UBEC or one ESC bec for powering electronics on FT Bronco?

[Black Bart]

I'm building a FT Bronco. This is my first Flite Test plane. I bought the Power Pack Twin B package with the speed-build plane kit, so I have the power Y-harness. This would suggest that I use one bec from one ESC to power the electronics, with the other ESC's bec's power wire disabled. Is that how you guys do it? I've built many twins before, and I have always had a UBEC powering my electronics that was connected to the power Y-harness on the battery side. So this would be the first time that I've used one bec from one ESC to power the electronics instead. Intuitively, it seems asymmetrical to me to use only one bec from one ESC instead of using a UBEC, which is why I'm asking how you guys do it.

 

[SSgt Duramax]

On the only twin I've had I just plugged both BECs into the y harness, then plugged it into the Rx. The voltage should be fine, but in theory amperage would be doubled.

 

[FlamingRCAirplanes]

On the only twin I've had I just plugged both BECs into the y harness, then plugged it into the Rx. The voltage should be fine, but in theory amperage would be doubled.

In practice one bec would blow. Just take the red wire out of one of the ESC’s. Then use the other ones power.

 

[Merv]

....This would suggest that I use one bec from one ESC to power the electronics, with the other ESC's bec's power wire disabled. Is that how you guys do it?....

Yes.
On the Rx, all positive pins are connected and all of the negative pins are connected. If you did not disconnect the positive pins from one of the ESC’s, they could end up fighting each other. One calling for a slightly higher voltage and one a slightly lower voltage.

In quads, they use opto ESC’s, that is ESC’s with out a BEC. Just a signal wire and a ground wire, no positive wire.

 

[Pieliker96]

In practice one bec would blow. Just take the red wire out of one of the ESC’s. Then use the other ones power.

Depends on the type of BEC. Most linear regulators (ex. LM7805) are fine with being put in parallel, whereas switching regulators aren't. In any case using just one BEC is good practice unless you know for certain they're linear regulators.

Another thing I've done with past with twins is to run some of the servos off the second BEC without joining the two circuits. This can be accomplished by removing the power pins from the servo connectors and respective ESC and bridging them together - a spare pin header with the connections commoned at the back will do the trick, as will soldering and crimping (though they aren't reversible).

 

[FlamingRCAirplanes]

Depends on the type of BEC. Most linear regulators (ex. LM7805) are fine with being put in parallel, whereas switching regulators aren't. In any case using just one BEC is good practice unless you know for certain they're linear regulators.

Another thing I've done with past with twins is to run some of the servos off the second BEC without joining the two circuits. This can be accomplished by removing the power pins from the servo connectors and respective ESC and bridging them together - a spare pin header with the connections commoned at the back will do the trick, as will soldering and crimping (though they aren't reversible).

Almost all ESC’s come with switching regulators now. Linear over heats way too easily.

 

[Bricks]

I'm building a FT Bronco. This is my first Flite Test plane. I bought the Power Pack Twin B package with the speed-build plane kit, so I have the power Y-harness. This would suggest that I use one bec from one ESC to power the electronics, with the other ESC's bec's power wire disabled. Is that how you guys do it? I've built many twins before, and I have always had a UBEC powering my electronics that was connected to the power Y-harness on the battery side. So this would be the first time that I've used one bec from one ESC to power the electronics instead. Intuitively, it seems asymmetrical to me to use only one bec from one ESC instead of using a UBEC, which is why I'm asking how you guys do it.

You have it right just do what you said above and your golden. For me the only time I will use a UBEC is when I have an enormous amount of high demand servos.