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36 luhrs convertable

Discussion in 'Luhrs Yacht' started by domenicis, Apr 21, 2020.

  1. domenicis

    domenicis New Member

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    My frig only works on 12 volts i am sure it is original it should run on 120 volts when plug ed in but does not Is there a fix or replace frig works good on battery but does run it down even with the charger on shore power any thoughts
  2. NYCAP123

    NYCAP123 Senior Member

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  3. Capt J

    Capt J Senior Member

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    The converter for the refrigerator is bad. If you leave your battery charger on, then it shouldn't be a problem to run the refrigerator off of 12 volts. If you lose shorepower it will cause your batteries to go dead faster. WHY would the refrigerator run the batteries down with the battery charger on? The battery charger should be sized large enough to run the refrigerator off of it. What battery charger is installed in your boat? Make/model.
  4. mapism

    mapism Senior Member

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    Seconded.
    I'd be more concerned about the charger than the fridge, if it can't keep up with the current demand of the fridge and also have a fair amount of additional charging capacity on top.

    PS: R U sure that the fridge is connected to BOTH DC and AC?
    I don't mean to offend or anything, I've actually seen a boat which came from the builder with just the DC connected....
  5. domenicis

    domenicis New Member

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    I am going to pull the frig out and check behind to see if there is something easy like a blown fuse.
  6. domenicis

    domenicis New Member

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    My boat is a 2000 and i believe the charger and the frig are original. I am going to look deeper into both.
  7. NYCAP123

    NYCAP123 Senior Member

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    This is what I was alluding to with the link. If the OP isn't leaving his charger on it's designed to run off the batteries. This is why batteries should always be turned off when leaving the boat, and the charger left on:
    "we are now blessed to have marine fridges utilizing the super-efficient Secop (formally Danfoss) compressors that are powered by 12v or 24v DC. Under normal circumstances, when the vessel is at the dock and plugged in to shore power, the battery charger will be on and supplying the DC power for the fridge. The batteries are not involved in this process, as the DC from the charger does not go into and out of the batteries, but is supplied directly to the fridge from the charger."
  8. mapism

    mapism Senior Member

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    I'm not sure to see what you mean, NYCAP.
    While the boat is docked, connected to shore power and with the charger on, don't you leave the domestic battery bank connected?
    I mean, don't you need DC also for lights, toilets, fresh water pump, whatever?
    DC-powered fridges shouldn't run down the battery bank anyhow, as long as the battery charger can supply more amps than all the DC equipment can demand, which should be a given.
    In fact, I also don't get the point in that CCC webpage:
    "the DC from the charger does not go into and out of the batteries, but is supplied directly to the fridge from the charger".
    I mean, isn't that's stating the obvious, and always true regardless of whether the batteries are also connected or not?
    Last edited: Apr 21, 2020
  9. cleanslate

    cleanslate Senior Member

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    You always need DC battery power for your bilge pumps PERIOD while the boat is in the water . In the event of any type of emergency such as a busted hose or busted seacock or whatever.
    Which tend to break while you are not around .
    Never switch off your DC power or disconnect from your batteries and always keep your charger on to keep the batteries up to full charge in case the bilge pumps have to run for a long period of time in an emergency.

    perhaps there’s a wiring diagram somewhere on or in the refrigerator or on the back of the unit but it sounds like something broke with the unit.
    finding a fuse that sounds like a good idea I bet you there’s one in there somewhere.

    Good luck !
  10. NYCAP123

    NYCAP123 Senior Member

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    On smaller boats I always shut the batteries as I leave to prevent an errant draw from the fridge, lights left on, etc. Easy enough to flip it on when I re-board. Now I'm no electrician, but I learned (as the article states) that the fridge gets it DC charge from the charger, not the battery. It goes to ac when on the gen. If the shore power gets cut the fridge is going to draw off the battery if it's left on. A fridge will definitely suck the juice from a 12v battery in short order. My guess is that either you didn't leave your charger on or there's a problem with it.
  11. NYCAP123

