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    New Fridge Install, Questions on 12V power-gctid354889

    Soon I will be installing a new fridge to replace my non-functional one. I am on a tight budget this summer, so I may be getting a 12v super conductor model for under $200. I think the 12v wattage rating was somewhere near 83 watts. I'm still a newbie when it comes to electrical systems so I have a few questions:

    -If the fridge stays on for a long time (on the boat's 12v DC wiring) when the boat is on shore power,will this hurt the battery(ies)?

    -I want to be able to have an on/off switch that can turn the power off to the fridge for long storage durations (i.e. winter). How do I do this? Note that my fridge compartment currently has two loose 12v wires (red & black) that are always powered.

    -I may want to install one or two 12v computer fans as well to help improve circulation around the super conductor. I'd want this connected to the on/off switch as well.

    Do I need a terminal block, switch, relay, etc, etc? I'm so confused!

    Text Diagram: 12v DC power from boat (from existing fridge) -> On/Off Switch -> (Terminal block/switch/relay/etc???) -> 12v Fridge & 2 12v PC fans.

    Any help is much appreciated!

    UPDATE: I purchased an Isotherm Cruise CR 65 on March 18th instead of going the route above. See my last post.

    #2
    The 83W 'fridge will draw about 7A from the batteries. Plan on a continuous draw, if less it won't be much less during the heat of summer.

    Those existing always-powered 12V red / black wires HAVE to already be going through a switch / circuit breaker, unless the existing wiring is totally hacked-up.

    Provide plenty of free-air ventillation. Use additional 12V fans if required, but they will help to suck down the batteries. Put them on the same circuit as the 'fridge.

    Comment


      #3
      Thanks. 7Amps is a bit up there, considering the Norcold, Isotherm, etc. fridges are 3 or less. (Isotherm claims .6 amp average / 2.7 amp max for their 1.7CF CR49 12v DC model)I'm assuming I would do something like this, but instead of lights I would have a fridge and a couple of 12v PC fans?

      [img]/media/kunena/attachments/vb/657800=24960-LightingCircuit.jpg[/img]I'm assuming I need to be careful during days where I'm out all day, 10+ hours, and playing the stereo. I'm unsure of my house/deep cycle battery's amp hours but it's only a few years old. I have another crank battery which I use only for cranking of course.

      Comment


        #4
        What size are your batteries, group 27 or 31? How many banks? How many batteries per bank? Regular flooded cell batteries or AGM?

        Comment


          #5
          I have two batteries in total. One house and one crank... on a 1/2/off/both switch. To be honest I haven't removed the batteries from their covers since I purchased the boat back in September. I was planning on getting them tested and identified after dewinterization. Though, I had no issues with the house/deep cycle battery during the last few long 10+ hour summer days on the lake (with the stereo and a few 12v cellphone chargers on the whole time).

          Comment


            #6
            KnoxBoater wrote:
            I have two batteries in total. One house and one crank... on a 1/2/off/both switch.
            Here is the specification for a Group 27 flooded cell marine battery.

            It has 105 Ampere-hours capacity when discharged at the 20 hour rate. A 7A continuous draw would deplete a new fully-charged battery in 15 hours (105Ah / 7A = 15h). A battery loses capacity over time, usage and temperature. Ballpark the capacity dropping by 10% per year. A battery is typically considered end-of-life when the battery has 50% of the nameplate capacity remaining.

            The common solution for longer run time is to place several identical batteries in-parallel. They should even have the same date code for best results.


            Comment


              #7
              It sounds like this is an ammonia refrigerator, not a compressor/Freon type? If that's true, that explains the ridiculously high power usage. And it will run 80-100% of the time. They are really awful at cooling too.

              By comparison, when I upgraded from ammonia to a compressor fridge I went from 11 amps at 80-100% duty cycle to 3.2 amps at 20% duty cycle.

              As far as a switch, it doesn't have a thermostat with an "off" position?

