DC Generator - The Smart Way to Go

[Andrew Troup]

Originally Posted by SV THIRD DAY

Oh sure, HondaHaters are out there, but how long are the storm cells you have been in? There is this technology called an Engine and Alternator to make power in conditions you can't use the trusty Honda. If you are anchored close enought to be annyed by a Honda 2000...then it's time for you to move...you anchored too close...

I rest my case ...

[SV THIRD DAY]

Originally Posted by Andrew Troup

I rest my case ...

Generator case or Suit case....this is almost as much fun as making hot water at sunset pointing the Honda at the guy who just dropped anchor close enough to pass the cocktail...haha ha ...now that's funny....

[Andrew Troup]

... when, in point of fact, your are actually irritating the guy further downwind who was already there when you anchored but is resolving in future to avoid anchorages favoured by people who share your enthusiasm for hot water on tap and your disdain for peace and quiet.

You're right, this IS fun.

[SV THIRD DAY]

Actually their wife has already been aboard to bum a fresh water shower, so we already met her while the crusty "we don't need no stinking water" salt stayed aboard to enjoy his solitude....

[Andrew Troup]

Well I suppose that turn of events could have its compensations (speaking in the hypothetical third person)

That person could at least then fit his earplugs and/or play some Iron Butterfly ... (well, one Iron Butterfly)

Remind me what it was again, that stuffed things up in the garden of Eden?

Snakes bearing tales of hot water?

[Tayana42]

Regardless of the type of generator, portable or installed, there is a need to be considerate of others and not run them after sunset or too early in the morning. Same as with sound systems, loud partying in the cockpit late at night and yapping dogs left alone on board. Haven't we done this nose thread before?

Sent from my LG-P769 using Tapatalk

[ColdEH]

Hi Guys , just to update this thread I have adjusted my system somewhat.

I have now gone with a 600ah bank of Sinopoly LifePo4 batteries.

I sent the Regulator from the alternator back to Echo-Tech for a recalibration to suit the charge characteristics of the new batteries . These guys are great, they not only changed the set point of the charge cutoff but made it adjustable with a small potentiometer, excellent !!

Regards

[Xedis]

Originally Posted by ColdEH

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

Really l don't t understand all this it seems like everybody's back in the 1900s on this stuff the way that I understand it today DC appliances uses 10 times less at the most than AC appliances so I don't understand why you're changing DC to AC and if you are using AC appliances you should be changing to DC appliances because you can save over 50% energy on DC so it's kind of backwards changing DC to AC when you should be changing AC to DC

[Dockhead]

Originally Posted by Xedis

Really l don't t understand all this it seems like everybody's back in the 1900s on this stuff the way that I understand it today DC appliances uses 10 times less at the most than AC appliances so I don't understand why you're changing DC to AC and if you are using AC appliances you should be changing to DC appliances because you can save over 50% energy on DC so it's kind of backwards changing DC to AC when you should be changing AC to DC

Talk about a necropost! The last post on this thread was from 2014.


But since the thread is active again -- the efficiency of conversion of AC to DC or DC to AC is well over 90% with modern inverter/chargers. So contrary to what you write, it's not that important whether you are generating AC vs DC power. Nor is there a big difference in efficiency between AC and DC appliances. At least, not any advantage of DC -- AC motors are more efficient than DC ones, for example. Much more important to efficiency is the loading of the generator.


The one really big advantage of DC generators (and inverter generators like Hondas) is that the engine speed can be varied with load, which improves partial load efficiency compared to constant speed AC generators. But constant speed AC generators are fine if you do a little planning and group your tasks to keep the generator loaded up when you use it.

[tanglewood]

Originally Posted by Dockhead

The one really big advantage of DC generators (and inverter generators like Hondas) is that the engine speed can be varied with load, which improves partial load efficiency compared to constant speed AC generators. But constant speed AC generators are fine if you do a little planning and group your tasks to keep the generator loaded up when you use it.

And true much more for gas/petrol engines, and much less for diesel engines where fuel consumption varies more linearly with load.

[Bowdrie]

Originally Posted by Dockhead

Talk about a necropost! The last post on this thread was from 2014.
But since the thread is active again --

Jeepers, one of the "Oldie/Moldy" threads.
Dockhead, does this mean I can drag out of storage my ancient "Redi-Line" motor-generator?
I think Ben Franklin built it soon after he invented electricity.

[sailorboy1]

Have the DC generators before more affordable since the last death of this thread?

[Matt Johnson]

Originally Posted by sailorboy1

Have the DC generators before more affordable since the last death of this thread?

Nope. The quotes I got were insane when I looked about a year ago ($25k for a 10kw unit). A few new brands were shown at METS, but all looked to be reaching for the high end market with no attempt of improvement on pricing.

If I were in the market, I'd buy this guy and gut the system:

https://www.ebay.com/itm/275673814976

[GordMay]

Originally Posted by Dockhead

Talk about a necropost! The last post on this thread was from 2014.

But since the thread is active again -- the efficiency of conversion of AC to DC or DC to AC is well over 90% with modern inverter/chargers. So contrary to what you write, it's not that important whether you are generating AC vs DC power. Nor is there a big difference in efficiency between AC and DC appliances. At least, not any advantage of DC -- AC motors are more efficient than DC ones, for example. Much more important to efficiency is the loading of the generator.

The one really big advantage of DC generators (and inverter generators like Hondas) is that the engine speed can be varied with load, which improves partial load efficiency compared to constant speed AC generators. But constant speed AC generators are fine if you do a little planning and group your tasks to keep the generator loaded up when you use it.

Indeed - well said!

[Dockhead]

Originally Posted by tanglewood

And true much more for gas/petrol engines, and much less for diesel engines where fuel consumption varies more linearly with load.

Indeed.

But we also think about the health of the diesel engine, and there light loads on constant speed diesels are not a good idea.

That is surely another advantage of variable speed DC generators with diesel engines. Reducing RPM with light loads keeps the cylinder temp up because more fuel per stroke compared to the same load at higher RPM.