Need advise powering servo rail with Opto ESCs

Hello forum!

While I’m learning how to solder XT60 to 10 AWG wire, let me ask you a question…

RPi3 and Navio2…

I’m using the HK Pilot Power VI Module with Opto ESCs. So I need to power the servo rail…

The PDB above has a BEC with 5V/1A output and I can solder a servo wire to it.

I also have a switching BEC (selectable 5V/6V with max output at 5A) that I can solder to a 12V output on the PDB.

Which way is better? Is 1A enough to power the servo rail? The PDB has a power module built in and I will be connecting that to POWER port on Navio2.

Any port (1-14) on the Navio2 board can be used to power the servo rail?

Please advise.

Thank you,


Hi! I was not able to find information about 5V/1A output on this PDB, only about 2.5A UBEC which probably has output on the power port. Servo rail should definitely be powered from a separate power source. OptoESCs probably won’t consume a lot of power from this side, but it’s better to check the specs anyway.

Thank you. You are right. Where did I come up with 1A?

2.5A should be sufficient to power RPi and Navio2, right? Do you think there are any advantages in using as separate BEC?


Yes, 2.5A should be more than enough for RPi and Navio.
It is okay to power then from the BEC on the PDB, no need for another one.
Servo rail has to be powered from a separate source.

Oh. Sorry for misunderstanding… I meant that for the servo rail.

The PDB has a 6 pin plug to connect to the POWER port on the Navio (highlighted in red).

I can solder the servo rail power wires to the contacts highlighted in orange. Any idea what the I and V contacts are for? My soldering skills are sloppy at best and I’m a little afraid to unsolder the 6 pin connector that is on the other side.

On the other hand I can solder a BEC to 12V contacts highlighted in blue and use that to power the servo rail. The BEC I have is Turnigy 5A (8-40v) SBEC for Lipo and another BEC (Dr. Mad Thrust series 3A BEC with Inbuilt Aux Controlled On/Off Switch for Accessories) is in the mail.

Or even better to solder the BEC to one of the Out+/Out- contacts and keep 5V and 12V outputs for other devices. I’m a beginner and it’s hard for me to plan ahead in this case (like to use 12V output for a camera seems logical).

What do you think?


This is a PDB with integrated power module.
I = current sensing output
V = voltage sensing output
Do not solder anything to the pads. They are just a duplicate to the 6 pin connector on the top.
Connect the 6 pin connector to the Navios power port and it will power the Rpi/navio combo as well as providing voltage and current sensing.
You will need a seperate BEC to power the servorail.

1 Like


That’s what I did. I soldered two BECs that I mentioned above to two pairs of Out+/Out- connectors. One to power the servo rail and another for future use. Seems to be working fine. I connected everything and it booted. Getting 'GPS: No fix". Reading threads on that. Looks like before I can get past that I won’t be able to arm the ESCs and test the motors.


If you are indoors and in a city, you will have a hard time getting a GPS fix. Just connect Missionplanner or whatever GCS you use to APM and search the full parameter list for “arming_check”. Set it to 0 (and click write) while you are testing and do not forget to reenable it before you go out to fly!

Thanks again!

I got the GPS fix even tho I am indoors. But it’s “drifting” in MissionPlanner. Compass calibration?

Also got all the motors spinning!

Now tuning and whatnot… before I will take it outside.


It will always drift when indoors. It has nothing to do with compass calibration as long as it does not rotate.

Heh… You just saved me a lot of time right there. :slight_smile: Was going to read up on that.

I will check outside later on then. Trying to level the motors and calibrate the ESCs. At constant throttle after some time one of the motors stalls.


As soon as you raise the throttle all the stabilization calculations start. It is not advisable to let the copter sit with throttle raised and not taking off. Especially the I-Term of the PID algorithm tends to wind up on sensor drift alone. While testing with props off, nothing bad will happen, but if you do this with props, the copter will eventually tipp over as soon as you try to take off. You will never see all motors run at the same speed for a long time, as long as they are controlled by an armed/flight-ready flighcontroller.

Got it about ESCs.

Just showing off… :slight_smile:

It’s not all tied down yet but I’m just testing.


PS. I got a modified vibration dumping mount to fit this frame. Same as the one in the docs but modified lower part. I had to dremel it a bit but the guy who printed it for me promised to adjust the files and I will share when he’s done.


GPS drifted in MissonPlanner even outside. Ground speed always not 0.

What am I missing?


Outside on an ooen field or between buildings?

I’m in the woods really. I’d say… maybe half an acre of a lawn. Car GPS and phone GPS are pretty accurate…

@atpa8a GPS performance will be degraded by the trees around. GPS in the phone works differently, it’s output coordinates are highly smoothed.

Thank you.

That shouldn’t prevent me from flying LOS, correct? I got all hardware in the Initial Setup in the MP calibrated. Still finishing reading on Flight Modes and Failsafe. And the props (APC Slowfly) are still not balanced.

But I want to get this thing into the air… just up and down. To test if it will even fly.Just increase the throttle… Any recommendations/precautions?

Another question. Is it OK to use rubber cement to attach the protection piece for the barometer? Should the black foam from the metal boxes in which the motors (Turnigy Multistar) came do? Or foam pad from an old motherboard packaging?



So I tried to take it in the air yesterday. It was lifting off but it seems like the battery throws the weight off balance. It did rise about an inch but it was sliding backwards and fell on its back side. Damaged the props a little bit. Just chipped it in a couple of spots. Can I fly on slightly damaged propellers while waiting for the new ones?

I double checked the motor order but that seems correct.

I thought the autopilot would compensate for the weight distribution.

Looking for the solution.


The foam has to be an open cell type. It’s hard to say which one comes with the packaging. You should be able to breathe though the open one if it’s not too thick.

It’s not recommended to fly on damaged props. They cause vibrations and may result in damage to the hardware.

Regarding tilting on the take off please read the troubleshooting section in the Ardupilot docs.