Originally Posted by 70sflyer
Building Cessna 421 Twin,will be using 2 hacker 40-10,2 castle 75 ESC, 2, 3300 mah battery one for each motor.Question is I want to us Fife 2100mah battery for the receiver.it is 6.6v,will that be to much or do I need a BEC to bring the voltage down.Also i have a 7 ch receiver,do i plug it into ch 7.the rest are full.Thanks

Question, are you using the CC ICE series with the switching power type of BEC?
If so, I've used those with complete success. With a bit of wiring, you can connect both BEC's of the two ESC's to the receiver. But, they have to be separated with a pair of diodes. The diodes called for are special low voltage drop Shottky types, with a current rating on the order of 9 amperes each. Shottky diodes are used all over the place in power supplies and similar items.
WWW.digikey.com sells them for about $2.00 each or so. Digikey sells to anyone with a credit card.
The two attached photos shows how it is done.
Let me know if you've got questions.