Results 1 to 5 of 5

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    RC poster
    Join Date
    Apr 2018
    Posts
    2

    Connecting a 8.4 v battery to a motor...

    Hello everyone,

    I am currently in Science Olympiad which is a cool thing which is lots of fun. One of my events is hovercraft and the basic goal of the event is to make the “thing” hover over the finish line. Whenever I went to my first competition I saw that some people used traxxas motors and batteries so I bought some myself. For the battery bought this one

    https://traxxas.com/products/parts/b...p-SubC-3000mAh

    And for the motors I got 2 of these ones (one lift one push)

    https://traxxas.com/products/parts/motors/stinger


    I am fairly new and have no idea how to connect these things together. I would like to connect them to a switch so that I can turn it on and off using a switch. If anyone could give some tips it would be awesome since my next competition is a week.

    Thank you so much in advance,

    Lee


    P.S. I couldn’t find a better place to post this so I am sorry if this section or forum is the incorrect place to have posted this...

  2. #2
    RC Champion MaXXL's Avatar
    Join Date
    Nov 2015
    Location
    South Florida
    Posts
    1,222
    I would not suggest connecting battery power directly to the motors. It can be done and will work but your batteries and motors will not like it and they will have a severely shortened lifespan. With nothing to govern the power, the motors will draw the maximum power and at first, the batteries will see it as a direct short.

    I highly recommend you install RC electronics to portion the power going to the motors. You just need any brushed esc, a receiver, and a transmitter. Technically, you wouldnt even need the receiver and transmitter if you could figure out how to signal the esc to apply a fixed power to the motors. If the esc needs an analog signal, this would be as simple as applying a voltage (not sure how much voltage) to the esc signal wires. Im not sure however because the esc may need a digital signal and in that case you would need the rx and tx.

    If you choose to go the not-recommended route, you could simply connect a relay with a switched control circuit to drive the motors. The motors should be connected in parallel to each other.
    Last edited by MaXXL; 04-12-2018 at 08:05 AM.
    10 RCs and counting 😅

  3. #3
    RC poster
    Join Date
    Apr 2018
    Posts
    2
    The rules say I am not allowed to use any integrated circuits. I’m not sure if an ESC counts as one. Also, I just need to turn the hovercraft on with a switch before, and it just goes straight after until we turn it off at the end. Here are the rules

    Thanks for the help, my other question is that how would I connect the big port in the battery to the ESC if I can get one?

    Thanks so much, I’ll try your ideas!
    Last edited by Lee; 04-12-2018 at 08:45 AM.

  4. #4
    RC Champion MaXXL's Avatar
    Join Date
    Nov 2015
    Location
    South Florida
    Posts
    1,222
    It says resistors and potentiometers are permitted. That will be your ticket then. Just limit the amp draw to 5 amps or so and you'll be fine. Idk the amp limit of those motors or batteries but just dont draw more amps than they are rated for.

    You can either measure the actual amperage being used with a multimeter or you can use ohms law to figure out the theoretical amp draw of the system. The theoretical amp draw will be different once you add a load such as a propeller onto the battery though so actual, measured current under load should be noted.

    It would probably be best to use an appropriately rated potentiometer and multimeter and use trial and error until you get the amps to a reasonable level.
    Last edited by MaXXL; 04-12-2018 at 02:26 PM.
    10 RCs and counting 😅

  5. #5
    RC Racer
    Join Date
    Feb 2018
    Location
    Maryland
    Posts
    152
    I don’t imagine those little stinger motors are going to damage anything being directly connected to the battery. And since it’s being built for a competition, and has no controls, long term life of the battery and motors is probably something you’re not concerned about.

    A stripped down version of what I would do is this. Get a relay that can be triggered at around 8 volts. Run a thin gauge circuit from the battery to an on/off switch that will trigger your relay. Make sure you figure out what the amp draw of the motors will be with a load and size your relay accordingly. And your motors will be connected to the load side of the relay, and the battery will be connected to the supply of the relay, these two with probably 12 or 10 gauge wire.

    So in short, low current circuit from your battery to an on/off switch, and out of the switch to the “control” of your relay. High current circuit from your battery to the supply of the relay, and then from the load side of the relay to your two motors. Add quick connects wherever you think you would need them.
    Last edited by justin13703; 04-12-2018 at 04:20 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •