell D10 pump for my watermaker . This will be driven by an electric twin Vbelt clutch off of the same output shaft that the the alternator is connected to . Mantenance will be nearly nothing, the pump is only running at 30% of its capacity and the Hydra cell pumps last forever. The double belt is overkill as the pump will only draw around 2.5 HP. The alternator will draw around 8 hp but there are no belts so no side loads to worry about . This will load up the Yanmar to around 80% just were they like it for maximum life and fuel economy.

So the height will be a little higher then your stock 8 kw genset , but not by much . Looks like I will have the room. I am building a sound proof box around it and using Glacier Bays Ultra Db sound deadener in the box . Also using a gensep muffler that seperates the water from the exhaust so you don't get that splashing outside the boat when your generator is running . All this will give me 255 amps of charging power and 40 gallons of water with one hour of running.

I can't really understand why you would have an AC generator on a small sailboat. As small, I mean anything under 75 feet , bigger then that and you just leave the ac generator on all the time. But us, without deep pockets, have to conserve our energy and our diesel. So that means storing your energy in batteries .

So I ask, why use an AC generator to make power then change it to dc to charge your batteries, its nuts! And to just fire up a big genset to make toast? Thats nuts too. So that means you should have a very good inverter on board something like a Victron or a Mastervolt . Leave that on all the time for your AC power , good ones use nothing at idle, and draw all your power from your batteries. You should have at least 1000 ah of batteries so they can handle the high current charging. Get that power back in there as fast as you can so you don't have to run the engine for very long.

So again it turns out the smart thing to do with a genset is to optimize it to make as much dc power as you can, with every hp the engine has, and full use of the power per dollar of diesel fuel you use.

But try to find a powerful DC generator. No such thing.

So this was my solution

Update..... Glacier Bay does not sell Ultra db any more, I have to find a new source, any ideas?

Regards
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Old 07-08-2011, 09:46   #2
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Re: DC Generator - The Smart Way to Go

Polar Power makes them:
Polar Power Inc.- DC Generators, Battery Chargers, Solar Refrigeration, Photovoltaic Systems, Fans & Blowers, Metal fabrication
If you are in the scavenging mode, many big dc motors can be rewired into a dc generators.
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Old 07-08-2011, 09:47   #3
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Re: DC Generator - The Smart Way to Go

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. . . I can't really understand why you would have an AC generator on a small sailboat. As small, I mean anything under 75 feet , bigger then that and you just leave the ac generator on all the time. But us, without deep pockets, have to conserve our energy and our diesel. So that means storing your energy in batteries . . . . Regards
I suppose it all depends upon what you call a "small sailboat." Under 75 ft LOA is rather expansive for the term. IMHO, "small sailboat" is under 30 ft LOA.
- - But anyway when you get up into LOA's in the high 40's and above I notice a tendency of the owners/cruisers to start adding "comforts of home" type stuff like TV's, Home surround systems, washing machines and dryers, ice makers, and a whole "Best Buy" store full of stuff not to mention Air conditioning and AC watermakers. So an ac genset becomes a necessity unless you are willing to carry mega-amphours of batteries and multiple inverters as there is a limit to the maximum output of most inverters.
- - Batteries are not cheap and having a massive amount of them is both expensive and a maintenance challenge. Having a good ac genset is not that expensive when comparing costs and it lasts a lot longer. My BetaMarineNC genset has purred along for almost ten years with only fuel and oil filter servicing. And it has more hours on it than my main engine has accumulated during those same years.
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Old 07-08-2011, 10:03   #4
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Re: DC Generator - The Smart Way to Go

Nice work. But I have some questions. I'm irritating that way:

Why 1800 RPM? The Yanmar is coasting along at less than half power. A DC generator doesn't require a specific RPM like an 60Hz alternator might.

Don't 'all' diesels have governors? That can be easily set to any RPM?

You write "Maintenance will be nearly nothing." Is this not just too tempting to Neptune?

You make a claim of conserving energy, yet isn't charging batteries is far less efficient than running a smaller generator when power is needed?

Isn't one big advantage of alternators that they are far more reliable and require far less maintenance?

And aren't alternators easier to regulate than big DC generators?

What is the advantage of a 40 GPH watermaker over a smaller, lighter, cheaper, quieter 7 GPH, or even smaller, watermaker unless one requires several hundred gallons per day?
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Old 07-08-2011, 10:17   #5
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Re: DC Generator - The Smart Way to Go

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Nice work. But I have some questions. I'm irritating that way:

Why 1800 RPM? The Yanmar is coasting along at less than half power. A DC generator doesn't require a specific RPM like an 60Hz alternator might.

Don't 'all' diesels have governors? That can be easily set to any RPM?

You write "Maintenance will be nearly nothing." Is this not just too tempting to Neptune?

You make a claim of conserving energy, yet isn't charging batteries is far less efficient than running a smaller generator when power is needed?

