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Old 09-18-2019, 12:42 PM
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Aj@yknot Aj@yknot is offline
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Red face Engine room and House side

I've got the wiring catalog for my current *engine room* setup, and I have some items I'm going to be adding to the engine connectins (tach/vacuum/waterflow/fuel pressure) that I need to acquire over the next little while. Boat should be coming out on the hard in mid october and my projects will engage then. There are *tons* of good reading in this forum on electrical issues, and I've read quite a number of them.
I'm trying valiantly to understand the different methods of keeping a *house bank* charged. Currently (pun intended) *as far as I know at the moment* my boat has 2 batteries on board and they are both being topped off my the shore power connection through a (charger/inverter) that doesn't seem likely to do anything else at all. I have two 110v AC plugs on the boat but have not managed to chase down the wiring path for those and (at the moment) have this sinking feeling in the pit of my stomach that there is *no* AC breaker anywhere other than the one on the pier. (the item labelled 110v MASTER breaker does nothing and has no connections at this time.)

I would *like* to consider the following:
a) properly protect the 110v circuits on the boat with a breaker. I'm guessing that the amperage of that breaker should be appropriate to the *charging* side as well as the individual 110v curcuits having breakers appropriate to the usecase of the endpoint.

b) adding a new "engine" battery and moving the two current batteries to 'house duty'

c) I get the impression that to do this properly and ensure that all batteries get charged appropriately one needs a device that manages input power (from alternator/shore/solar/wind) and handles each battery target based on its cycle/duty state. I rather expect that it will be complex to install correctly and cost a small fortune. But if I want to go down hte long path I may need that facility.

d) I see a lot of commentary about not spinning the battery selector through OFF while the engine is running. I've not touched the red dial battery selector on my boat. I suspect that I should remove/disconnect both of the batteries before I even consider that as at this moment, I only see *one* wire connected to the battery selector switch, and because I've not gotten deep enough in that space I'm not sure what that connects to. (under stbd settee, by the 'chart table' station)

e) for a 28' day cruiser that can potentially sleep 6, does not have (at this moment) a stove/oven but does have an icebox and a BBQ and a hotplate, *is it worth* considering an inverter to pull power off the house bank in DC and convert it to AC?

f) if I can lay my hands on the 3 80w semi-flexible solar panels that I *technically* have space for over the transom, given that I draw up the rest of the electricals, is it possible that someone here could advise on how to connect them most effectively?

I do have pics, sadly at this moment, the sd card they are on is drying out after going for a swim this weekend (my own stupidity) and I will put them in my gallery and link them to appropriate posts.
yKnot 28' Newport C&C @ PWM
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Old 09-18-2019, 06:53 PM
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Marian Claire Marian Claire is offline
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This is not my strong suit. But based on what I have on the MC.
a. Think about using a GFCI receptacle immediately after the breaker. Then feed all other receptacles from there.
b. That is how I have the MC set up. Wire the two "house" batteries in parallel. Selector switch 1 is "house' 2 is "start".
c. Based on the assumption that all batteries are the same type, size and age/usage. Your 1/both/2/off selector switch will do what you need. Each charging option should have its on control.
e. I have a small, 150 watt, inverter to charge my lap top etc. I would not want to use 12V to cook.
f. May be more than you need. Charging systems need to be sized with the battery bank.
Others will have more info.
S/V Marian Claire
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Old 09-18-2019, 07:25 PM
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Al Schober Al Schober is offline
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Updating wiring & circuits is a good thing. But, it's more complicated than wiring a house (unless perhaps you have a generator and solar panels).
Shore power breaker should indicate reverse polarity. Needs to be close to the shore power connection (6' as I recall) and sized to protect the downstream AC wiring to your AC panel. Smaller breakers in the AC panel will protect downstream wiring from there. For the AC outlets, I'd put the GFCI outlet after the AC panel and it's breaker.
I got rid of my A/B switches and used an on/off switch on each bank - less confusion. Alternator output went directly to the house bank. Charger/solar should probably do the same. When the house bank came up to voltage (13.5?) a relay closed and sent charge current to the engine battery.
For a computer, you may need a full sine wave inverter.
Don't wire it so you can run the battery charger off the inverter! Actually, the wiring (panels and selector switches) should prevent anyone from doing things wrong - it's not something you should have to remember!
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Old 09-19-2019, 12:03 AM
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ndutton ndutton is offline
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I suggest you'll be better off starting from scratch with a new wiring system rather than tracing down whatever sins of the past (factory or previous owners) might still be aboard. As you develop your new system, consider that it is you who will be doing the troubleshooting and repair. You want to end up with a system tailored to your abilities, that you understand.

