Battery recommendations for MinnKota?

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  • Thorne
    Like my hat?
    • Aug 2005
    • 16414

    Battery recommendations for MinnKota?

    I'm getting ready to set up some sort of electric propulsion with a 12v Minn Kota 48# thrust motor, and am looking for recommendations for an **inexpensive** battery to start with.

    The motor will not be set up permanently in the boat, nor will the battery. I'd prefer not to slop acid all over the place, but the AGM or Gell batteries are pretty pricey compared to the "maintenance-free" well cell batteries. I know that the regular open-top batteries allow better testing and water-replacement, and I have a plastic battery box, but still wonder about the sealed batteries as a better option.

    My boat is 14', weighs about 400lbs, and will have a fairly long cable run from the bow (where I need the battery weight) to the transom-mounted trolling motor. Weight is also a factor as I'll be hoisting the darn thing in and out of the boat.

    I won't be running the system for hours and hours, and realize that a 'proper' setup would consist of dual 6v golf-cart batteries, chargers / testers /meters / etc.

    But at this stage I'd like to pick up an inexpensive 12v deepcycle battery to test with, and might combine it with another deepcycle later on if the system works and I need the extended range.

    There is a lot of info on the web, mostly from battery manufacturers, but it sure looks like the AGM is replacing the gell battery and has a slightly reduced cost - but still 2-3x the cost of a wet-cell battery.



    Learn how a lead acid battery works, more about battery maintenance and the difference between flooded, AGM and gel batteries. Read the tutorial today.


    Any suggestions?
    Last edited by Thorne; 10-12-2006, 11:18 AM.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.
  • johngsandusky
    Senior Member
    • Dec 2003
    • 5554

    #2
    I used a wet cell deep cycle/starting battery to power my 20' sloop for about a year. I mostly sailed up and down the canal whenever there was a breeze, but the battery seemed fine. The sloop weighed 1 ton, the canal 4/10 of a mile long, it didn't leave me stuck. I don't remember how often I recharged it, but not every trip for sure.

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    • carlg
      Member #2989
      • Mar 2001
      • 547

      #3
      A sealed gel battery will do the trick. No spillage and they are available in deep-cycle versions. An 85 amp-hour battery will weigh about 65 pounds. A little heavy; no matter what battery you use, be sure to secure it well.

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      • paladin
        Senior Senior Member
        • Dec 2000
        • 26476

        #4
        Have a brand new one sitting downstairs......come and get it and it's yours....
        Wakan Tanka Kici Un
        ..a bad day sailing is a heckuva lot better than the best day at work.....
        Fighting Illegal immigration since 1492....
        Live your life so that whenever you lose, you're ahead."
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        • Thorne
          Like my hat?
          • Aug 2005
          • 16414

          #5
          My wife just flew out to NYC this morning, maybe I'll have her take a cab up your way and bring it home on the plane?

          ( NOT )

          ;0 )
          "The enemies of reason have a certain blind look."
          Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

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          • Peter Malcolm Jardine
            Senior Member
            • Aug 2002
            • 18515

            #6
            Just buy a cheap dual purpose battery and put it in a plastic box, and try it out. If you need something bigger, or more high tech, you can always use the battery you bought for the car. My sense is that you don't need something huge and expensive. A regular lead acid should be fine.
            Wooden boats are like shingles, recurring, and often painful.

            Comment

            • Nicholas Carey
              Flâneur • Seattle
              • Feb 2001
              • 20335

              #7
              I'd look at Optima batteries -- their "Blue Top" is what they recommend for marine/deep cycle use.

              I believe you can get them at Sears. They're not too hideously more expensive than a good lead-acid battery (Froogle found them for about $180 online).

              The Optima batteries are actually lead-acid batteries, but the case is completely sealed and the plates are wound in spirals. They can be mounted in almost any position -- supposedly even upside down

              Optima also makes a case ("Troll Fury" ) that lets you bridge 2 of their batteries as one: you can configure it in series (24v, double the voltage) or in parallel (double the amperes).

