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resistor for sabertooth 2x32 - psu 24v 1000w - motor 24v 350W

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by gigi, Mar 28, 2019.

  1. gigi

    gigi Active Member

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    Hallo,
    I have this configuration
    sabertooth 2x32 for n.2 motors 24v 350w 20,5Ah each . the PSU is 24v 1000W like meanwell.
    Can you please suggest a correct resistor to avoid that regenerative current bourn my psu?
    I asked to dimension enginering and they suggest at least resistor 200w 3 ohm
    In the sabertooth box ther are only 2 small resistor 10W and a resistor 200w 3 ohm is very expensive.
    Any suggestion?
    thanks for support
  2. Milani Fabio

    Milani Fabio Active Member

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    Hi Gigi, this is the link of the same subject discussion.
    https://www.xsimulator.net/community/threads/sabertooth-2x32-uno-rev3.12391/
    Same your problem, n. 3 engines and n. 2 power supplies with the same features for DOF 3.
    I purchased n. 6 metytere resistors in pairs in parallel of 6.8 ohms 100w.
    https://www.cariatielettronica.eu/1...100-watt-corpo-in-alluminio-100w-100watt.html
    Hello
    Fabio
  3. gigi

    gigi Active Member

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  4. Milani Fabio

    Milani Fabio Active Member

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    The 6 ohm resistense are hard to find, I don't know why.
    I'm not an electronics expert.
    The value that is closest is 6.8 ohms, I asked a store in my city and he told me that it's fine.
    Hello
  5. bixler13

    bixler13 Member

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    Check car turn signal resistors as well. Here you can get a 2 pack of 50W 6 ohm resistors for $5 USD. Use standard series and parallel connections as required to get the correct resistance and power requirements.
  6. gigi

    gigi Active Member

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    Hi bixler13, thanks for your post.
    I bought these:
    https://www.cariatielettronica.eu/1...100-watt-corpo-in-alluminio-100w-100watt.html.
    N°2 resistor 100w 6,8ohm each in parallel for each motor mean that total resistence is 200w 3,4 ohm. I also asked to dimenson enginering and they answered me that my choice is ok. For 4 motors I bought 8 resistors
  7. Mister_Ray

    Mister_Ray New Member Gold Contributor

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    Hello,
    I'm new here in the forum and would like to build a DOF as an experimental setup. I have 2 24 V motors with 440 W each and a Sabertooth 2x32. Now I'm looking for the right resistances. I calculated the resistor values on the website.
    If I understand correctly, I need 1.3 ohms per 440W motor. Then I have to, for example. 5 x 6.8 Ohm 100 W parallel to B + and P1 and 5 x 6.8 Ohm 100 W parallel to B + and P2
    connect.
    I've often read something as low as 8 amps, but 440W / 24V = 18.33A?
  8. Mister_Ray

    Mister_Ray New Member Gold Contributor

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    I have now reread the instructions for the 2x32 again.
    If I understood correctly P1 and P2 power outputs which can each be loaded with 8A.
    But if I connect only 1.3 ohms at 24V between B + and P1, more than 8A would flow there.
    That would mean with 24V and 8A a 3Ohm 192W resistor would have to be installed?
    Then the resistance would be independent of the engine power, right?
  9. Milani Fabio

    Milani Fabio Active Member

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    Regardless of the power of the motors, Sabertooth can discharge a maximum of 8A.
    I mounted 2 Sabertooth 2x32A with 4 350w 24v motors.
    I put these resistors and everything works fine.
    20190329_103202.jpg Schema 4DOF Milani new 1_7.jpg
  10. Mister_Ray

    Mister_Ray New Member Gold Contributor

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    Thank you,
    for the quick reply. Since I stumbled across the 8A myself. I also considered the same structure with 2 6.8 Ohm 100W. The resistors are not that expensive in this size. Thank you for the picture with the structure makes it a little easier
  11. _cOdaC_

    _cOdaC_ New Member

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    I really like your design which fits my project quite well.
    Can you tell me something about the Wire Gauges?
    Which Gauge did you use for the following connections?
    - Motor to Sabertooth
    - Cables between the resistors
    - Cables to Power Supply
    - Cables to potentiometers
  12. gigi

    gigi Active Member

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    Please excuse me if I am late in replying to your message. I abandoned that project a long time ago to move on to actuators. The thickness of the cables is very important only for connecting the motors to the Sabertoth boards. I don't remember the exact diameter, but I remember using the cables and connectors that are normally used to connect solar panels. Another important thing in my project was to place a heat sink on the boards and also a PC fan to cool them. In this way, even with intensive use, the cards remained at a temperature never higher than 40°. As regards the cables between the potentiometer and the board and between the resistor and the board, very thick cables are not necessary
    • Informative Informative x 1