Isn't one big advantage of alternators that they are far more reliable and require far less maintenance?

And aren't alternators easier to regulate than big DC generators?

What is the advantage of a 40 GPH watermaker over a smaller, lighter, cheaper, quieter 7 GPH, or even smaller, watermaker unless one requires several hundred gallons per day?
No problem.

No your main engine has no " governor" You set the throttle and it stays there, add more load and it slows down , the governor is like an autopilot for your engine, keeps rpm the same regardless of load. Most generators have two settings hi and low , or 1500 and
1800 according to the load.

Hey I dont want to start and stop my generator for a piece of toast then in a hour for the hair dryer. Inconvenient. Hard on the engine, if you start it, run up to temperature and under a proper load.

The Echo-tec is an alternator , rectified and regulated. Just a big one LOL

Check the maintenance schedules for those 12v small watermakers they require rebuilding after so many hours . If you run one all day for 20 gallons of water they reach the rebuild time very quickly . The pumps wear. Hydra cell pumps don't have pistons. I can make 40 gallons in an hour . Rebuild time will never come .

Regards
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Old 07-08-2011, 10:22   #6
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Re: DC Generator - The Smart Way to Go

Sorry missed one .

There are high rpm genrators, and low rpm ones .

The high rpm around 3000 are usually small , the big ones run slower max 1800 and the motors last much longer. The engines life span is based in part to how many times it has gone around, everything wears. Slower is better. And quieter.

regards
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Old 07-08-2011, 10:23   #7
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Re: DC Generator - The Smart Way to Go

"I can't really understand why you would have an AC generator on a small sailboat. As small, I mean anything under 75 feet , bigger then that and you just leave the ac generator on all the time. But us, without deep pockets, have to conserve our energy and our diesel. So that means storing your energy in batteries ."

Well, when I converted my 30 foot sailboat to Electric Propulsion four years ago I wanted to have a way to charge my 48 volt (10 kw) propulsion bank and my 12 volt house bank. I could have bought a diesel generator and installed it down below. But, one of the reasons I converted to electric propulsion is because I was too damn tired of squeezing my 6 foot 2 inch frame down below to do the repair and maintenance on the old Westerbeke. I decided to try using a Honda 2000 generator to see if it would meet my needs and it does. My backup plan was I could always install a diesel generator at a later date if it didn't.

Some of my reasoning for going this route was:

1) At 47 pounds it's very lightweight and compact.
2) Don't have to squeeze below decks to do routine maintenace on it.
3) If it requires repair beyond my abilities I can carry it off the boat myself.
4) For the price of an on board diesel generator I could buy five Honda 2000's and have backups into the after life.
5) If it died in the middle of a cruise I could have one shipped in or buy a replacement locally.

I actually don't need to use it that often as I also have solar and wind taking care of a lot of my charging needs on board. As far as fuel I went the other way and don't carry an ounce of diesel on board anymore. Just two 2.5 gallon jerry jugs of gas for most cruises. I find gas easier to find in some locations and I can use it in the dingy outboard too. May not work for others but, it certainly works for me.
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Old 07-08-2011, 10:28   #8
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Re: DC Generator - The Smart Way to Go

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Originally Posted by osirissail View Post
I suppose it all depends upon what you call a "small sailboat." Under 75 ft LOA is rather expansive for the term. IMHO, "small sailboat" is under 30 ft LOA.
- - But anyway when you get up into LOA's in the high 40's and above I notice a tendency of the owners/cruisers to start adding "comforts of home" type stuff like TV's, Home surround systems, washing machines and dryers, ice makers, and a whole "Best Buy" store full of stuff not to mention Air conditioning and AC watermakers. So an ac genset becomes a necessity unless you are willing to carry mega-amphours of batteries and multiple inverters as there is a limit to the maximum output of most inverters.
- - Batteries are not cheap and having a massive amount of them is both expensive and a maintenance challenge. Having a good ac genset is not that expensive when comparing costs and it lasts a lot longer. My BetaMarineNC genset has purred along for almost ten years with only fuel and oil filter servicing. And it has more hours on it than my main engine has accumulated during those same years.
How many hours do you have on your generator?? I know Betamarine's are great , they have huge flywheels.

I figure a 3000 Victron inverter should do all my ac needs on board unless im using 2 high powered things at the same time. No maintenance with AGMs. Batteries 2100$ and the inverter about the same. Hope to get 10 years out of the batteries.

Regards
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Old 07-08-2011, 10:32   #9
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Re: DC Generator - The Smart Way to Go

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Originally Posted by mbianka View Post
"I can't really understand why you would have an AC generator on a small sailboat. As small, I mean anything under 75 feet , bigger then that and you just leave the ac generator on all the time. But us, without deep pockets, have to conserve our energy and our diesel. So that means storing your energy in batteries ."

