Complicated Question about Pixhawk 4, 4 in 1 ESCs and offbrand PDB

Pixhawk
1

Hello, I’m using the Pixhawk 4 on a quadcopter build, however, the power management board (PM07) that comes with it is not rated for the required current draw of the motors I’ll be using. So I found this pdb that is sufficient for my motors (200 A).
https://geprc.com/products/power-distribution/gep-pdb-lcsf/

There’s a wiring diagram in the site above that shows the connection with a normal set of ESCs, however, I’ll be using this 4 in 1 ESC

So my question is, how do I connect the 4in 1 ESCs to the Pixhawk and the power distribution board?

2

You don’t really need a power distribution board unless you actually want to measure voltage and/or current. So for your case you could just use the 4in1 ESC and then connect the BEC 2A/5V from the ESC to power the Pixhawk.

And you would hook up the FMU or IO PWM pins (depending on your configuration) to the 4in1 ESC.

If you want to use a power module for voltage and current feedback, you need to find one that supports more current such as e.g. this one: https://drones.altigator.com/mauch-power-module-for-pixhawk-up-to-14s-200a-p-42372.html

3

I’ll need the power distribution board because I have a gimbal and an on-board computer on the quad that will need to be powered by the battery. Ideally, I would prefer to use the power management board that comes with the pixhawk 4 but it only supports 120 A and my motors will be drawing 32 A each at maximum. So will it be possible to use pixhawk 4’s pdb as long the motors don’t run at max? It’s a photography type drone so there won’t be any acrobatics involved, is it a bad idea? I will power the gimbal and on-board computer with a different pdb in this case.

4

You can bench test it under various conditions and check if it goes up in smoke or not :smiley:.

5

I performed a thrust test using the RC benchmark 1520 thrust test stand and at a pwm value of 1908, I got the thrust required to maintain a thrust to weight ratio of more than 2:1, and the motor was drawing 27 A of current. So I’ll set my pwm_max to 1908 and that should allow me to use the pixhawk 4’s pdb safely I believe. Thanks for the help! I also scrapped the idea of using those 4 in 1 esc’s and got regular ones instead.

1 Like
6

I’d like to revive this question to ask a very similar one. I currently am working on a hexapod AG drone project that exceeds the current ratings of the PM07. My question is it possible to only use the PM07 to power the Pixhawk and use a separate PDB capable of more current to run all the power wires to each ESC. It seems like it’d work, but I’d just lose the functionality to measure the current and voltage of each motor.

7

I’d say that’s possible. As long as the current doesn’t go through the power module that doesn’t support it. So you basically just use the power module as a BEC and voltage sensor.