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Batteries, Sealed Lead-Acid

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  • Batteries, Sealed Lead-Acid

    Since the 3.5" Sub-driver was designed to use a SLA battery and I Like them, that's what I'm going to use in the T-class model.
    In most of my surface ships I've used the large 12.volt 7.Ah size, but I was thinking about using a lighter weight battery in this sub. So I am considering using the smaller .8Ah size (see 1st picture).
    Is anyone familiar with this battery and how many *Days* or *Thousands of Miles* it will operate a model sub before needing to be recharged? :D
    Or will the 1/48th hull handle the weight of a 7.Ah size (2nd pic), which I have already?
    I know it will fit but is it too heavy and cause a problem with balance?
    Click Pic:
    Attached Files
    Last edited by toppack; 03-03-2009, 03:46 PM.
    Rick L.
    --------------------------------------------
    * Asking Questions is a 'Good Thing',
    Since Learning is Always a 'Good Thing' *

  • #2
    I found out that the .8 Ah batteries weigh 1 pound,
    The 7.Ah are 6.1 pounds.
    Is 6 pounds too much???
    (It will be mounted a little forward of the Center of Hull, length-wise.)
    Rick L.
    --------------------------------------------
    * Asking Questions is a 'Good Thing',
    Since Learning is Always a 'Good Thing' *

    Comment


    • #3
      It might be a case of suck it and see, but one rule I have learnt the hardway with subs is try and keep the boat light. Mass momentum will keep the sub moving on a straight track and a heavier boat can be harder to turn.

      I have gone the NiMH route since, David et.al prescribes now even for large subs the LiPOs. Both need a dry WT section to be housed in and Mike sells one.

      SLAs work just fine too of course.

      J
      John Slater

      Sydney Australia

      You would not steal a wallet so don't steal people's livelihood.
      Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.



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      • #4
        I'll leave enough room between the SD and WTC for a 7.Ah battery and then experiment with different sizes if it doesn't work. I can always go with a smaller one if needed.
        6 pounds does sound very heavy but it would be great if possible, since they will last for days without discharge worries and I have several good ones already.

        I certainly won't need much lead ballast weight, if any? :)
        Rick L.
        --------------------------------------------
        * Asking Questions is a 'Good Thing',
        Since Learning is Always a 'Good Thing' *

        Comment


        • #5
          Originally posted by toppack View Post
          6 pounds does sound very heavy but it would be great if possible, since they will last for days without discharge worries and I have several good ones already.
          try months without discharge!!!
          One of the benefits of SLAs! Been using these for 15 years in all my targets and still do.

          J
          John Slater

          Sydney Australia

          You would not steal a wallet so don't steal people's livelihood.
          Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.



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          • #6
            I found some of the smaller SLAs on eBay at a low price, so bought a few, just in case I need to 'Slim-down' some. :D
            Connectors and wires are provided with those. :)
            (Hey, every little bit helps!)
            Last edited by toppack; 03-04-2009, 11:40 AM.
            Rick L.
            --------------------------------------------
            * Asking Questions is a 'Good Thing',
            Since Learning is Always a 'Good Thing' *

            Comment


            • #7
              In my S Class, I had a number of problems with batteries and weights.
              My best shot was a 4lb 10oz battery @ 6 volts - 12 AH #PC6120A WWW.POWERCELL.COM

              It needs to be shoved well forward,and laid on it's side. My boat is out of whack because of all the reinforcing and buggering about I had to do on the top half of the model. This was a poorly laid-up job, and the molds are now in the hands of more competent people. The top half is too heavy and I have to still have to remove some material and trim the boat out better.

              I laid the battery in the boat and cut some foam blocks to bond around it to stop it from sliding around.

              I also ran the battery in the wet, but used Plastidip on the connections.
              Stop messing about - just get a Sub-driver!

              Comment


              • #8
                Originally posted by kazzer View Post
                The top half is too heavy and I have to still have to remove some material and trim the boat out better.
                Yes, I noticed that about my T-class also (top much to heavy), but I've not desided how best to lighten it. Trying to thin down the fiberglass is to much work, tho i have done it some with my hand-held belt-sander, so I was thinking about cutting out large sections of the deck and using aluminum screen-mesh to fill them to simulate deck-grating, and backed up with foam for strength? That won't be very easy either but what else can I do?

                Why do you suggest placing the battery forward? It seems it would be better in a Central location?
                Last edited by toppack; 03-04-2009, 12:21 PM.
                Rick L.
                --------------------------------------------
                * Asking Questions is a 'Good Thing',
                Since Learning is Always a 'Good Thing' *

                Comment


                • #9
                  The best position for a battery pack is in the middle of the sub, or spread along the length.

                  If you're using a cylinder, and you're using cylindrical based batteries i.e. Ni-mH then you can fit heatshrink over them, and cap them off with RTV silicone rubber, then sling them underneath the cylinder.

