Electrical Layout Advice / Opinions Required

[simonmd]

When I get my new boat (30ft Catalac 900) down here in the next few weeks, i'll have quite a bit of electrical fitting out to do to make her suitable for long term cruising / liveaboard.

At present, she only had 12v dc on board so i'll be adding a full 'mains' system using a combination of shore power, generator and inverter. What i'd like idealy, is a fully switchable system so I don't need to double up on power sockets. Both generator and the seperate battery fed inverters are pure sine wave so I don't forsee any problems but would like your opinions as to layout, etc.

[GordMay]

See ➥http://www.cruisersforum.com/forums/...itch-1960.html

And ➥ http://bluesea.com/files/resources/a...b%20Panels.pdf

[osirissail]

Your block diagram is normal standard European switching for what you described. It simply allows you to choose between Shore Power or Generator or Inverter for your power source.
- - The question arises that your block diagram shows a "battery Charger" - Is there one currently installed in the boat?
- - You mentioned that the boat "only had 12VDC on board." That would indicate that charging the batteries can only be by the engine alternator.
- - Since you are proposing to install a AC shore power/generator system, the question comes up to where do you plan to sail/cruise/use the boat? Remember that there are two different versions worldwide of AC power. North and South America use 120VAC 60 Hz (cycle) electricity while the rest of the world uses 220VAC 50 Hz (cycle) electricity.
- - I would suggest that you choose a battery charger that can utilize both systems. There are new battery chargers that will automatically accept either type of AC power. And make sure the battery charge is large and can supply a lot of DC amperes. Your inverter is going to be supplying the boat's AC power needs when you are in the "other" power supply region of the world and you will be using the battery charger to replenish the batteries.
- - Providing for this option means having an alternate switching arrangement to not allow selection of "Shore Power" to the boat's wiring when you are in the "other" AC power region - but - allows shore power to feed only the battery charger.
- - In essence it would consist of another switch that would enable shore power to power the "all-power systems" battery charger and at the same time disconnect the shore power feed to your master selector switch.

[skipmac]

If you use a Victron inverter you can connect it in parallel to the shore power and/or generator AC supply to use it as a power booster to augment the available AC power and would only need a two way AC selector switch. That's how I'm setting up my system. Allows you to use a smaller generator but still have enough power to handle the high start loads of compressors and such.

[simonmd]

Osirissail, yes, the boat is presently charged by engines and a suplimentry solar panel to keep it topped up. I have already bought a mains powered battery charger,
Sterling 12V 20 Amp Battery Charger - Only £214.95 - Force 4 Chandlery

which as you can see, does feature automatic switchover from 110 to 220vac so if I do goto a 110v port, i'll be able to charge from shore and run off inverter.

[simonmd]

Originally Posted by GordMay

See ➥http://www.cruisersforum.com/forums/...itch-1960.html

And ➥ http://bluesea.com/files/resources/a...b%20Panels.pdf

Interesting Gord, I note in the thread however that you don't think they're worth it,

Originally Posted by GordMay

I wouldn’t normally recommend Auto Transfer Switches for boats. I don’t think that the seamless transfer of source power is necessary, in most cruising applications.
I suppose I'm just a twentieth century guy, in a twenty-first century world - I'd stick to the KISS principle and switch manually.
Gord

I aggree with your view about KISS and have already bought a purpose made 32amp 3 way switch to do the job.

[osirissail]

How large is your battery bank(s) - amphours? And how much AC power do you anticipate using inside the boat?
- - A battery charger that puts out 12VDC and only 20 amps is extremely small and won't charge batteries much larger than 80 amp-hours total.
- - The normal "small" battery charger over on this side of the ocean is about 12VDC with 40 amps output.
- - But if you are putting in an inverter and a genset (generator) then I would guess you are going to be using a lot of AC power in the boat. That would suggest that you are going to need a large amp-hour battery bank(s) to power the inverter.

[simonmd]

I don't intend to use alot of AC power no, hot water and cooking is gas for example, I just simply want it available no matter what. So, whether on shore or at anchor, or at sea, i'll have some juice available.

I was reccomended the 20amp as its not the sole charger on board. In fact, it's more of a backup as I intend to be on the hook more often than not. The boat will also have a sizable solar array, about 400w and a decent wind and tow genset. Therefore, it'll only be used to topup when at a marina and in conjunction with the generator when needed.

[osirissail]

Remember that the Generator is AC voltage (unless you are planning to purchase a 12VDC generator). It will be using the shore power battery charger to refill (charge) the batteries.
- - Inverters use 12VDC in large amounts - more than 10 to 1 for conversion the 120VAC and probably 20 to 1 for 220VAC. That is, for 1 amp of 220VAC you will suck 20 amps or more from the batteries. For a coffee maker or TV or computer you can easily consume some serious amperes from the batteries.
- - Normally the cost difference between the 12VDC - 20 amp output battery charger and the 40 amp output is very small.
- - Recharging your batteries up to "full" takes a varying amount of output from the battery charger. Oh! be sure the shore power battery charge is the new "smart" or computer controlled multi-step battery charger. Do not get an automobile type battery charger!
- - A "smart" battery charger will supply a high amount of amperes into the batteries to start the recharging and then reduce the amount of amperes it feeds to the batteries in - usually - two more steps. Typically you will see the three step "smart" chargers use words like: "Bulk charging - Absorption Charge - Maintenance Charge" or words similar to those to describe the 3 different steps in recharging the batteries.
- - Depending upon the "type" of batteries that will be installed in the boat - normal "liquid lead acid" or "AGM - absorbed Glass Mat" or "Gel" or the new "Lithium" - it is critical that your shore power battery charger - and - your engine alternator regulator have the ability to properly recharge the particular battery type. Batteries are very expensive and using the wrong process to recharge them can quickly lead to significant decreases in the battery's life.
- - Depending upon where in the world you will be using the boat, solar and wind power systems vary considerably in the amount of electrical power you get from them.
- - If you look at the electrical threads on CF you will see that Solar Panels only produce sufficient electrical power during 4 or 5 hours per day and in cloudless skies.
- - Likewise, Wind generators need significant wind - like the tradewinds in the eastern Caribbean - to generate any usable electrical power to recharge batteries. And - cruisers tend to anchor in areas with low winds for comfort in the boat. Wind generators need a lot of wind to put out significant power.
- - Towing electrical generators are a great idea - but - you have to set them up while sailing and then convert them back to wind after sailing. There is a tendency to just not want to do all that work so they are rarely used as towing generators. Beside which, anything you "tow" that is attached to the boat will slow the boat down unless you are sailing in high wind conditions.
- - All these things make up the "difference" between what the brochures and salesmen tell you and "real life" on a cruising boat. You will learn with time and experience that a lot of the brochures and salesman's information is quite different from "real life."