Rewiring a Cruising Monohull (Input appreciated)

[SVTatia]

Originally Posted by steve77

...

6) No one has discussed terminating all of these cables and what type of crimper to use, but a search on this forum will uncover several threads covering that topic....

Steve

On this topic I spent several boat bucks on the crimpers but worth every penny. The battery crimper was specially pricey, but I think I'm at a few cents a crimp if I divide the cost to the number of crimps I did...

Originally Posted by Intotheworld

Thanks. I used Microsoft Visio. I copied and pasted the images from google into my diagram. I am not familiar with technical wiring diagrams so having pictures of the product I'm actually using makes more sense to me. It should also make it easier in the future when I'm looking back at this and the pictures look like what is actually on the boat.

Do you start your engine with the house or reserve battery? I'm worried about what happens if I start the engine but have the house switch turned off.

Thanks - I'll need to redraw mine due to the many changes..

I use the 1-2-both as on-off always on 1 (house) or off. I never put it in both or 2 it is there just in case the house goes flat. So, yes, I always start the engine with the house and that is why the alternator is wired to it and its bus to the ACR input.

[mitiempo]

Originally Posted by Intotheworld

The 2 banks are on opposite sides of the engine so just changing one of the existing to house rather then a starter is not an option. All it takes is wire to make it a 3 battery house bank with a single start battery. Battery location, especially as close as either side of the engine isn't a problem.

I have seen a few people recommend all the charging sources be placed on the house bank size. I assume this includes the engine alternator. Although I like the idea of the alternator going straight to the larger house bank, I am worried this could end up killing my alternator if I have the "start" battery witch on, crank the engine, but have the "house" battery switch off. With the alternator going to the House side I wont start the engine (in normal use) without the battery switch on. Thought, If I have the charging bus connected to the ACR which connects to the "on" starter battery side will this provide me cover so as not to kill my alternator? Is this a reliable option to depend on the ACR to close the Circuit when I start the engine? Am I wrong or does the ACR SI disconnect the battery during cranking and is this disconnect long enough to kill the alternator? I think I see what the point is of having all the charging on the House bus but I am still a little concerned about killing the alternator so some more input is appreciated.
As long as the alternator is wired directly to the house bank with a fuse the switch has no effect on its output. Neither does the ACR. The ACR's start isolation is designed to open the ACR during cranking. This will not damage the alternator as it is wired directly to the house bank.
The alternator cannot be damaged if it is connected to a battery.

Another area I would like to draw attention to is the AC common ground and where it connects to my DC negative bus. Everything I have read says this is correct to have one point where the AC ground connects to the DC negative but it still seems odd. Does this not energize all of my AC ground with DC negative? For devices with a case ground does this mean that if I happen to brush a DC positive wire against the case I will complete the circuit? Im sure I simple dont understand something but even though I have read this is correct several places I still dont feel great about it.

The connection between the AC ground (green wire) and the DC negative bus bis there for safety. It does not energize the AC ground. Current does not flow in the AC ground wire unless there is a fault. As far as case grounded items (chargers and inverters)
the case ground goes to DC negative. There is a possibility of completing the circuit if a DC positive contacts a metal case, just like there is if a DC positive contacts the engine which is also connected to DC negative.

[Intotheworld]

So I spent some of this weekend on the boat measuring and pulling out old wires (i tie some string around the end so that I can use the string to pull new wires). On the side I was planning to put the house bank I can only fit 300ah worth of batteries. Based on my planned usage I was really wanting to have around 400ah. So I read a lot more forum post and consulted with my trusty Boat Owner's Mechanical and Electrical Manual and am leaning towards dividing up my house loads into a house bank that is dedicated to the inverter, refrigeration, and pumps (300ah), and one bank that is dedicated to electronics and lights (200ah), I would then have a reserve bank (80-100ah).

This will allow me to increase my battery bank size within existing spaces and not compromise m access to the engine compartment for maintenance. I already have 5 battery switches on the boat from the previous owner so these can be set up to allow any of the three banks to independently start the engine or power any of the house loads. I know 5 switches sounds complicated but in practice the house bank with the electronics and lights is on the starter switch and it would only be in a catastrophic failure situation that I would crank and run the engine without lights or electronics. The 2 house banks would remain separated taking care of their individual loads with the ACR between the to join them for charging. Each bank will also be closer to the distribution panel for its loads which should reduce the length and size of some of the battery cables I will need to run.

As for just wiring the 2 banks together, I am mostly concerned about the inverter/charger. I had to use 4/0 wire to connect it to the current house bank which is only a few feet away (12ft round trip for wires). The maximum the manual recommends is 30ft (round trip) which I dont think I can do.

I know that in an ideal set up I would have a large house bank and a small starter bank simply for redundancy. However since I can not seem to get to the house bank size I want within one bank this seems like a sensible solution that still provides plenty of redundancy.

I updated my wiring diagram to reflect this update, let me know what you think.
https://plus.google.com/photos/photo...POjzezi8Ny0jgE

[mitiempo]

The only difference between 1 house bank and 2 house banks is wire. One large house bank is better than 2 smaller ones for several reasons.

Look at installing golf cart batteries if possible.

I had no problem installing 4 golf carts (480 AH) on a 27' boat.

One large house bank - possibly in 2 locations - and a separate start battery with 2 simple on/off switches and an emergency switch is ideal.

[Stu Jackson]

Originally Posted by Intotheworld

>>>>>>>>>>>>>>and am leaning towards dividing up my house loads into a house bank that is dedicated to the inverter, refrigeration, and pumps (300ah), and one bank that is dedicated to electronics and lights (200ah), I would then have a reserve bank (80-100ah).>>>>>>>>>>>>>>>>>>>>>>

This is so wrong in so many ways that it appears you haven't read what Maine Sail and Nigel have been writing for the past two decades.

The LARGEST house bank is better. Just wire across the boat, not an issue. Size your wiring to avoid electrical drop outs. If you want, switch so that you always start the engine on the reserve bank, and use the house for all other loads including electronics. Separating a house bank for different uses has proven to be useless and complicated without good reason.

You might want to poke around here, it includes a lot of Maine Sail's material via link, and simplified wiring diagrams that have been proven to actually work. You are reinventing the wheel unnecessarily.

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

It includes a simple 1-2-B switch diagram as well as a three switch variety, with lots of text for explanations. Switch your AO for ONLY a service disconnect fuse, otherwise leave that switch ON. Or don't switch it and remove the fuse for service times.

Good luck.