Use BEC or no?

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  • Tony
    Senior Member
    • Feb 2008
    • 413

    #1

    Use BEC or no?

    Should i use BEC that comes with ESC, or use a seperate RX pack?
  • AndyKunz
    Fast Electric Addict!
    • Sep 2008
    • 1437

    #2
    Depends on your power system, the ESC, and what type of running you do.

    Andy
    Spektrum Development Team

    Comment

    • Tony
      Senior Member
      • Feb 2008
      • 413

      #3
      Originally posted by AndyKunz
      Depends on your power system, the ESC, and what type of running you do.

      Andy

      9XL Feigao
      ETTI 125 amp ESC +BEC
      2p3s 11.1v 5000mAh series
      x442 or x642 prop

      I'm thinking about using a seperate RX pack, and Lipo Low Voltage Cutoff device.

      Comment

      • Fluid
        Fast and Furious
        • Apr 2007
        • 8012

        #4
        You forgot to tell us the type of running you do.....also knowing the type of radio would be helpful.

        WIthout knowing everything, it is tough to go wrong with a separate receiver pack as long as you keep it charged - get a 1400 mAh 5-cell pack and you will have fewer risks. A LiPo cutoff is a great investment, especially for sport boaters.


        .
        ERROR 403 - This is not the page you are looking for

        Comment

        • Tony
          Senior Member
          • Feb 2008
          • 413

          #5
          Originally posted by Fluid
          You forgot to tell us the type of running you do.....also knowing the type of radio would be helpful.

          WIthout knowing everything, it is tough to go wrong with a separate receiver pack as long as you keep it charged - get a 1400 mAh 5-cell pack and you will have fewer risks. A LiPo cutoff is a great investment, especially for sport boaters.


          .
          Fluid

          It will be sport running. Its a Futaba 2pk am radio that came with the boat. Gonna change to 2.4ghz soon. Whats a good lipo cutoff i should get. How about Lipo Shield Low voltage cutoff?

          Comment

          • Fluid
            Fast and Furious
            • Apr 2007
            • 8012

            #6
            I have used the LipoShield and liked it. With the cheap radio it is even more important to have clean receiver power - go with the Rx pack. The 2.4 radios seem to do better with 6.0 volts, another reason to go with a 5-cell pack. Another option is to use an external opto-BEC, but that's even more cost. Just call me old-skool....


            ./
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            Comment

            • azjc
              Member
              • Sep 2008
              • 57

              #7
              I have always used a BEC with my land vehicles but I make sure it is a quality one though.I use the Western Robotics HV model which I am pleased with...I would stay away from Castle BEC, there have been reports that when they fail they allow the full amount of current to pass through. This will fry either your servos/Rx. I suppose the only safe method is a RX pack

              Comment

              • ApacheDude
                Member
                • Sep 2008
                • 83

                #8
                BEC questions...

                So what are you really improving by use an external RX pac?

                1) Reduced draw on main batteries
                - Is this significant? What about the added weight?
                2) Stable RX voltages. No need to worry about sudden voltage drops during peak power draws?

                3) Other?
                Boats:
                Proboat Apache 24
                Proboat Blackjack 26 Brushless

                Comment

                • Fluid
                  Fast and Furious
                  • Apr 2007
                  • 8012

                  #9
                  The increased draw on the drive packs is meaningless. The real advantage is eliminating potential interference to the receiver through the ESC. This has been a real problem in the past with BECs, but seems less of a problem with modern BECs.

                  The other advantage is the higher voltage with a 5-cell pack. Many BECs only put out 4.8 volts, yet most modern radios and servos work better with 6 volts.



                  .
                  ERROR 403 - This is not the page you are looking for

                  Comment

                  • ApacheDude
                    Member
                    • Sep 2008
                    • 83

                    #10
                    Originally posted by Fluid
                    The increased draw on the drive packs is meaningless. The real advantage is eliminating potential interference to the receiver through the ESC. This has been a real problem in the past with BECs, but seems less of a problem with modern BECs.

                    The other advantage is the higher voltage with a 5-cell pack. Many BECs only put out 4.8 volts, yet most modern radios and servos work better with 6 volts.



                    .
                    This make sense. I never thought about interference.
                    Boats:
                    Proboat Apache 24
                    Proboat Blackjack 26 Brushless

                    Comment

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

                      #11
                      Here is a bit of interesting reading on the subject.

                      http://forums.offshoreelectrics.com/...ead.php?t=5025

                      FWIW I now use a 9V square cell in a couple of hulls and a standard 4 cell nimh in the other 2.
                      If you can take the wieght and room a 5-cell pack like Jay suggests is the go.
                      After all that I am now seriously looking at a UBEC as neither of my BL speedies have bec output and as far as I am concerned nor should they.
                      I have had the world supply of problems before when I ran mostly brushed setups with speedies that had no opto on the signal line and a BEC to boot. RF all over the place and a few very close calls with the pond edge.

