Issues with PixHawk, one ESC always hot on Quad

Since I setup my quad with the Pixhawk I've had issues and tried a series of things to rectify it.  I've pulled all red wires and taped them up coming from all 4 ESCs.  At that point the motors won't arm or spin up.  I plugged the Motor 1 red wire back in and all motors arms and spin up as expected.  After only a few seconds the one ESC that has its red wire connected heats up to the point of being extremely hot to the touch after no more than 10 seconds of low throttle.  In the last setup I tried all combinations of ESCs wiring with all having a red wire connected, 3, 2 1, and none.  I'm wondering if I just got a bad Pixhawk as I've tried two different brands of ESCs and getting tired of burning up ESCs and Motors in an effort to get this off the ground.

Any idea what I could be missing?  The first round of ESCs had a 5A BEC in all 4 ESCs.  The latest setup has 0.5A BEC in all 4 ESCs 30 AMP Afro ESCs.  The motors are NTM 28-305 800KV. I know for a fact that the motors have no issues as I've disconnect them and hook them to an ESC/Battery not connected to Pixhawk, the motor runs forever without even getting warm.

Is there some sort of jumper I should be setting up? Is it possible to not run any Positive red wires to the Pixhawk and cut the BEC out complete without running a seperate BEC?   I am not running a GPS/Compass and have disabled all Voltage, Current, Compass, and GPS as a result until I can prove this setup works as is.

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  • T3
    How are you powering the PixHawk? It sounds like the red wiring is powering the PixHawk. I had the similar setup on my APM and 1 ESC got hot. As long as it was flying it was ok. Sitting on the bench it would get really hot.
    • I am powering it through the 3DR Power Module, one side is coming from my PDB and the other the 4s LiPo battery.  I spoke with 3DR and they mentioned there should be no need for ANY red wires coming from any of the ESCs as that is an Output rail on the PixHawk.  As a result I have removed all 4 (I'm flying a quad) of the positive red leads from each of the ESCs and am only powering it through the 3DR Power Module.  The issue I'm having now is that the PixHawk will not light up using this method.  If I connect even one red wire of an ESC, as was done previously, the PixHawk comes to life.  I'm wondering if possibly the Power Module is fried.

      It's interesting that your ESC is fine if flying, I had my quad fall from the sky and a motor start smoking as a result of having the red wire connected to the output rail of the PixHawk.  How need to figure out why the PixHawk is powering on.

      How are you powering your PixHawk?

      •   Hi e-leff ,

        Did you figure out what was wrong with the pixhawk? and can you still pôwer it from an power module ?

        • I need to obtain a new power module as mine is fried, as to why the one ESC was getting hot I moved onto a different project and haven't had a chance to retest with the new power module.

      • T3
        I don't have PixHawk. I do have a PX4, which is an early PixHawk. I power it with 3DR power module.
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