Discussions

I am facing a power supply problem which I hope someone can shed a light on with their experience.

This is my current setup:

- 3S 4000 Lipo flight pack powers my ESC (Castle Creations Thunderbird 54)

- I have an External BEC (6V ParkBEC, 1.25 Amps) connected between the ESC and APM board. This BEC also draws power from the Lipo and supplies 6V to the APM.

- Throttle out of APM board is connected to the External BEC

- APM board powers Rx, servos, Xbee, GPS

Whenever I power on my system, the servos are twitching a lot even when the IMU is calibrating (powering up in hardware Manual mode). Once the IMU is done calibrating, the throttle comes on by itself and goes to full power even without giving any throttle command. At this point, I cannot move any servos with Tx (even though I am in manual mode).

However, when I remove the External BEC and power my system using the ESC, I get a very clean power up -servos don't move, throttle doesn't move - it's perfect. I can move the servos around with no jitter in Manual mode. Stabilize mode works well on the ground.

This leads me to believe my External BEC is somehow not supplying clean power to my system. However, I checked the voltage and the current draw from the External BEC and everything looks normal (6V and about 400 ma current draw).

My questions are:

1. What could be causing the issue that I am seeing? I can post a video of the issue if that is helpful. Is 6V too high a voltage for the APM board? The internal BEC of my ESC supplies about 5V.

2. The main reason I am using an External BEC is that I read somewhere that powering the autopilot + servos in Auto mode using an ESC will tend to heat up the ESC a lot. Is this a valid concern?

Thanks!

Neel