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Forward AND Reverse low voltage cut out for Lipo's

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  • #1

    Forward AND Reverse low voltage cut out for Lipo's

    What cut outs do people use on their drive motors. I have a kill switch for my weapon which is mono-directional but I cant find a low voltage cut off which does both directions. What do other people use?

    The electronics in the system is a 4 cell 4Ah Li-po, Electronize ESC's, a IMX-1 invertible mixer and 2 GR01 motors.
    Tags: None
  • #2
    Re: Forward AND Reverse low voltage cut out for Lipo's

    low voltage for both directions?!?!? I don't understand.

    Voltage is merely an electrical potential between two points and your voltage cut off will be sitting monitoring the battery. When the potential drops below a certain value, it cuts out. Direction has nothing to do with it as your machine should be setup for positive and negative to be wired up correctly to the cut off.

    I don't bother with a cut off and instead just over spec the size of the lipo pack. Main bonus doing this is that I get far higher discharge rates (easily up to 150A plus) from a large pack.

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    • #3
      Re: Forward AND Reverse low voltage cut out for Lipo's

      All of the Li-po cut offs have this bit of text at the bottom in some form or another...

      CellShield is intended for aircraft with 0-100% style one direction only throttle. A future product will be aimed at cars. -http://www.technobotsonline.com/cell...r /> <br /> If

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      • #4
        Re: Forward AND Reverse low voltage cut out for Lipo's

        Originally posted by Eventorizon
        All I am worried about not is cell inbalance and under-volting the cells to a dangerous level.
        http://www.giantcod.co.uk/battery-teste ... 06197.html

        There are worse ways to spend £3. It's not a cut-off but will help keep an eye on cell balance and low voltage. Like you said though, shouldn't be much of an issue as your lipo is over-spec'd.

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        • #5
          Re: Forward AND Reverse low voltage cut out for Lipo's

          Interesting. I'll admit i never bothered looking at the details of lipo cut offs. I always just assumed they worked completely on the power side of things and never bothered the radio signal.

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          • #6
            Re: Forward AND Reverse low voltage cut out for Lipo's

            This is the problem for us as well.Lipo cut offs all fit between the reciever and the esc and only on one channel and when the voltage drops a robot would go full speed reverse or left or right depending on which channel you connect it. the way i got round this is to connect it to the flip channel on the speed controller(scorpion xl) so if the robot started to drive backwards then i know to stop. There are other types which sound a buzzer or light up an led but they are not very good in a noisy arena and if you cant see the led. Also most cutoffs auto detect the number of cells when they are turned on so you need to have fully charged lipos for them to work or they will detect less cells and you could then run them flat. The new scorpions and sabertooth controllers have built in lipo cutoffs.

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            • #7
              Re: Forward AND Reverse low voltage cut out for Lipo's

              What a farce!

              I'm all for just overspec your Li-Po.

              The round is only 3 minutes, so just make sure you won't drain it in that time.
              You should be balancing the pack after every round anyway (it's a good idea to check it for damage too).
              And if you've fused appropriately then that should protect you against any excessive discharge, say from a short or burnt out motor.

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              • #8
                Re: Forward AND Reverse low voltage cut out for Lipo's

                Originally posted by PJ-27
                What a farce!

                I'm all for just overspec your Li-Po.

                The round is only 3 minutes, so just make sure you won't drain it in that time.
                You should be balancing the pack after every round anyway (it's a good idea to check it for damage too).
                And if you've fused appropriately then that should protect you against any excessive discharge, say from a short or burnt out motor.
                That's fine except we're assuming that we charge between every fight. A RR or RL events, we know our feathers don't use much juice so they have a biggish lipo in them and will run pretty comfortably for three fights. That way if they all run ok we actually don't need to charge them during the show.

                But yes the fuse does protect it too, nice short in BOOM whilst at Barnsley. Blew the fuse but nowt else.

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