Thanks Stu for these pointers. I've actually consulted your tutorial as I've put together this diagram and found it to be a clear and helpful summary. In terms of the tutorial by Maine Sail, I'd never run across that particular one, so thanks for this reference. In reading through that posting by MS it appears that with a diesel with a separate alternator one can run the alternator directly to the house bank. Given, though/ that my starter and alternator cable are one and the same thing, then I must run this starter/alternator cable to the Common, as I've drawn it in the diagram.
I enjoyed MS's words on HEF (Human Error Factor). He applies that term to the misuse of the 1/2/Both/Off Switch. I must say that, despite the fact that I've put lots of time into reading and researching this project, there is in the back of my mind no small fear that I have routed some cable in this diagram incorrectly. Recently a 37 foot boat dramatically burned and sunk in Charleston Harbor. The cause is still under investigation, but I continue to wonder if the causeof the fire was electrical. Here's some footage.
Thanks everyone for the help, and if you still see any HEF (Human Error Factor) in my diagram, please point it out and bring me to my senses. I don't want my boat to end up on the bottom of the harbor - or have to pay a salvage company to bring her up.
Because you have no inboard and therefore have no permanently installed underwater metal (shaft and propeller connected to engine block) the battery negative is your only ground point. A heavy wire from the negative post to a bus with all DC grounds connected to it is the only solution.
AC grounds should be kept separate and will rely on the shoreside ground. There is no advantage in your case to joining the AC and DC grounds.
My only further thought is that a SCS225 is more than you need for an emergencybattery that will seldom be used, or even if it will be used for starting. I would put the money into the house bank as you are but would buy a group 24 start battery for $50 or $60.
My thoughts too, you could start a 9.9hp outboard on a moped battery.
Since this yacht is 25ft? then I wouldn't bother with a reserve battery at all, honestly. Afterall the Yahama can be started by hand if needed. If the batteries run down you will see this on the battery monitor so just start the honda and charge them up. What you will save is lots of dollars and 30 kgs of weight for the SCS 225. The Yamaha will start on the 105s quite happily.
The two trogans will give a bank of 225 amps at 12v, so a usable capacity of 112 AH before needing to charge, which would be several days usage at our rate of 30 AH a day.
The other thing is that it keeps the electrics simple and follows the KISS approach.
...with a diesel with a separate alternator one can run the alternator directly to the house bank. Given, though/ that my starter and alternator cable are one and the same thing, then I must run this starter/alternator cable to the Common, as I've drawn it in the diagram.
Roscoe, essentially MS and I wrote the same things, he's in Maine and I'm in California. We've been discussing these issues for many, many years, and I'd "collected" them to avoid having to retype the same things, over and over again.
Your starter and alternator cables are the same because you have an outboard, right? Makes sense. It's no different than the disussion about diesel engines and the OEM installation of one cable from the C post to the starter with a small jumper to the alternator output.
What you've done makes sense, just so YOU know how it works and how to use it.
I enjoyed MS's words on HEF (Human Error Factor). He applies that term to the misuse of the 1/2/Both/Off Switch. I must say that, despite the fact that I've put lots of time into reading and researching this project, there is in the back of my mind no small fear that I have routed some cable in this diagram incorrectly.
It's always good to check. MS always recommends LABELLING all of the wires. I do it at both ends and in the middle, too. Makes installation a lot easier. And do it one step at a time and check as you go, rather than doing it al at once and wondering what may be snafued.
HEF? Shoot, maybe in one of those links I gave we had this discussion. I finally said: "If skippers can't learn how to use a simple switch, I contend that there are a LOT more complicated things to deal with on a sailboat." Really, if one can't remember to turn a switch, how does Bob or Joe manage to turn the lights on or off in his house? C'mon. I find that really a great big excuse for complacency and laziness. BTW, you have your ACR, too, so switching should ONLY be done BEFORE the charging starts, don't switch when the alternator is running.
I've sized the House Bank according to my amp hour chart (which I've not included in this posting). I have LEDs throughout the boat, so those aren't a problem. The amp hours climb, though, when I add up the other things: GPS, transducer, VHF, tiller pilot, several fans (for this hot and humid climate in which I live), and the biggie - an Engel DC fridge that I hope to include at some point. I prefer not to hunt for ice.
Based on other conversations I have had on this forum, the Iota 45 is an appropriately sized charger for this bank. A 6amp outboard alternator is not sufficient. I plan to power this charger with my Honda EU2000 when at anchor.
There are various schools of thought on grounding, but my decision to use a ship ground is based on the ABYC standards that are discussed in the link that I included in the earlier posting.
Stu provided a couple of links to diagrams that he and Maine Sail have drawn in the past. I used these as guides and I don't believe my diagram is any more complicated than those, except maybe in one area - the bilge pump switches. I raised a question on the Ericson Forum about what one would do if the bilge pumps were wired directly to the house bank and the house bank died. Maine Sail responded to that question by saying that it was unlikely that the house bank would die and the bilge would be needed at the same time. He said if that happened I could move the wires from the house bank to the reserve. He also said that I could install an A/B switch to switch the pumps from one bank to the next, but he suggested this was overkill. I know a boatbuilder/marine electrician here in Charleston, and he took a look at my diagram today. He said the same thing that Maine said, so I will likely remove this A/B switch from the diagram as a way to make things more simple.
Your diagram also says: "To ship's ground" but it doesn't show a termination point. One of the advantages of the wiring diagrams I previously posted, including Maine Sail's stuff, is that it shows the points of connection for everything. Especially the one from my Basic Battery Wiring Diagram topic: Basic Battery Wiring Diagrams
I respect your experience in electrical matters and I really appreciate you giving me a hand with this. Would you mind, though, explaining to me why the negative of my battery banks is the only ground available to me?
On the thread that I have included here again, I ask a very specific question about the proper grounding of my AC and DC systems with my outboard powered boat. Unless I am misinterpreting the responses given my Maine Sail, the approach I describe is correct according to ABYC standards.
Maine Sail wrote: The key is that the DC wires connected to that grounding point are not current carrying and just grounding wires. Only with an AC fault would AC current potentially pass through this grounding point and you'd hopefully spot the reverse polarity alarm/light quickly and fix the issue.
Since that si what you are doing, and that you have the negatives running to the batteries, and this is just an additional NONcurrent carrying wire, it is just fine.
Now I get it. Just see it rarely on outboard powered boats. Having that grounding plate on your E25 is unusual.
Stu is right - it is very unusual. There are many thousands of outboard powered boats - sail and power - that do not have that connection to use, and in the case of sailboats with internal ballast or powerboats with outboards, no option without it.
But keep in mind that it is not exactly "non current carrying" I don't think. It becomes a path for stray DC current. This is what causes galvanic corrosion on boats and is one reason so many in the link you provided - which I have read before and just re-read - refuse to connect the AC green wire to the DC negative bus, despite ABYC.
If you have any metal parts underwater - through hulls as an example - the connection of the AC green wire to the DC negative can introduce this corrosion as it creates a path for any stray DC.
You have not shown your planned AC system in any of the schematics you posted. Does it include a galvanic isolator? If not, with your planned connections, it should.
Mitiempo, since you asked about my AC Circuit, I thought I would post that diagram. There is no galvanic isolator. Where would you put it?
I also thought I'd include my Grounding Circuit diagram while I'm at it. In this you'll see how I lead DC, AC, and Lightning grounding all to the same point. Note that in this diagram I've made the DC grounding wire yellow to distinguish it from the green AC grounding wire. In the Main Circuit diagram which I've attached several times (and I'm attaching here again), I made the DC grounding wire green just to distinguish it from the yellow ground wires.
In this you'll see how I lead DC, AC, and Lightning grounding all to the same point.
How do these diagrams look?
The West Marine Advisor on grounding and bonding states:
The lightning ground needs to be a direct DC connection to the keel or to a ground plate to handle currents due to lightning strikes. So how do we keep the keel or ground plate electrically isolated as required in "Bonding and Electrolytic Corrosion..." above?
The solution is to connect the keel or ground plate directly to the mast, but make sure the mast is not electrically connected to the boats DC ground system. If your steaming light, masthead light, tricolor, Windex light etc. are wired carefully and correctly, they each will have their own DC return wire; there should be no ground connection between their wiring and the mast itself. Make sure that this is the case.