motor question.....

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  • saleens7
    Fast Electric Addict!
    • Apr 2007
    • 1108

    #1

    motor question.....

    on my BBY build, i was planning to use this little inrunner from hobbyking ( http://www.hobbycity.com/hobbycity/s...r_(WaterCooled) )...but i feel that it just wont be powerful enough to push around that 21" hull....i saw a 380 size BL motor my friend had and i seemed somewhat....small....

    so i was wondering if maybe upgrading to either a 540 10s or 8s would be more reasonable....the 10s would pull around 25,000 rpms and the 8s 35,000 (too bad theres no 9s on this site, that would have pulled 30,000....just where i was trying to aim towards)......

    if its a bit overkill, i dont mind having a little extra power to spare...not to mention i wouldnt have to worry much about overheating lol....

    one more question...how many amps would a 540 10 or 8S generally pull?

    also...around what size prop should i run?

    the motor would be pushing a BBY OM 21" mono hull, on 6 nimh cells (and lipos eventually, but that will be later) and a SuperSimple 60A esc.....if that has any effect on prop choice....
    saleens7, the wookie of rc boating
  • Boatman
    Senior Member
    • Jan 2008
    • 796

    #2
    go with the 8S. I would start with (around) 435 prop and run the prop shallow and adjust from there. I dont know about he amps it will pull but after each run make sure to write down how many mah you are putting back in your packs and if temps are good you can speed it up and keep track of the difference.

    Comment

    • Diegoboy
      Administrator
      • Mar 2007
      • 7244

      #3
      Consider this option too. 36mm dia, 540 sized
      "A quick temper will make a fool of you soon enough."
      . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Bruce Lee. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

      Comment

      • Simon.O.
        Fast Electric Addict!
        • Oct 2007
        • 1521

        #4
        I run a 8S in a few smaller 20¨-24¨hulls and can tell you that the 8S loves 31-32mm props. They really unload and scream.
        My 2S rigger runs the 632 and runs 40ish by eye.
        Amps.
        FE calc says between 50-75 in this setup.
        I used to run a 60A chinese speedy happily until it got wet for the 5th or 6th time.
        I am now about to feed the 8S motors I have with a Mystery 100A. That should do it.
        The turnigy motor shown above has some good feedback from people i have written to.
        If you don't shell out for the Feigao 8S then at least get the 50mm long version of the turnigy.
        I also have a 12S run on 3S lipo that performs about the same as the 8S.

        I am no genius or even a racer but I do have a bit of experience with smaller boats and motors and a lot of data that I read.
        If I can help give me a yell.
        See it....find the photos.....sketch it it....build it........with wood

        Comment

        • saleens7
          Fast Electric Addict!
          • Apr 2007
          • 1108

          #5
          Originally posted by Boatman
          go with the 8S. I would start with (around) 435 prop and run the prop shallow and adjust from there. I dont know about he amps it will pull but after each run make sure to write down how many mah you are putting back in your packs and if temps are good you can speed it up and keep track of the difference.
          sounds good....except...the charger im going to be using (old prophet sport), wont tell me any information about the packs.....all it does is beeps when its done and goes into trickle charge ......im going to save up and get a decent triton charger eventually though....

          Diego, thanks for the link, i found this motor to be more in my KV range ( http://www.hobbycity.com/hobbycity/s...000kv_Inrunner )....and i think this cooling jacket is just small enough to work with it.... http://www.offshoreelectrics.com/pro...?prod=gnd-4197 ....but if i remember right i think some of them were prone to leaking....oh well, nothing some silicon wont solve....

          and simon, thanks for the info as well.....guess ill stick with the same esc since you had luck with it...and their cheap to replace in case the amps are a bit oo high....and it seems that the motor choice will be either the one diego showed me or the 8s.....and im kinda leaning toward the feigao.....

          also, this FRED guy pm'd me again reguarding the motor (and rest of my setup) and said that the 2848 is the way to go.........he seems to know what he's talking about...but....i still think that little motor wont be enough so im either going turnigy or feigao....
          saleens7, the wookie of rc boating

          Comment

          • Simon.O.
            Fast Electric Addict!
            • Oct 2007
            • 1521

            #6
            Alex, when I first joined OSE I was in awe of all the BL and lipo setups and felt down there as all I ran was brushed and Ni cells. I now run that gear for two reasons.
            It is cheaper in the long run.
            The power is amazing.

            Back to your needs.
            The 380XL and the 540S have roughly the same rpm and amp figures for a given prop. The 540S will spin a bigger prop at the end of the day. It has more torque and will deliver the wattage (power) better.
            For me the 380 is for smaller, sub 22'' hulls, and where a 540 (36mm dia) can will not fit.
            Lean towards the Feigao as much as you can. It is a solid motor. I know as I am very good at killing this kind of gear. I hate doing so as it costs but I learn from it.

            I would suggest the Feigao 8S on 2S lipo with a 100A capable esc
            http://www.offshoreelectrics.com/pro...?prod=fei-540S

            To go a similar physical size in the Turnigy range it would be better to go with a slightly lower Kv and then step up to 3S lipo.

            Your boat and your call.
            See it....find the photos.....sketch it it....build it........with wood

            Comment

            • saleens7
              Fast Electric Addict!
              • Apr 2007
              • 1108

              #7
              the extra cost will be worth it....and im also givin a little more leniancy for my motor and esc choice since i no longer need to worry about the radio system, flex shaft, and trim tabs (thanks again diego and scotsman)

              i would want to run lipo, but for now i can only afford nimh (not because of the cost of the cells, but the cost of a decent charger).....

              and im know the 540 should fit, i ran the old bby with a 500 brushed, which is roughly the same size, and i was able to fit everything in quite well (except the battery....but that was because the stick pack was too big to really move around....ill run saddle packs for now)...

              i checked out the supersimple 100a esc as well...its not much more $ so i think ill go with it....it can handle way more than ill be throwing at it now so i can probably tranfew it around to future setups

              the only thing is they have no BEC, and the extra weight of a batt pack isnt going to help much....good thing im going for the 540 motor

              and i also just found an affordable charger as well ( http://www.hobbycity.com/hobbycity/s...cer/discharger )....the reviews seem positive...although i still might have to wait a little longer to buy this, it should make running lipos on this setup a closer goal than before
              saleens7, the wookie of rc boating

              Comment

              • Flying Scotsman
                Fast Electric Adict!
                • Jun 2007
                • 5190

                #8
                Saleens, you will need a good charger for the SRX radio and other components. That one Is OK and as in my instructions do not use the Hitec charger as you will be waiting until next month for a charge

                Douggie

                Comment

                • saleens7
                  Fast Electric Addict!
                  • Apr 2007
                  • 1108

                  #9
                  ok FS...i know the charger isnt the best out there, but with the constrained budget i have, its the best i can manage for now......
                  saleens7, the wookie of rc boating

                  Comment

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