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  1. #1
    Flight Cadet
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    power the controller from ESC BEC?

    I have a BEC on each of my 4 ESC's and no servos or anything that really needs 5v besides the controller itself.

    Why is it that the controller cant draw its power from the BEC via the esc leads like other controllers do?

    why do we need a separate battery for the arduino?

    and i know the Arduino has a voltage regulator, and you CAN run it directly off your main motor battery... but why do that when you have a plentiful supply of 5v already created and waiting?
    (and i sometimes run higher voltage than those lil regulators might like, so i would rather avoid that.


    I was wondering if there is a reason i couldn't solder a wire between all the red ESC pins and all the black ESC pins on the shield (from below) and feed them into the arduino's power jack?

  2. #2
    Flight Cadet
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    ok, well no one seemed to have an answer... So i got my own answer.

    There is no reason, it actually works AMAZINGLY. i just took one of the long ends i nipped off one of the LED's and soldered it across all the negative pins of the ESC's and did it again with the positive pins... so you get the combined amperage of all the BEC's at 5v. i then soldered some wires from the bottom of the power connector to my newly soldered positive and negative jumpers. now the whole unit comes to life at one time, no counting on the lil arduino regulators, no extra batteries or anything.

    thanks for reading.

  3. #3
    Senior Pilot lokling's Avatar
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    Beware this might not work reliably in the long run - its not powering the arduino from the BEC that is the issue, but having BECs wired in paralell. If you google it you´ll find many discussions about this, ie http://www.rcgroups.com/forums/showt...1126572&page=7 for instance.
    Beware of programmers who carry soldering irons

  4. #4
    Shouldn't one BEC be enough to power the arduino? I don't think connecting all 4 BEC terminals together is a good idea.

    For v2 and later shields, you would lose the battery monitor feature powering from BEC, though you should be able to modify the circuit by connecting the resistor divider to the LiPo instead of Vin.

    The advantage of powering arduino from BEC is less power lost due to linear regulator heat dissipation. Someone in arduino forum ran a heat test and the sweet spot for arduino power input is 6v.

    I thought about using BEC or use a dedicated dc-dc step down circuit (you can get these for like $1 or less) but thought since the flying time of the quad is only a few minutes that the advantage would be minimal compared to the trouble you need to go through.

  5. #5
    Moderator AeroQuad Core Software Developer kha's Avatar
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    Well most ESCs have linear BEC on them only some big ones have switching bec.

    Also the powerloss is negletible compared to what motors use.
    quad(X)1: AQ + mega + v2 shield (with baro) + turnigy plush 30A + Turnigy 2217 + APC 12x3.8 (camera onboard)
    quad(X)2: AQ32 at Baloo / DJI F450 / A2212-12 / 30A ESC:s / 10x4.5 (camera onboard)
    quad(X)3: Naze32 / DJI F330 / RCTimer 2212-9 / Aeolian 20A / 8x4.5
    Generic: Turnigy 9x with telemetry mods with FrSky 2Way, GoPro Hero HD, 1.3 & 5.8 vTx

  6. #6
    Senior Pilot allanGEE's Avatar
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    Thought I read somewhere that if a motor suddenly pulls a lot of power, you risk a brown out on BEC -- so the voltage drops for the arduino. Also the recommended input voltage for the Mega 2560 is 7-12 volts. The input voltage limits are 6-20 volts. So 5 volts during flight is scraping the bottom of the voltage barrel -- and if the potential brown out risk is real...
    One hover and you're hooked!

  7. #7
    Senior Pilot wooden's Avatar
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    First of all, the battery monitor won't work if you power from a BEC as it can't read the raw voltage. Secondly, it's not that you CAN'T power from a BEC, but why would you when you can just plug a 3S or 2S straight into the Arduino? As kha said, the power loss is negligible and you don't risk losing complete control if an ESC suddenly pulls more power to the motors and can't supply the FC properly.
    push the envelope, watch it bend.
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    miniquad w/ AQ32 running aq32Plus


 

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