                      IMHO opto's in the speedy are a must whether it is BL or Br.
                      I am happy to take the weight of a Rx pack or UBEC if the reliability is the there.

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

                      Comment

                      • 785boats
                        Wet Track Racing
                        • Nov 2008
                        • 3169

                        #12
                        Hi Tony.
                        Just to confuse you a bit more I'll add my experiences on this topic.

                        If the ESC comes with internal BEC, I've always used it. Both brushed & brushless. Never had a problem.

                        If the ESC did not come with an internal BEC, I always use an UBEC. This one.

                        As you can see it has up to 42V input, a 3A output, & can be switched to 6V output.
                        I've never used a seperate battery pack in either my FE or scale boats.

                        If you are using a voltage higher than 12 cells or 4s Lipo, you should use a seperate battery pack or UBEC. This is because at the higher input voltage the BEC circuit has to work harder to drop the voltage to the 4.8V & thus generates more heat & can fail.

                        NOTE If you do run a seperate battery pack or UBEC with an ESC that does have an inbuilt BEC, you should disconnect the red (center) wire from the reciever plug.
                        Otherwise you have two voltages supplying the reciever. This can cause a failure of the reciever as the two different voltages try to balance themselves through the reciever rails. At least that's how it was explained to me.

                        Hope this helps a bit.
                        Paul.
                        See the danger. THEN DO IT ANYWAY!!!
                        http://forums.offshoreelectrics.com/...hp?albumid=319
                        http://forums.offshoreelectrics.com/...hp?albumid=320

                        Comment

                        • Tony
                          Senior Member
                          • Feb 2008
                          • 413

                          #13
                          Originally posted by 785boats
                          Hi Tony.
                          Just to confuse you a bit more I'll add my experiences on this topic.

                          If the ESC comes with internal BEC, I've always used it. Both brushed & brushless. Never had a problem.

                          If the ESC did not come with an internal BEC, I always use an UBEC. This one.

                          As you can see it has up to 42V input, a 3A output, & can be switched to 6V output.
                          I've never used a seperate battery pack in either my FE or scale boats.

                          If you are using a voltage higher than 12 cells or 4s Lipo, you should use a seperate battery pack or UBEC. This is because at the higher input voltage the BEC circuit has to work harder to drop the voltage to the 4.8V & thus generates more heat & can fail.

                          NOTE If you do run a seperate battery pack or UBEC with an ESC that does have an inbuilt BEC, you should disconnect the red (center) wire from the reciever plug.
                          Otherwise you have two voltages supplying the reciever. This can cause a failure of the reciever as the two different voltages try to balance themselves through the reciever rails. At least that's how it was explained to me.

                          Hope this helps a bit.
                          Paul.

                          Paul
                          Thanks for the infos. You've just sumed up why my other esc failed.
                          I am going to use 2p3s 11.1v in series. I bought a LipoShield low voltage cutoff device, and use it instead of the built in BEC. I'll use a seperate 6v 5c pack for the RX as well.

                          Comment

                          • 785boats
                            Wet Track Racing
                            • Nov 2008
                            • 3169

                            #14
                            I am going to use 2p3s 11.1v in series. I bought a LipoShield low voltage cutoff device, and use it instead of the built in BEC. I'll use a seperate 6v 5c pack for the RX as well.
                            Hi Tony.
                            I'd just like to clarify something here. It may just be a typo on your part, but it is the 6V battery pack that replaces the BEC, not the Lipo Shield as stated above.
                            Cheers.
                            Paul.
                            See the danger. THEN DO IT ANYWAY!!!
                            http://forums.offshoreelectrics.com/...hp?albumid=319
                            http://forums.offshoreelectrics.com/...hp?albumid=320

                            Comment

                            • Tony
                              Senior Member
                              • Feb 2008
                              • 413

                              #15
                              Originally posted by 785boats
                              Hi Tony.
                              I'd just like to clarify something here. It may just be a typo on your part, but it is the 6V battery pack that replaces the BEC, not the Lipo Shield as stated above.
                              Cheers.
                              Paul.
                              Paul,
                              It was a typo. The device is for lipo low voltage cutoff. 3v/ cell

                              Comment

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