Here are a couple of threads on the DC side of things you may find interesting:
starting at post #19
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
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Old 09-19-2019, 08:30 AM
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msmith10 msmith10 is offline
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Adding to Al and Neil's posts:
No idea what your boat is like or your capabilities but:
If you don't understand basic AC wiring, buy a copy of Richter ($15 at Lowes or HD). It is not about marine wiring- it's for residential/commercial wiring but it's the simplest and most useful book to learn the basics and you can learn the variations needed for a boat after that. Nigel Calder book "Boatowners Mechanical and Electrical Manual" will answer a lot of questions about everything and should be on every boat.
It's very possible your AC wiring is solid copper. Even if it's not, easiest and safest to rip it all out and start over. Then you'll know and trust your system. Use only braided/tinned marine cable. No wire nuts should ever go on the boat anywhere. Get a set of ratcheting crimpers- you'll use them a lot. A good set is $125 but a passable set is $25 on Amazon. Use adhesive lined heat shrink connectors.
Add a GFCI after the main breaker then branch that to your outlets as Dan said.
You can get a very cheap (< $10) reverse polarity indicator at almost any hardware store- I got a plug in unit sold as an outlet tester. I leave it plugged into an outlet in the cabin and check it as soon as I've connected to shore power. It shows a set of idiot lights that indicate if the incoming circuit was wired correctly.
Renewing the wiring on your boat isn't showy but it will really be one of the most satisfying jobs you'll do. And it's much more pleasant than replacing the head.
Mark Smith
1977 c&c30 Mk1 hailing from Port Clinton, Ohio
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Old 09-19-2019, 09:33 AM
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GregH GregH is online now
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Regarding your solar, I don't know what you know, or what your system is but if starting from scratch with some assumptions

- Are you wanting to be able to have the system recharged every day?
- Have your batteries recharged during the week while the boat sits at dock?
- Have your system last longer for a long weekend knowing you'll be motoring or running the engine in a few days to recharge?

Do up a 24 hr power budget of your DC. What do you use in a given 24 hour period on avg ( as sailing for a day and sitting anchored for a day typically will have differences)

2/ What is your house bank capacity in Amp-hours. Taking 50% DOC as your limit, can your bank handle what you want to do in a 24hr period.

3/ knowing the above, then you have to match your solar to the system and what you want to do. And use an MPPT controller to maximize your Amp input.
- For your 3- 80W panels, I'm making an assumption for the sake of example, they are rated at 20V each; when wired in parallel would give a potential output of 12Amps. Now in reality expect a good 20% less in capability from solar panels.
- So let's say 10A available form the panels at peak sunlight times, with your MPPT controller, it theoretically can boost that 10A to 16A (since W=VxA, taking 20V, 10A input and converting it to 12V, therefore 16A to get the same wattage) but reality may get up to 35% boost maximum.
- Will 13.3A during say 4hrs peak sunlight replace most of what the battery used in the previous 24hr period plus what is being used during the day (the off-peak times i'm assuming will be enough to top up that last bit of capacity )
- if it won't be enough power then you will have to look at either upping the solar wattage, or cutting back/changing power usage, etc. If you are looking to simply extend the number of days out, then with your 24hr usage and only partial recharge, will it extend your time as much as you want?

There are a few other smaller considerations to think about but I think I've rambled on here long enough.
1975 Alberg 30
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Old 09-19-2019, 10:11 AM
Dave Neptune Dave Neptune is offline
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I'd seriously consider going to a counter top stove instead of the hot plate. The stove will be cheaper than adding enough battery and solar to feed just the hot plate.
I have solar on my boat for the fridge and it keeps up nicely on sunny days and hits "float" by noon. On cloudy days it takes most of the day and still keeps up with the fridge, radios and lighting.
Converting to AC and cooking, Mr Coffee or a microwave really draw a lot of power when in use.
I have a friend who has a bigger boat and put solar all over because mine worked so nice and he still has "low" batteries quite often (4 X 4D's). He was perplexed and bribed me with a few beers to take a look. We'll the problem was he (his wife) uses the microwave a lot, her hair dryer daily, a large electric coffee maker, water heater and even an electric can opener as well as charging laptops and phones. When I explained how much he was using compared to what he could get from his two solar arrays, one at 400 and another at 360 I think. Anyway we took a long look at what the trouble was with his gen set and fixed it instead of adding more solar.
Solar is great but be sure it suits your actual needs.

Dave Neptune
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Old 09-19-2019, 10:44 AM
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First step is this book!

Read it while on your boat looking at what you have got. In my case a simple upgrade turned out to be a total rewire job.
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