    NYCAP123 Senior Member

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    Your bilge pumps should be direct wired, not controlled by the battery switch.
  12. mapism

    mapism Senior Member

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    Yes it does, but that's what actually happens also when the fridge is connected to the batteries.
    Just think of a normal scenario, where the battery bank is fully charged and connected, with the charger on.
    In this condition, the charger supplies just a few amps in floating mode, because it automatically senses that it only takes a tiny bit of current to keep the batteries topped.
    In this scenario, if you turn on any DC component that demands some current (by the way, a fridge is very far from being one the most demanding components - let's say for instance that you turn on a bow thruster that draws 40 Amps), the charger immediately senses the current demand, and instantly spikes up the supply to cope with it.
    Therefore, for all intent and purposes, it's always the charger (when it's turned on, obviously) that copes with any DC demand, and that remains true also if the battery bank is connected.
    Current is drawn from the battery bank only if and when the DC current demand should exceed the charger capacity.
    Other than that, the current just flows directly from the charger to the fridges/thruster/pump/you name it, also while the battery bank is connected.

    That said, I agree that if you leave the boat unattended and you know that you don't need to leave on any DC equipment, you can as well shut the battery bank off.
    But it's pointless to bypass the battery shutdown for a fridge: if you need to leave it on, just leave the batteries connected, and you achieve the same result. In fact, most modern nautical fridges are DC only, because the AC conversion is just another useless bit that can go wrong.
    Aside from superyachts designed to run on 3-phase AC 24/7 of course, but that's another league altogether.

    The only exception to this general rule are bilge pumps, which indeed should bypass the general battery disconnector, as you are saying.
    In this respect, I also disagree with cleanslate.
    In a well designed electrical system, it should be possible to disconnect DC completely, fridges included, because that makes sense when the boat is left unattended for some time, and there's no need to keep anything on, including DC cameras or other remote control systems - if any.
    But, and it's a BIG but, each bilge pump RCD should always be directly feeded by the battery bank (hence also by the charger), bypassing the general disconnector.
    Last edited: Apr 21, 2020
  13. NYCAP123

    NYCAP123 Senior Member

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    Exactly.
  14. cleanslate

    cleanslate Senior Member

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    Nope they are on a Circuit breaker in the panel. If battery switch is off no power to the panel , no pumps .
  15. NYCAP123

    NYCAP123 Senior Member

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    I'd be surprised if that wasn't the sump, water or macerator pump or it's a manual override switch to manually turn the pump on. Otherwise it would beg the question when would you want the bilge pump turned off? There's no fear of accidently leaving a bilge pump on, and that breaker would present an unnecessary fail point.
    Last edited: Apr 22, 2020
  16. mapism

    mapism Senior Member

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    Well, actually the breaker still makes sense.
    It's supposed to be there to protect the circuit, otherwise in case of overload there is a risk of melting the wires insulation and potentially spark a fire.
    Also, nothing wrong with having the breaker in the same panel as all others.
    That's where they are also in my boat, and I've seen the same arrangement in many others.
    What is definitely wrong in the setup that cleanslate mentions is that these breakers should be directly connected to the battery bank, as the charger also is, bypassing the general battery disconnector.
    Btw, I notice that I wrote "RCD" at the end of my post #12 when talking of this electrical scheme.
    My mistake: replace that with "breaker" instead.
  17. chesapeake46

    chesapeake46 Senior Member

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    On my little baby, the bilge pump does have a breaker in the same panel as the rest of the the DC breakers BUT, it is fed from a hot feed & separate wire, fused near the battery and fed on the line side of the breaker from that fuse.
    Not from the DC buss that is fed from the battery switch ( which feeds the DC buss.).
    When the battery switch is in the OFF position, the bilge pump breaker is still hot on the line and load side.
    Mine has the bilge breaker at the very top of the DC breaker stack.
    I would imagine it would be at the very top or very bottom of the breaker stack to be separate from the DC buss.
  18. domenicis

    domenicis New Member

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  19. cleanslate

    cleanslate Senior Member

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    There you go ! Just do it and try not to overthink the situation which were all guilty of from time to time... Except me!
    Lol!

    now hope it doesn’t blow again after putting a fuse in... Then you have other problems like a bad compressor or such.
    But let’s be positive I’m sure that’s not the case good luck.
  20. Rich Plukas

    Rich Plukas New Member

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    Great discussion though, appreciate all the good input.