House battery bank choices

Discussion in 'OnBoard Electronics & Controls' started by GoSlow, Aug 6, 2008.

  1. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    Fast Fred,

    Sorry mate, no i did mean the flue of the fridge itself, my understanding was always they had to be vertical or the flue does not work correctly, happy to be proven wrong, but that sounds logical to me too.
     
  2. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    That's not quite what Landlubber means.
    Gas powered fridges work on the dissolving and evacuation of NH3 in water, where the fluid levels in the 2 chambers are very critical. The movement of vehicles or boats further deteriorates the (already poor) efficiency of such a cooling system.
    It is still in use for low cost fridges and was in fact the only way to cool before the compressor fridge was invented., but energy consumption is at least 5 times higher.
     
  3. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    The fridges with the Danfoss motors are brilliant, low power (2.5 - 3A) 12V and actually works. Keep in mind they don't run all the time so they are economical.
     
  4. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The movement of vehicles or boats further deteriorates the (already poor) efficiency of such a cooling system.

    Sorry but for a motorboat you have it exactally wrong.

    Healing at a large angle today that is over 15deg , does slow the cooling and does cost slightly higher fuel use.

    But the mostly upright motion actually HELPS the cooling as it causes the coolant to circulate better.

    An exhaust flue is required to keep the cabin cool for folks with a small cabin in a tropical area. RV.s use them with great sucess, but the home folks with a larger volume , dont notice extra heat in the home.

    A flue ventilation for the exhaust would be a good idea on a boat because the extra moisture might condense in an unventilated locker or similar area.

    "(already poor) efficiency of such a cooling system."

    The modern units , however "inefficient" that use 1/4 to 1/2 lb of propane a day silently are far easier to live with than DC , a thousand? pounds of batterys, a noisemaker demanding to operate frequently , and a computer controlled freon package.

    No question that IF there is room for 3 or 4 75W solar panels the DC is a rational choice , but may require the noisemaker for weeks on end , depending.



    FF
     
  5. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    In my boat we have a small Waeco stainless steel fridge with compressor cooling. In summer it needs ONE 50 watt Siemens solar panel. It is silent, makes ice cubes and can keep frozen stuff during the night.
    Most fridges in this area are propane powered. I see people carrying around gas bottles once a week. When moored on a quiet day, the owners dance when there is a little bit of ice forming, but as soon as they start rocking the boat the ice is gone again.....

    But I do admit that for the price of one good compressor fridge you can buy 3 propane ones.
     
  6. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    For folks with very limited energy the "old" way of building a top loading box , and insulating it with 6 inches of the best insulation is the answer.

    Weather the energy is better drained from a battery, or from a coldplate will mostly depend on the vessels style of operation.

    We have a motor sailer that has an engine driven auto auto cond pump (cast iron York) feeding 2 coldplates. One in the fridge , one in the freezer section.

    The plates are over sized (so take up a good bit of box volume) but we keep 5F for 4 days. Inshore cruising we simply change harbors every 3 days , for our summer cruises. Ice cream is no problem for months.

    It works out well, but since harbors are close in New England , the sails don't see much use. This can be done on any cruiser , the main requirement is foe enough SPACE for a box with 6 inch insulation , and the plates.

    The virtue of propane is the cruiser can go months with frozen food and no noisemaker requirements.

    A Servelle is about $1300 , a water cooled DEC modern compressor setup is about $800, for your box.

    Cold plate can be DC or mechanical compressor powered .

    Tiny DC store boxes are fine for the day sailor , but hardly useful for a cruising boat that may want months of supplies frozen.

    FF
     
  7. TollyWally
    Joined: Mar 2005
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    Location: Fox Island

    TollyWally Senior Member

    Attached Files:

  8. GoSlow
    Joined: Apr 2007
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    Location: USA

    GoSlow Junior Member

    Many thanks for the information.
     
  9. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    http://www.powerwerx.com/product.asp...D=34676&CtgID=

    All the units I'm familiar with use a shunt that costs more than this setup.

    IF,,, it will handle the MAZ amp charge rate from your on board charging ,
    and the MAX discharge rate from onboard users combined , I guess its a solution.

    Do let us know , it sure is cheaper than the real marine units.

    FF
     

  10. TollyWally
    Joined: Mar 2005
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    Location: Fox Island

    TollyWally Senior Member

    Certainly I will post a report. With any luck it should arrive in the next week, it will probably take a few days to get it installed.

    I just installed a fresh new set of 4D batteries and have lusted over the more conventional meters. I have high hopes for this little unit but we shall see. In the end, it is what it is; regardless of advertisng claims! :)
     
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