You are correct in your understanding of the function of a BEC. Castle Creations makes a 10 amp BEC, thats very good,runs up to 6 full size servos, and is the one I use.
The BEC gets soldered into the outgoing battery leads and plugs into the battery port on your recever, the ESC goes into the channel three port.Some require you to snip the red wire on the ESC to disable its BEC, dont snip the wire, just depress the pin and pull out the prong and tape it up so you can use it again.
Their are other devices such as a battery share, and a UBEC that I use in my 20-35 volt Jets also.
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