bbellfly

My Feedback: (2)

Hey fellow RCers,

I am building an Extreme Flight 47" Yak 54 electric. Looking at the electronics (motor, ESC, receiver & BEC???) for the plane right now. I am confused about something though. At the vendor who sells the plane, they offer a combo package. The motor is a 2814-820-500 extreme flight, the speed controller is a 45 amp air boss, and the confusing thing is a park BEC. The battery recomended is a 2150mah 4 cell lipo 14.4 volts. Well, I've read the info about the BEC, it reduces the voltage to acceptable 5volt or 6 volt for the receiver, depending on which model you buy.
I have been flying electrics for a while. I have several 3 cell 1800mah lipo's. In the two planes I fly, I have Eflite 450 outrunners, and Eflite ESC's. But have never heard of using a BEC. My understanding is the ESC reduced the voltage before it hits the receiver. If not, I am putting 11.1 (more like 12.4) volts into my receiver. Have never had a problem with that setup.

Does the speed controller reduce the voltage to an acceptable level for the receiver or not?


bbellfly

Fliprob17

Many ESC's, including E-Flite, have a Built-in BEC that regulates the voltage. I honestly have never had to have anything separate like that. I have always used ESC's that have them built-in.

gleebs

The BEC is in the speed control. It reduces voltage from the battery by venting excess voltage as heat. There is a limit to how much heat can be vented so there is a limit to (a) the number of cells in your flight pack (b) how many servo's you are running. Most BEC's can only handle 2 or 3 micro servo's. Last year Castle Creations started putting 3 amp BEC's in their speed controls. This will run 4 or 5 standard servos, but you can only use the BEC with up to 11.1v.

If you are running 4 or more li-po cell you will need either the UBEC from Kool Flight or an additional receiver pack. This UBEC is an external BEC that draws directly from your flight pack and is better than an additional receiver battery because of the weight savings. You just have to disconnect the red wire from the receiver plug on the speed control, and plug the UBEC into the battery port on the receiver.

http://www.koolflightsystems.com/ultimatebec.htm

jzrf6c

Check out the following link for a greta description from Hobby Lobby.

http://www.hobby-lobby.com/ubec.htm