Larger ESC's may either forgo the BEC altogether or only provide an analog BEC... though there are exceptions.

As the battery voltage from the LiPo's INCREASES the number of servos the analog BEC ( Battery Eliminator Circuit ) can handle DECREASES.

Normally by the time you hit 14.8v or so, most on board analog bec's may be effectively useless.

Because of this some vendors don't bother to supply an on board BEC or may instead go for a more costly "switching" ( aka "switch mode" ) BEC.

Switch mode BEC's can handle higher voltage levels.

You may find that you can get relatively inexpensive ESC's with NO BEC installed ( often called "opto" ).

There is nothing wrong with these, but you'll have to wire up a separate BEC.

Stand-alone BEC's like this are relatively in-expensive ( approx 9.00/ea ) and easy to wire in.

Here is a picture of a 6A BEC that I wired up with DEANS connectors so that it can be plugged in between the battery pack and the ESC.

It supplies power to the servos and receiver via the small plug.



I can also easily transfer the BEC to another plane, etc.

Don't be afraid of wiring up your own, if you have soldering experience.

If not you may want to consider an ESC with a switch mode BEC.