              Here's how these batteries are put together:

              “The big joke on democracy is that it gives its mortal enemies the tools to its own destruction,” Goebbels said as the Nazis rose to power—one of those quotes that sound apocryphal but are not.​
              — Adam Gopnik

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              • Thorne
                Like my hat?
                • Aug 2005
                • 16414

                #8
                From what I can tell, the Optima batteries are AGM, not old-school wet acid. And AGM looks like a much better option than Gell, which it is replacing rapidly.

                But as I said, the cost per Amp Hour looks double for the AGM compared to wet acid. If I was building a serious electric launch, I'd certainly get the good stuff -- but I'm not, and not sure how much use the trolling motor will get. Hence my request regarding the cheaper wet acid style.



                "The major construction types are flooded (wet), gelled, and AGM (Absorbed Glass Mat). AGM batteries are also sometimes called "starved electrolyte" or "dry", because the fiberglass mat is only 95% saturated with Sulfuric acid and there is no excess liquid."
                "The enemies of reason have a certain blind look."
                Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

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                • kc8pql
                  Senior Member
                  • Sep 2004
                  • 3510

                  #9
                  Also note that AGM's must be charged at a lower voltage than standard wet cells. 13.8 v. rather than 14.2 v. While they are "sealed", they are also vented to relieve pressure if overcharged. The higher voltage will cause them to off gas, shortening their life. Be sure the charger you use has an AGM setting.

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                  • Woxbox
                    Senior Member
                    • Feb 2006
                    • 9923

                    #10
                    My co-owner buddies and I just spent a lot of time researching batteries since the old set of 4 golf-cart 6V batteries died. We concluded the advantages of the sealed gel-cells and other more expensive types aren't worth the extra cost.
                    I think, and my own experience bears it out, that careful maintenance of a basic lead-acid deep-cycle battery will get you years of use. In short, pick one up at K-mart - you may even get a good end-of-the-season price now. The main thing is to recharge it fully right after use, monitor the levels and keep it charged over the winter. Batteries that die young have usually been abused.
                    -Dave

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                    • Thorne
                      Like my hat?
                      • Aug 2005
                      • 16414

                      #11
                      Thanks again, everyone! Battery is on the tricklecharger as we type...

                      I hit Kragen's Auto parts on the way home and picked up an Exide Nautilus Gold marine deep cycle battery for $64. 80 Amp Hrs, 140 reserve minutes. Priced out by Amp Hours, the old wet batteries are still a better deal, even if they aren't the 'real thing' for serious electric motor use.


                      I got the NG24 - http://www.exideworld.com/products/m...old_specs.html
                      "The enemies of reason have a certain blind look."
                      Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

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                      • leaotis
                        JuniorJunior Member
                        • Apr 2004
                        • 666

                        #12
                        Don't go yacht, go commercial. A friend of mine owns a golf course and says the Trojans hold up better than others.
                        =~=~=~=~=~=~=~=~=~

                        When we remember we are all mad, the mysteries disappear and life stands explained.

                        Mark Twain

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                        • RodB
                          Banned
                          • Apr 2003
                          • 7596

                          #13
                          I was going to recommend either a Trojan or Rolls Series 27 for about $95...and you would have very good quality batteries. The Rolls (Surette) is probably better than the Trojan but costs about the same.

                          RB

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                          • epoxyboy
                            Senior Member
                            • Sep 2005
                            • 6215

                            #14
                            Originally posted by Peter Malcolm Jardine
                            Just buy a cheap dual purpose battery and put it in a plastic box, and try it out. If you need something bigger, or more high tech, you can always use the battery you bought for the car. My sense is that you don't need something huge and expensive. A regular lead acid should be fine.
                            Whatever you do for the battery, dont scrimp on the cable. If it is undersize, half the battery power will just be going up in heat in the cable.

                            Pete
                            The Ignore feature, lowering blood pressure since 1862. Ahhhhhhh.

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                            • Dan McCosh
                              Senior Member
                              • Mar 2001
                              • 16375

                              #15
                              AGM batteries supply the equivalent power of wet acid for about the same cost, but half the energy. This means they cost twice as much per hour of running time. Advantages are low self-discharge, no liquid to spill, and high resistance to deterioration due to deep discharge. The latter offsets the basic capacity limitation somewhat.

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