Well, when I converted my 30 foot sailboat to Electric Propulsion four years ago I wanted to have a way to charge my 48 volt (10 kw) propulsion bank and my 12 volt house bank. I could have bought a diesel generator and installed it down below. But, one of the reasons I converted to electric propulsion is because I was too damn tired of squeezing my 6 foot 2 inch frame down below to do the repair and maintenance on the old Westerbeke. I decided to try using a Honda 2000 generator to see if it would meet my needs and it does. My backup plan was I could always install a diesel generator at a later date if it didn't.

Some of my reasoning for going this route was:

1) At 47 pounds it's very lightweight and compact.
2) Don't have to squeeze below decks to do routine maintenace on it.
3) If it requires repair beyond my abilities I can carry it off the boat myself.
4) For the price of an on board diesel generator I could buy five Honda 2000's and have backups into the after life.
5) If it died in the middle of a cruise I could have one shipped in or buy a replacement locally.

I actually don't need to use it that often as I also have solar and wind taking care of a lot of my charging needs on board. As far as fuel I went the other way and don't carry an ounce of diesel on board anymore. Just two 2.5 gallon jerry jugs of gas for most cruises. I find gas easier to find in some locations and I can use it in the dingy outboard too. May not work for others but, it certainly works for me.

Cool, what kind of batteries are you using ?

Regards
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Old 07-08-2011, 10:43   #10
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Re: DC Generator - The Smart Way to Go

Boy that's a pretty big one! Good Idea. I've built two of these in the past from a Kubota 8 hp one cyl horizontal engine and one from a two cylinder 12hp Kubota. All belt drive. You dont need a AC gen engine. One of mine had the watermaker pump on it also. (electric clutch) It's a great solution and my smaller units weighed in under about 130 lbs total! You could fit it in the lazzarette. If you get your sheave size right, once you have pounded the high amps in you can adjust the rpm down to a smooth, quiet level to do the float charging. I think direct drive might be best though. An aircraft vernier throttle control works well. Like a push/pull knob with a lock and fine adjustment. Ample Power used to make these units from the small kubota engine and may still do so.... then again, the Honda 2000 kinda makes all this obsolete as mentioned above.... to bad theyre not diesel!
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Old 07-08-2011, 10:47   #11
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Re: DC Generator - The Smart Way to Go

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Boy that's a pretty big one! Good Idea. I've built two of these in the past from a Kubota 8 hp one cyl horizontal engine and one from a two cylinder 12hp Kubota. You dont need a AC gen engine. One of mine had the watermaker pump on it also. (electric clutch) It's a great solution and my smaller units weighed in under about 130 lbs total! You could fit it in the lazzarette. If you get your sheave size right, once you have pounded the high amps in you can adjust the rpm down to a smooth, quiet level to do the float charging. I think direct drive might be best though. An aircraft vernier throttle control works well. Like a push/pull knob with a lock and fine adjustment. Ample Power used to make these units from the small kubota engine and may still do so.
Crap mines weighs way more then that LOL . The pump and the alternator weigh 80 lbs .

I had a friend who did the same as you and it worked great for him as well.

Had to direct drive it , couldnt think of a way to belt it without eating the end crank bearing.

Regards
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Old 07-08-2011, 11:58   #12
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Re: DC Generator - The Smart Way to Go

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Cool, what kind of batteries are you using ?

Regards
I've use 4 8A4D AGM's in series for the propulsion bank and have two group 29 GEL's for the house bank. All are MK.
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Old 07-08-2011, 12:12   #13
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Re: DC Generator - The Smart Way to Go

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How many hours do you have on your generator?? I know Betamarine's are great , they have huge flywheels. . . . Regards
I have over 3500 hours on my BetaMarineNC genset. And I have been tempted several times to add a high output marine alternator to the unit for battery charging.
- - Making 120VAC and then using a shore power charger to convert it back to DC doesn't seem all that efficient besides which the battery chargers don't last that long. Since I use a lot of AC I have 80 amp battery chargers which are not cheap.
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Old 07-08-2011, 12:19   #14
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Re: DC Generator - The Smart Way to Go

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I have over 3500 hours on my BetaMarineNC genset. And I have been tempted several times to add a high output marine alternator to the unit for battery charging.
- - Making 120VAC and then using a shore power charger to convert it back to DC doesn't seem all that efficient besides which the battery chargers don't last that long. Since I use a lot of AC I have 80 amp battery chargers which are not cheap.

3500 still just a baby

I have friends that have almost 10000 hrs on there gensets, diligent maintenance. Well treated we all hope to get those kind of hours.

I agree , every time you change your electricity ac to dc and back again, you always loss some to heat .

Regards
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Old 07-08-2011, 16:51   #15
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Re: DC Generator - The Smart Way to Go

Why run a generator to charge your batteries? Wind and solar is a lot quitter and use a whole lot less fuel.
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