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Adequacy of factory battery setup

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    Adequacy of factory battery setup

    My 3788 has two 8d batteries, one start and one house. I've been given advice that there should be 4 banks, a dedicated start for each main engine, one for the genset and one for the house. I don't know where I would put all of those batteries. You know how advice goes, many espouse the "right" way with that being in reality the "best" way from the standpoint of quality and reliability. I want to add practical into the qualifications. My cruising is limited to one inland river, the Columbia River. I am never far away from assistance. I wonder what the experience has been with the factory setup? If one start battery is sufficient to start the main engines being augmented either by combining with the house battery if need be or recharging with the genset if need be to cover a majority of problems that may come up then that's what I want to do. Having said all that I was at the Portland Oregon boat show during the long period of time awaiting delivery of the boat from So Cal, came across Interstate batteries rep and got a pretty good deal on replacement batteries. I have 400 lbs worth sitting in the back of my truck, 2 8d start and 1 8d deep cycle. I may return one of the start batteries and make room for a 2nd house to have 500 amp capacity. Has anyone added a second 8D start battery and second 8D house to their 3788? If so how did you place them?
    My goal is to one day install 500+ watts solar and use the propane stove for time on the hook or at powerless docks free from any engine noise and smell.
    Tony Bacon,
    Washougal, WA
    Caspian
    1997 3788 Twin Cummins 250hp

    #2
    I found this online, should answer your question.

    https://www.google.com/url?sa=t&rct=...bbkDYaVxoJndk8
    Pat says: DO-IT-RIGHT THE FIRST TIME!

    Bayliner 3870 "ALASKA33)
    Twin 350 GM power
    Located in Seward, AK
    Retired marine surveyor

    Comment


      #3
      Battery power is like oil preferences or Ford vs Chev vs Mopar. Most of it is personal, and it’s all valid. As an example, I took out a pair of beat up 8Ds and replaced them with a 27 starting battery, the same as factory, then a house bank of four golf carts. I don’t turn on the crossover switch. I have a separate 24 series for the Generator. Beyond that I have 4 golf carts for the inverter system that’s not connected to the 12v system, so I feel like I have plenty of redundancy.
      The 27 spins my Hinos just fine however I’ll probably add a second one eventually. If I were to add batteries in your case, it would be for the house bank. I’d do as you are thinking and double up on the house if you can find a home for a third battery. I’ve seen batteries stacked with an automatic drip type system for keeping the electrolyte up. Your big draw and what’s going to limit your non generating time is the refrigerator. Then, of course, it would be your potable water and holding tank.
      What you really need to calculate is you amp hour draw over a typical long lime without generating power, like at anchor or a dock without power. You may want to pick up Nigel Calders book on electrical and boat maintenance. It a bit old and usually available on Amazon. My copy was ar some point sold for a dollar at a garage sale. I bought it for more like $15. There is an excellent section on installation of solar panels. Powell’s may have a copy. I love that place and then it’s an excuse to get some voodoo donuts.
      P/C Pete
      Edmonds Yacht Club (Commodore 1993)
      1988 3818 "GLAUBEN
      Hino EH700 175 Onan MDKD Genset
      1980 Encounter Sunbridge "Misty Blue" (Sold)
      MMSI 367770440
      1972 Chevrolet Nova Frame off Resto-mod in the garage
      Boating on the Salish Sea since 1948

      Comment


        #4
        Thanks Pcpete. I agree there is a lot of personal preference involved. There also seems to be some "standard or recommended configurations". From what I understand the Hino's are great cold temperature starting engines. The Cummins 6BT have an elaborate intake air heating system that draws 100 amps per engine when intake air is below 95 degrees if I recall correctly. Its primary purpose is to eliminate white smoke when the engines are cold but it also aids in cold starting. In warmer climes the intake heat (problematic) is often eliminated or disabled. The engine documents state CCA requirement of something like 1200 amps and I think that is partly due to the intake air heaters draw coupled with the way the alternator works (or not) below 1000 rpm. A 4D battery is borderline under those circumstances however I have read of others using a group 31 in place of the 8d, perhaps that works well when the intake heat is disabled. I have a copy of Nigel Calder's book which very thoroughly describes how to size the house batteries. I'm more of a trial and error guy. I was going to straight out replace all three batteries before I discovered there are only two which gave rise to my questioning as I decide whether or not to return any of them. I kind of wish I would have purchased the 4 cart batteries that I believe would fit in the space footprint of the current house 4d but give me something like 490 amps consuming additional space only in the vertical dimension. As I write this I think I am convincing myself to add the 2nd start battery, return the 8d house battery and obtain the 4 6v bats.
        Tony Bacon,
        Washougal, WA
        Caspian
        1997 3788 Twin Cummins 250hp

        Comment


          #5
          everyone can do what they want to do to their boat, but for most of our purposes as recreational boats, 2 banks are all that is desired or needed...

          a start battery that is used by the genset and both engines is plenty, because as long as one of those units will start on the battery, you will create the power to start any of the others... there is absolutely no reason to hit the start button on all 3 units simultaneously.... so one battery covers all three.....

