Discussions

3DR Power Module

Posted by DG on October 19, 2014 at 7:03pm

I'm building a Sky Hero Spy 750 using Pixhawk and 3DR GPS/telemetry etc.

Is there an alternative to using the 3DR Power Module to power the Pixhawk? I'm questioning the 14 AGW wires being able to handle the current draw from the motors (KDE 2814XF-515). I do wish to monitor the current and voltage in MP.

I'm using a Hobby Wing BEC as backup power for Pixhawk, but am concerned about the power module, especially considering the battery is using 10 AGW wire. I suppose heavier wire could be soldered in place of the OEM wire on the 3DR PM, but I worry about damaging the components on it.

Thanks.

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Replies

  • Peter Everett March 10, 2015 at 6:22am

    Hi,

    Sorry just seen this thread so I'm sure that you've resolved this but this may be of interest to you: http://ardupilot.com/forum/viewtopic.php?f=80&t=9153&hilit=...

    I'm running Y6 with T Motor MT2814 motors that can potentially draw 20A each so I installed an Attopilot 180A and changed the power leads 10awg silicone wire. I have seen 110A max since installing this so worth the trouble imo. In hover, she draws around 30A.

    https://vimeo.com/115958353

    http://www.thebeachresidences.co.uk/stunning-shot-worthing-coastline/

    :o)

  • iskess October 20, 2014 at 9:51am
    I think it will be fine as is. How many Amps will you be drawing in cruise? Max?
    If you want, you can wire in an Attopilot current sensor and a UBEC to replace the PM. I have done this on two planes and it works great.
    • DG > iskess October 20, 2014 at 10:37am

      Thanks. Max current draw is estimated at 60-70, but that would be a rare event. I'm thinking hover will be 20 or below. Cruise I don't know. 

      I should have mentioned the area is cramped as I designed my own PDB and it leaves the rear area smaller. No pics at the moment, will post tonight.

      I like to have redundant backup power for the Pixhawk.

      Once you see the picture it will make things clearer.

      • iskess > DG October 20, 2014 at 11:01am
        No problem with 14g wire for up to 40-50 amps. Occasional bursts to 60-70 will be fine since your lengths are so short.
        Feel your wires after a hard run and see how hot they are. If they are more than warm, you might consider a mod.
        • DG > iskess October 20, 2014 at 7:03pm

          FCjNbfN.jpgI tend to go over on wiring size, and try to use copper whenever possible. In the back left the 3DR PM can be seen. It is a tight fight but I think it will be ok after shortening up the wire, or I'll mod the 3d printed PDB (prototype at this point) to scoot it forward a bit. Inside the green PDB is .035" copper plate with 4mm bullet connectors soldered to it leaving 5 female connectors. 3 + and 3 - for the motors, 1 for the battery/PM and 1 for peripherals (vx tx, BEC etc.)  

          Not much is secured at this point, but hopefully the maiden flight will be by the end of the week. Wish me luck :)

          The ESC's are Maytech 40A slim tube. They seem to be quite responsive with the KDE motors, but only a real flight will tell the truth. I'll be starting with a 8A 45c battery, but also have a Turnigy 10A 10c battery (weighs less than the 8A) to experiment with.

  • DG October 19, 2014 at 7:10pm

    Error in OP: the battery uses 12A AGW. 

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