              Comment


                #8
                WHOA! Wait, I just thought about that "superconductor" stuff and thought you might be talking about a Peltier thermo-electric cooler? Is that it? If so, you will HATE IT!! Don't do this. They are horribly ineffective. They normally produce about a 30 degree change in temperature, and around 40 max. So if it's 100 degrees on the exhaust side of the cooler, it will be 60-70 inside the fridge. Totally useless.

                BTW, there is no such thing as an actual superconductor fridge. Those terms don't go together.

                Comment


                  #9
                  KnoxBoater wrote:
                  Soon I will be installing a new fridge to replace my non-functional one. I am on a tight budget this summer, so I may be getting a 12v super conductor model for under $200. I think the 12v wattage rating was somewhere near 83 watts. I'm still a newbie when it comes to electrical systems so I have a few questions:

                  1.... -If the fridge stays on for a long time (on the boat's 12v DC wiring) when the boat is on shore power,will this hurt the battery(ies)?

                  2.... -I want to be able to have an on/off switch that can turn the power off to the fridge for long storage durations (i.e. winter). How do I do this? Note that my fridge compartment currently has two loose 12v wires (red & black) that are always powered.

                  3... -I may want to install one or two 12v computer fans as well to help improve circulation around the super conductor. I'd want this connected to the on/off switch as well.

                  4.... Do I need a terminal block, switch, relay, etc, etc? I'm so confused!

                  5.... Text Diagram: 12v DC power from boat (from existing fridge) -> On/Off Switch -> (Terminal block/switch/relay/etc???) -> 12v Fridge & 2 12v PC fans.
                  KnoxBoater wrote:
                  I have two batteries in total. One house and one crank... on a 1/2/off/both switch.
                  I doubt that these units work all that well for our marine needs. If Carlos is correct, they are power hungry, and you can't afford that kind of power unless you have a huge HLBB (house load batt bank) and a means of recharging it sooner than later.

                  According to the above quote, you have only two batteries on board.

                  I see you mention tight budget, but I'd hold off until you can purchase a true 2-way Marine compressor type refrigerator.

                  Your 2855 deserves a much larger HLBB and a true Marine Refrigerator, IMO.

                  I'd suggest using ice chests while saving your money.

                  1.... Not enough info in post #1.

                  You'll want an O/B smart charger. The charger will provide battery power while the frig is drawing from the battery.

                  With a 2-way Marine frig, this is a non-issue. It will default to 120 VAC when S/P is available, and will default to 12 vdc in the absence of S/P.

                  2.... That would be your breaker in your 12 VDC panel. Use it as your switch.

                  When you leave the boat unattended, all 12 VDC power will be cut via your MBSS.

                  I don't know what the two loose wires would be for.

                  3... With that type of frig, your 12 vdc demands will have increased even further. Way too much for a single HLBB.

                  Cooling fans like these are normally controlled to operate only when needed.

                  4.... Still think that you're going the wrong way here.

                  5.... Not quite following you here.

                  Once a refrigerator is powered, the internal thermostat controls the cycling.... be it the Super Conductor model, or a real Refrigerator.

                  If you must cycle the unit outside of the thermostat, then something is wrong.

                  .
                  Rick E. Gresham, Oregon
                  2850 Bounty Sedan Flybridge model
                  Twin 280 HP 5.7's w/ Closed Cooling
                  Volvo Penta DuoProp Drives
                  Kohler 4 CZ Gen Set

                  Comment


                    #10
                    Thanks for the well thought out responses. It sounds like Ill use coolers this summer and wait until this project is at the top of the priority list. Its hard to justify 800 bucks for a true 2 way marine fridge when I have so many other boat projects to do that will net more benefit.

                    Comment


                      #11
                      Doesn't need to be 2-way; a 12v only is fine. I had one in my previous boat. It just needs to have a compressor and Freon. Not ammonia, and not thermo-electric. A real compressor-based 12v mini fridge will only use 3-4 amps and run 20-25% of the time.