          IF the start battery has gone bad due to delayed maintenance, and doesnt have quite enough power to crank ANY of the motors, the system should have a provision to use the house bank to start any one of the engines.....

          if one knows their system and keeps up on even the minimum amount of required maintenance, 2 banks is all that is needed... but when one is sloppy or careless and forgets the maintenance, there WILL come a time when not even 4 banks will be enough...

          its not the number of banks, but the number of batteries per bank can make a difference, as the peukert effect will give you exponentially more amps with more batteries in the same bank.... the peukert effect makes no difference or has any relation to the number of banks one has.

          but even more than the number of batteries in the bank, the wiring of the system has to be adequate to charge and supply the power properly to the components. and a poorly laid out, spider web wiring system with under sized wires is NOT considered adequate... if the amps your bank has stored is not being delivered efficiently thru the wiring, more batteries or more banks can prolong the inevitable, but doesnt fix the problem.


          NU LIBERTE'
          Salem, OR

          1989 Bayliner 2556 Convertible
          5.7 OMC Cobra - 15.5x11 prop
          N2K equipped throughout..
          2014 Ram 3500 crew cab, 6.7 Cummins
          2007 M-3705 SLC weekend warrior, 5th wheel
          '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
          Heavy Equipment Repair and Specialty Welding

          Comment


            #6
            Thanks Centerline2. That is good input. I'm kind of a maintenance nut. Gives me piece of mind. I want to be relaxed when I am cruising not fearing some sort of failure looming. I think what I'll do is replace the existing start battery and let it serve the mains and genset. Then I'll return the other two 8D Batts I have towards 4 6v cart sized batteries. That way I don't need to take up any additional space below or add as much additional weight.
            Tony Bacon,
            Washougal, WA
            Caspian
            1997 3788 Twin Cummins 250hp

            Comment


              #7
              Originally posted by Bacon View Post
              Thanks Centerline2. That is good input. I'm kind of a maintenance nut. Gives me piece of mind. I want to be relaxed when I am cruising not fearing some sort of failure looming. I think what I'll do is replace the existing start battery and let it serve the mains and genset. Then I'll return the other two 8D Batts I have towards 4 6v cart sized batteries. That way I don't need to take up any additional space below or add as much additional weight.
              I just installed 2 of the US185XC batteries in my 5th wheel... which are true 12v deepcycle batteries.... they deliver lots of amps and just a slightly bigger footprint than 6v batts.... I went with these because the battery area I have available only holds 3 batteries, so the 12v deepcycles made more sense...

              if one doesnt have room for a full bank of 4 batteries, they may want to stick with 12v batts, because if one only has 2 6v batts in the bank, and one fails for any reason, the bank becomes worthless... with 2 12v batts, the bad one can be removed from the circuit and you can still carry on with only one 12v battery...


              NU LIBERTE'
              Salem, OR

              1989 Bayliner 2556 Convertible
              5.7 OMC Cobra - 15.5x11 prop
              N2K equipped throughout..
              2014 Ram 3500 crew cab, 6.7 Cummins
              2007 M-3705 SLC weekend warrior, 5th wheel
              '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
              Heavy Equipment Repair and Specialty Welding

              Comment


                #8
                I've been around boats virtually all my life but came to liveaboard boating later in life, after a stint living in a converted bus. You can take that for what its worth - my advice still may be worth exactly what you are paying for it but I have lived relatively independant of the electric grid for extended periods on land and on the water.

                First off the recommendation to install 4 banks is beyond silly so I won't even comment on it. It appears you have a genset so my advice is to have one single large bank for house/main engine start purposes and a separate battery to start the generator. That's outside the norm and I'm sure I'll get jumped on for it but it actually works really well. We had two large independant banks on our bus - 2 x 8D start batteries and 3 x 8D house batteries. That was a lot of weight to carry around and most of the time the 2 x 8D start bank got used for about 30 seconds once a day. When we bought our cruising boat, a 43 Defever, it had a single bank of 8 x T105 Trojans hooked to the engines and house as well as a 4D start battery for the genset. At first I thought I needed to change that but I came to really appreciate how logical it was. On a cruising boat you use the start batteries even less than we did on the bus - you start the engines, they generally run all day, then you shut them down in an anchorage and spend several nights without ever starting the engines. Weight is important on a boat so making full use of your batteries is even more important.

                Put a good monitoring system on the main battery bank and use it. We set up our Trimetric so that 50% discharge on the panel was actually still 60% charged and we religiously never let it get below the 50% mark. In actual fact we started the generator if the battery bank displayed under 60% which probably in reality was 65% or more charge remaining. As long as your generator battery is good you've got redundancy and even a 50% bank if its large enough will start your engines. The Trojans aren't designed as start batteries but with over 1000 AH of batteries the difference between start or deep cycle is moot. The battery SOC monitor is as important as how you configure your bank(s). A simple volt meter won't cut it if you are trying to live on battery power.
                R.J.(Bob) Evans
                Cierra 2755

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