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Thread: Ship-to-shore power

  1. #1

    Default Ship-to-shore power

    I'm sure this will seem like a no-brainer to you folks familiar with ship-to-shore power but it is new to me and I have some basic questions.
    I have a SeaSport Explorer. Do I turn off my battery power before connecting to AC power? Will AC power connection enable me to use bilge pump and on board DC stove? What is this about reverse polarity? Any advice appreciated.

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    ?? I have a SeaSport Explorer. Do I turn off my battery power before connecting to AC power?

    I do not know why you would need to.

    ?? Will AC power connection enable me to use bilge pump and on board DC stove?

    That all depends on how you have every thing wire up. DC stove?


    ?? What is this about reverse polarity?

    AC doesn’t have polarity, I think there talking about the battery charger. Do you have a built in battery charger or you adding one?

    It would help if you gave us more information on your SeaSport.

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    Quote Originally Posted by leveen View Post
    I'm sure this will seem like a no-brainer to you folks familiar with ship-to-shore power but it is new to me and I have some basic questions.
    I have a SeaSport Explorer. Do I turn off my battery power before connecting to AC power? Will AC power connection enable me to use bilge pump and on board DC stove? What is this about reverse polarity? Any advice appreciated.
    No you do not have to turn off your batteries before connecting to AC as they are totally different circuits.

    Your bilge pump and any other items that run on DC power wil continue to do so as long as your DC power master switch remains in the on position. Your battery charger, if equipped, will continue to charge your batteries while connected to AC power.

    On my boat when I connect to AC power the power panel shows that I have a proper connection to AC power. Having reversed polarity causes an increase in galvanic corrosion of your metal parts.

    RM,
    AC does have polarity and hence the reason many plugs that now come with one tang a little larger then the other. Also the reason GFI's work.

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    2 different configurations, depending on what you want

    1. If you have or want AC power on your boat your best bet is called a inverter/charger, it hooks up to your batteries and to a AC source like shore or a generator, when a AC source is applied it transfers any onboard AC load to it while its charging the batteries. A inverter/charger may only handle 1 bank of batteries.
    -- An alternate and less expensive config is you have a separate AC driven battery charger and a battery driven inverter.
    It costs more but a true sine wave inverter is best for onboard usage like a microwave or TV. Just make sure the inverter can handle a charging current being applied to the batteries; most can but make sure. (this is the route I took)

    Since your charger will be near your batteries make sure its ignition protected and marine rated. Batteries outgas hydrogen when charging, a buildup could lead to a big boom!

    2. If all you want is shore/generator power to charge your batteries a marine rated/ignition protected charger is what you want, its pretty easy to find chargers that handle multiple banks.

    Deep cycle battery banks charge best at the C/8 rating. Which means to find the amperage you want for your battery charger take your battery banks Amp-Hour rating and divide it by 8. That'll give you the optimum charging rate, you can go lower than that amperage, but its not good for battery longevity go higher than your C/8 rate. Keep in mind this is only for true deep cycle batteries like trojan L16s - starting/deep cycle batteries can take a lot more charging amperage - but they dont last as long.
    2696 Sea Raider Pilothouse
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    Having reversed polarity causes an increase in galvanic corrosion of your metal parts.

    RM,
    AC does have polarity and hence the reason many plugs that now come with one tang a little larger then the other. Also the reason GFI's work.[/QUOTE]




    I do not want to hijack the thread, I do think I need to say something.

    Because the AC is switching between + and – the same amount there is no increase in galvanic corrosion because sum of the current is zero. That is why AC does not increase galvanic corrosion.

    AC stands for Alternating Current the voltage/current alternates between + and -, there for it does not have a polarity. If you took a AC vom and measure between the hot and neutral, reverse the leads it would read the same voltage.

    Yes you do need a properly wire connector for the GFI to work, because of the design of the GFI not because AC has a polarity.

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    There might be a little confusion here, RM is correct as far as AC is concerned, however if you connect your third prong AC ground to the hull THEN you have problems, BIG problems.

    DONT connect the AC ground wire to the hull, on a boat (and only on a boat) its best to have a floating ground, the inverter will have an internal ground for the 3rd prong, I believe its attached to the negative DC lead from the battery, but I dont know for sure.

    Even without a direct connection to ground - the AC in the wires will induce a current in the ground line, if thats going to an aluminum hull you're going to get nasty galvanic corrision.

    If you DO have a connection of either leg to ground (and you'd be surprised how often it happens) then multiply everything I said above by an order of magnitude, and you now also have a bad safety problem.

    I'm an avionics guy and galvanic corrosion and 400hz AC power is something I have to deal with all the time.
    2696 Sea Raider Pilothouse
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    If you are using AC on a boat you must connect the AC ground to the boat ground and all the grounds go to a single grounding point to hull ground for safety reason.

    You are correct if you connect the AC ground to a boat it can increase your corrosion problems if you have any. In the boating world they recommend you use a Galvanic Isolator in the ground line, to give you ground protection and stop the ground from increasing the corrosion problem.

    Ship to shore power consist of 3 wires, Hot, neutral and ground, the neutral and the ground are connected together at the power box if you have stray AC current going to ground it the same as having a hi-resistance ground and can bypass the Galvanic Isolator if you have one. Some boats use an isolation transformer to solve this problem.

    Again this has nothing to do with the original questions.

  8. #8

    Default Technical but correct

    But back on the subject, I added 2 duplex recept, one in the cabin one waterproof one under the hood. I have one of those Potted or a Battery maintenance charger, which makes it Intrinsically Safe ( no arc spark) so if I want to charge while on the doc because I'm using the batterys for bildge, radio heat, I don't drain the battery. You bet you can spend more money than this!
    The point of arc spark will only come from when I disconnect the battery clits from the posts, but I always unplug the charger first.

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    Quote Originally Posted by alaskapiranha View Post
    But back on the subject, I added 2 duplex recept, one in the cabin one waterproof one under the hood. I have one of those Potted or a Battery maintenance charger, which makes it Intrinsically Safe ( no arc spark) so if I want to charge while on the doc because I'm using the batterys for bildge, radio heat, I don't drain the battery. You bet you can spend more money than this!
    The point of arc spark will only come from when I disconnect the battery clits from the posts, but I always unplug the charger first.
    Get a marine battery charger and do a hard wire install.

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