If you use an RX pack then whats the purpose of the BEC?

 

The using RX battery with BEC had me stumped as well.

From what I have read, the RX battery is meant to be used as a buffer pack or backup. I suspect this is incase if there is some type of calamity with the ESC , the RX battery will give you servo control to auto rotate land your helicopter.

However, in practice, I was flying a logo upside down when the ESC decided to go pffffft. I had a separate RX / voltage regulator for the servos.

But, once I flipped it up right, it was over bushland at that stage, so I couldn't see it when it got behind some bushes, so I did damage it.

In this case the separate RX battery and voltage receiver did kind off help.

I suspect, regardless, of separate RX pack or not, if its going in, its going in.

 

If you use a BEC I would always use some form of backup to make sure in the event of a esc/bec failure. I generally run a Backup Guard. The buffer pack can be used the same way, but it will also charge off the main flight pack... as well as being a buffer in the event of a huge current draw from the servo's.

but except for my 450, if it runs a bec, it has some form of backup.