                  This will give you good weight distribution, and lower your metacentric height, which on a boat like the T-class is going to be highly beneficial.
                  DIVE IN! Go on, go on, go on, go on, GO ON! http://www.diveintomodelsubmarines.co.uk

                  Comment


                  • #10
                    Originally posted by toppack View Post
                    Yes, I noticed that about my T-class also (top much to heavy), but I've not desided how best to lighten it. Trying to thin down the fiberglass is to much work, tho i have done it some with my hand-held belt-sander, so I was thinking about cutting out large sections of the deck and using aluminum screen-mesh to fill them to simulate deck-grating, and backed up with foam for strength? That won't be very easy either but what else can I do?

                    Why do you suggest placing the battery forward? It seems it would be better in a Central location?
                    You can leave the top alone. It's fine! A bloody good lay-up job! You don't have 4 ton of filler in it to keep the thing lined up like I did. I had to work for months just to get the top to fit the bottom - a nightmare! It will balance out beautifully once you have some keel weight in it.

                    The battery positioned forward is to put the turn point axis further forward, so it makes it easier to turn.Merriman said so! These boats are big and need a large turning circle, and so anything you can do to reduce that is good! (Sorry Andy!)
                    Last edited by Kazzer; 03-04-2009, 01:46 PM.
                    Stop messing about - just get a Sub-driver!

                    Comment


                    • #11
                      Originally posted by kazzer View Post
                      You can leave the top alone. It's fine! A bloody good lay-up job! You don't have 4 ton of filler in it to keep the thing lined up like I did. I had to work for months just to get the top to fit the bottom - a nightmare! It will balance out beautifully once you have some keel weight in it.

                      The battery positioned forward is to put the turn point axis further forward, so it makes it easier to turn.Merriman said so! These boats are big and need a large turning circle, and so anything you can do to reduce that is good! (Sorry Andy!)
                      Okay, Mike
                      I'm having a little trouble with those answers (to both questions) but if you say so, I'll give the top a try, the way it is. I certainly wasn't liking all that work to be done to it.
                      I keep compairing the weight to the light weight plastic hulls, is the problem.

                      My SLA battery position is fixed tho, with it a little forward of hull center (in front of SD), which is a compromize of forward and center. :D
                      Last edited by toppack; 03-04-2009, 02:34 PM.
                      Rick L.
                      --------------------------------------------
                      * Asking Questions is a 'Good Thing',
                      Since Learning is Always a 'Good Thing' *

                      Comment


                      • #12
                        Here's some pics of my handy-dandy pill-bottle WTC for battery connector.
                        It will be soldered directly to battery after I deside which size battery I'll be using.
                        That's a 7.Ah battery in pic.
                        The short 3.5" WTC in pic, with 4 servos in it, is the one I constructed. I moulded the RTV attached rear end-cap for it, using a similar type resin that David uses. The rear end-cap is sloted to hold the servo tray rigidly in place. Having servo trays attached at only one end is Not good, too much flex.
                        Attached Files
                        Last edited by toppack; 03-05-2009, 11:40 AM.
                        Rick L.
                        --------------------------------------------
                        * Asking Questions is a 'Good Thing',
                        Since Learning is Always a 'Good Thing' *

                        Comment


                        • #13
                          Originally posted by kazzer View Post
                          The battery positioned forward is to put the turn point axis further forward, so it makes it easier to turn.Merriman said so! These boats are big and need a large turning circle, and so anything you can do to reduce that is good! (Sorry Andy!)

                          I spoke to Merriman about this and I only got half the story right. It seems you can put the battery as far forward as you like, but you have to put some compensating weight in the aft section. He went on and onBlahBlah
                          so I asked him to write this up 'so it was all beyond me! :o
                          Stop messing about - just get a Sub-driver!

                          Comment


                          • #14
                            Rick that is a hell of big connection housing.
                            I hope it doesn't leak.

                            BTW - what type of WTC (ballast system) is in the photos.

                            J
                            John Slater

                            Sydney Australia

                            You would not steal a wallet so don't steal people's livelihood.
                            Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.



                            sigpic

                            Comment


                            • #15
                              Originally posted by kazzer View Post
                              I spoke to Merriman about this and I only got half the story right. It seems you can put the battery as far forward as you like, but you have to put some compensating weight in the aft section. He went on and onBlahBlah
                              so I asked him to write this up 'so it was all beyond me! :o
                              Yes being doing this for years.
                              In fact I have never setup a sub with the battery midships at all.

                              J
                              John Slater

                              Sydney Australia

                              You would not steal a wallet so don't steal people's livelihood.
                              Think of that before your buy "cheap" pirated goods or download others work protected by copyright. Theft is theft.



                              sigpic

                              Comment

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