                      Comment


                        #12
                        I have the DE0051 norcold. 2.7 Cu ft. On DC it takes 2.5 amps compressor running, and 1/4A compressor off (fans and control board current)

                        It puts a lot less heat into the boat interior than the amponia one did that came with my 2452, and gets the inside a lot colder. On a 92* day, the inside was about 40*. Can't do that with amonia.

                        Batteries: read this:

                        http://www.baylinerownersclub.org/fo...s-and-Charging

                        Should answer you questions.

                        BTW, norcold has a shutoff on the temp control knob
                        Captharv 2001 2452
                        "When the draft of your boat exceeds the depth of water, you are aground"

                        Comment


                          #13
                          Its hard to justify 800 bucks for a true 2 way marine fridge when I have so many other boat projects to do that will net more benefit.
                          Perhaps not so much when you consider that you own a nice 2000 Bayliner Ciera 2855 that will better retain it's value when the proper equipment is used.

                          Once we begin using less than high quality replacements, it eventually becomes evident to a savvy "would-be" buyer.

                          Just a thought!

                          .
                          Rick E. Gresham, Oregon
                          2850 Bounty Sedan Flybridge model
                          Twin 280 HP 5.7's w/ Closed Cooling
                          Volvo Penta DuoProp Drives
                          Kohler 4 CZ Gen Set

                          Comment


                            #14
                            2850Bounty wrote:
                            Perhaps not so much when you consider that you own a nice 2000 Bayliner Ciera 2855 that will better retain it's value when the proper equipment is used.

                            Once we begin using less than high quality replacements, it eventually becomes evident to a savvy "would-be" buyer.

                            Just a thought!

                            .
                            Could not agree more. :arr I know if I saw a boat with a regular fridge and inverter install or some Canadian tire special I would definitely run from the sale. If you are too cheap or do not have enough budget to buy the proper unit, I can only imagine the neglect the rest of the boat has seen due to lack of funds. Sure there are exceptions but I sure as heck would not take the chance. The ice chest until funds are available is the route to go. This also gives you tons of time to come up with a fantastic deal or next years "Black Friday" super deal.
                            Cheers, Hans
                            2007 Carver 41 CMY
                            Twin Volvo D6-370
                            Montreal, Canada
                            Midnight Sun I Photos

                            Comment


                              #15
                              To the OP:

                              I am 65, a retired engineer and boater for over 40 years. Being you appear to be relatively a new boater, here's some advice which comes from the expieriences of myself and friends. I also made my living designing and masaging products to work in a specific environment.

                              Besides screwing up resale vale, shortcuts like what you propose usually wind up costing more in the longrun. There are many posts on this website of how someon uses a walmart 120V fridge with an inverter, and a whole lot of posts about autromotive engines, alternators, starters, carburators, etc in a boat. Things which are marine usually are deemed so because of salt or humid air, accelerating corrosion rsistant, spark protected per CG rules, designed specifically for an application. Usually, the cost saving move winds up biting you in the a$$.

                              If your boat came with a norcold fridge, get it repaired. They are very repairable, and not THAT expensive to fix.

                              My boat came with one of those amonia P.O.S. fridge. It lasted 5 years and the control board burned up. Dometic wanted $425 for the board, and $25 shipping. For a bit over $500 I bought a norcold.

                              Differences: Amonia: average current was about 6 amps. A 24 hour anchorout: 146 AH. COnsidering this, I went from 12V, 110 AH Delco voyagers @40# to a pair of gold cart batteries @ 70# each.

                              The interior of the fridge, only would go up to 50*. The freezer inside was a pacebo. The thing heated up the cabin to the point where you could actually feel the heat coming from that compartments vent.

                              The norcold: uses a compressor. Current when compressor running, as above, 2.5 amps. Figuring a 30% duty cycle, about .8 amps. Make that about 19 AH BIG difference.

                              The 2.7 Cu ft interior (bigger than the other one) will actually freeze something in th freezer, even in 95* Florida heat. Very little heat put into the cabin.

                              So, read the above, then go get the bargain amonia fridge and save money...........
                              Captharv 2001 2452
                              "When the draft of your boat exceeds the depth of water, you are aground"

                              Comment

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