Are there any risks when connecting high power motors and small electronics to a common ground?

Thread Starter

markusp00

Joined Jan 9, 2024
2
Hi, everyone!

I am designing the electronics of a drone I'm going to build. A large battery pack will power 6 ESCs and motors. A smaller battery pack will power all remaining electronics, including the flight controller, sensors, etc.

The motors will draw a maximum combined current of ~250 amps. Are there any potential risks with connecting all components (batteries, ESCs, motors, flight controller, sensors, etc.) to a common ground? I have never read about or experienced any problems with doing this.
 

crutschow

Joined Mar 14, 2008
34,455
The motors will draw a maximum combined current of ~250 amps. Are there any potential risks with connecting all components (batteries, ESCs, motors, flight controller, sensors, etc.) to a common ground?
You should be okay as long the motor connection are with separate large wires from the battery, and the electronics have there own wires (star connection).
You don't want any of the motor current running through the electronics ground.

You will likely also need transient suppression on the electronic to prevent any high voltage spikes from the motor control, zapping the electronics.
 

Thread Starter

markusp00

Joined Jan 9, 2024
2
Not normally, does this mean there is more than one supply?
The common point should be a shared common or Star point.
Yes, you can think of it as two supplies: a large 44V battery pack driving the motors and ESCs and a smaller 12V battery pack driving all the other electronics. In my case this is necessary because the electronics has to remain powered on while "hot swapping" the 44V battery pack.
 

joeyd999

Joined Jun 6, 2011
5,283
Yes, you can think of it as two supplies: a large 44V battery pack driving the motors and ESCs and a smaller 12V battery pack driving all the other electronics. In my case this is necessary because the electronics has to remain powered on while "hot swapping" the 44V battery pack.
Unless you plan on some sort of isolation, connecting the grounds is kinda unavoidable.
 

MisterBill2

Joined Jan 23, 2018
18,538
The commons can certainly be tied, the serious caution is to not have motor current flowing in the controls common side and no controls current flowing thru the motors common. THAT is where problems start.
 

LowQCab

Joined Nov 6, 2012
4,075
Many ESCs will have a "Signal-Ground" as well as a "Heavy-Power-Ground".
Be sure to keep them separate,
and run the ESC "Signal-Ground" directly to the Flight-Controller only.
The Signal-Wires from the ESC to the FC must be twisted for their full-length.

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