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Old Jan 14, 2013, 03:58 PM
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Novice wiring questions

I'm just curious how many people are using a standalone BEC for their flight controller and receivers rather than a BEC from one of the ESCs. I would assume a dedicated BEC would be ideal.

Also, does the flight controller supply power to the receiver or does that need to be wired directly to the BEC as well?

If i have it all wrong here, please let me know. I've looked at some of the wiring diagrams and while they make sense for the most part, photos usually work better than diagrams for me.
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Old Jan 14, 2013, 04:06 PM
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I installed a standalone BEC. The BEC in my ESCs were only 2 amps and I thought that was kind of low.

The flight controller receives its power from whichever BEC you are using.
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Old Jan 14, 2013, 04:12 PM
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Originally Posted by jlouden View Post
I installed a standalone BEC. The BEC in my ESCs were only 2 amps and I thought that was kind of low.

The flight controller receives its power from whichever BEC you are using.
What about the radio RX? Is that also powered by the BEC or does it get power from the flight controller connections?
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Old Jan 14, 2013, 04:14 PM
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I'm confused why anyone would want to use the BEC of an ESC? I've read they are less efficient than stand alone BEC's so why not always have a seperate BEC and use becless or OPTO ESC's?

Is it just to save a little weight?
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Old Jan 14, 2013, 04:18 PM
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Originally Posted by Pelagic View Post
I'm confused why anyone would want to use the BEC of an ESC? I've read they are less efficient than stand alone BEC's so why not always have a seperate BEC and use becless or OPTO ESC's?

Is it just to save a little weight?
Usually because it is simple/easy and most ESCs begin used have it already and unless you are driving servos for a gimbal the power draw of the flight controller and Rx are pretty low.
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Old Jan 14, 2013, 04:19 PM
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Originally Posted by brock.travis View Post
What about the radio RX? Is that also powered by the BEC or does it get power from the flight controller connections?
Maybe this helps: http://www.rcplanes4beginners.co.uk/...ng-diagram.php

Looks like it's getting it's power from the controller.
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Old Jan 14, 2013, 04:20 PM
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Originally Posted by brock.travis View Post
What about the radio RX? Is that also powered by the BEC or does it get power from the flight controller connections?
Most Rx get the power via the servo leads that connect it to the flight controller.
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Old Jan 14, 2013, 04:22 PM
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Usually because it is simple/easy and most ESCs begin used have it already and unless you are driving servos for a gimbal the power draw of the flight controller and Rx are pretty low.
Ok that makes sense. So as long as I use a seperate BEC there is no reason I couldn't use OPTO's for any copter?
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Old Jan 14, 2013, 04:26 PM
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Thanks and Thanks.
Pelagic, that image helped my understanding a bit more.
You would just connect the BEC to the battery the same way you connect the ESCs right?
And the only output from the BEC would be to the flight controller?

flitelab, thats what I assumed, but I wasn't sure. Would all leads need power or just one of them (throttle) while the rest were signal only?
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Old Jan 14, 2013, 04:35 PM
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Originally Posted by brock.travis View Post
Thanks and Thanks.
Pelagic, that image helped my understanding a bit more.
You would just connect the BEC to the battery the same way you connect the ESCs right?
And the only output from the BEC would be to the flight controller?

flitelab, thats what I assumed, but I wasn't sure. Would all leads need power or just one of them (throttle) while the rest were signal only?
Just one of them really needs power from the ESC to the flight controller. Some flight controllers are picky about having more than one ESC connected so you may need to pull the Red lead on the others. Other boards don;t care as much and some only take power from one ESC (KK2.0)

From the Rx to Flight controller just one needed as well, but I typically run all between Rx and flight controller but you could just run the signal from the others as long as one has a full connection for the power.
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Old Jan 14, 2013, 04:36 PM
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Originally Posted by Pelagic View Post
Ok that makes sense. So as long as I use a seperate BEC there is no reason I couldn't use OPTO's for any copter?
That is correct, no harm in using Optos. The DJI kits all have Opto ESCs for example, as they use a separate BEC/VU unit for power.
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Old Jan 14, 2013, 05:21 PM
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Any quality BEC recommendations?
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Old Jan 14, 2013, 05:25 PM
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I've been using the Hobbywing ones when required:
http://www.hobbywing.com/product_show.asp?id=209
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