Originally Posted by AdamChicago

BEC Question for the Experts: I have read several posts and other links about BECs but still am not knowledgable enough about RC electronics to feel comfortable with an immediate decision.

The question is, do I need a BEC and why?

Planned flying...longer duration, long range FPV:

Current Setup: (Skywalker FPV)
Servos:
- 3 Hitec HS81 servos (flaps and camera pan)
- 3 Hitec HB65 servos (ailerons, elevator, rudder)
- 1 Hitec HB55 servo (rudder)
- (1) possibly an additional servo for camera tilt in future
Batteries:
- Turnigy 4S 4500 (power system, servos, rx)
- Turnigy 3S 2100 (FPV OSD, Camera, tx)
Power System:
- Brushless Motor AX-2814C 1310-980KV
- ESC 45A

What do you think?

Why do you have TWO rudder servos?

It's one giant rudder!! ...just kidding, that was a typo It should read 3 HB65's for ailerons and elevator and 1 HB55 for the rudder.

How do you install the BEC? The install instructions I've found online have both the BEC and ESC plugging into the rx, but how can they both plug into the rx? ...there's only one throttle input? ...where does the other one plug into???

Thanks

Some BECs have a connector that you can plug the ESC lead into and then it passes the signal forward with the power feeds from itself to the receiver (Dimension Engineering). If not just undo the red wire coming from the ESC and heatshrink it. Then use the signal wire, tie the grounds together, and the red wire from the BEC to the receiver.

I really need some advice here guys. I have my kit on its way and need a motor for it. I have looked at all the options in the thread and still can't decide. I think I want to stay 3S for simplicity of powering my FPV equipment. I have a 3530-1400 motor but not sure if that will be enough. I love Scorpion motors for my helis so that is attractive too. Anyone care to convince me?

Originally Posted by chimaera

I really need some advice here guys. I have my kit on its way and need a motor for it. I have looked at all the options in the thread and still can't decide. I think I want to stay 3S for simplicity of powering my FPV equipment. I have a 3530-1400 motor but not sure if that will be enough. I love Scorpion motors for my helis so that is attractive too. Anyone care to convince me?

Try what you have. It'll most likely work just fine, but if you decide you want more power then buy the 3536-1400 motor (but not the XP) later.

Originally Posted by AdamChicago

How do you install the BEC? The install instructions I've found online have both the BEC and ESC plugging into the rx, but how can they both plug into the rx? ...there's only one throttle input? ...where does the other one plug into???

Just to add to Chimaera's information, which was quite good, the receiver consists of three rows of signals: all the blacks (-) are in a row, all the reds (+, which is the center) are in a row, and all of the signals (white, orange, or other colors) are in a row. One one of the channels (any one), you have to feed some power to the receiver, and that power is then available for all the servos. Usually the throttle is the channel used to feed the power, through the ESC, but it can be any one. Since you don't want to get + power (red) from the ESC, you have to disconnect it and substitute the red wire from the BEC in its place (while still providing a ground (-) path for both the ESC and the BEC).
--Jim

BostonJim, thanks...

Based on your comment...I should cut the middle wire going from the ESC to the RX throttle channel. Then plug the BEC into any unused channel in the RX so that the middle/power wire powers the entire RX...would that work? Or is there a better technique?

Or can I just use a Y servo connector to branch both the BEC and ESC into the throttle channel on the rx but cut the middle/power wire from the ESC?

Dont cut that middle wire, just pull the pin out and tape it back. makes it easier to switch it back if you want.

The easy way to join them is a Y connector. The other way it to plug the power pin in place of the pin from the ESC and solder the two ground wires together..

Thanks Ash...just to confirm. Connect both the ESC and BEC to a Y servo connector that plugs into the one throttle channel (3) and just pull the power wire pin out on the ESC but leave all the other wires the same on both ESC and BEC? ...is that correct?

correct.

Also posted something for you in our little thread..lol

Originally Posted by AdamChicago

Thanks Ash...just to confirm. Connect both the ESC and BEC to a Y servo connector that plugs into the one throttle channel (3) and just pull the power wire pin out on the ESC but leave all the other wires the same on both ESC and BEC? ...is that correct?

That's correct Adam.

Originally Posted by AdamChicago

Just to confirm. Connect both the ESC and BEC to a Y servo connector that plugs into the one throttle channel (3) and just pull the power wire pin out on the ESC but leave all the other wires the same on both ESC and BEC? ...is that correct?

Yes. However, if you have an unused channel, you can plug the BEC into that (insteadf of using a Y-cable). The only wire that has to be connected to its correct channel is the signal wire (if any). To pull the pin on the ESC plug, use an exacto knife and pry up the plastic (etc). pin that holds it in place (may be slightly different on different ESCs).
--Jim

Awesome...thanks!

So what happens if you have moth the bec and esc feeding power in to the reciver . It won't over volt and cook it
Will it give redundancy in the event of a bec failure ???