Can I connect ground from Buck Converter+ Arduino/ Battery + High Voltage circ?

Hello all, ???

I am a novice working with an intermediate/advanced circuit. So I need advice making it safe! See the attached picture and my questions below.

**(1) **I am using a buck converter to power two servos, and an Arduino to control them. Can I connect the 3S battery ground to the isolated circuit ground from the converter?
(2) I have the same question for the main power supply. ODrive is powered from the 12S lipo, but controlled from the Arduino. Can I connect all the grounds in a "Star ground"?
(3) My whole robot is metal, so I was advised to connect "Star ground" to the chassis. Is this a good idea?
**(4) **I want a safe way to turn the robot off in a worst case scenario. Currently my plan is to use a relay controlled by the Arduino, powered by the 3S lipo. This relay they controls a normally off contactor solenoid switch. (With an E-stop in series). This way I can shut off the motors wirelessly, and via E-stop. Is this a good method?

(5) Any general tips on being save with 12S lipo power?

Thanks so much in advance :sweat_smile:

Charge them on a metal surface or in an Ammo box. Never leave them unattended while charging.
If you can't watch them, don't charge them. Always
have a .50 Cal ammo box nearby. If a battery starts smoking put it in the anmo box and close the lid. Buy an automotive small fir extinguisher to keep in the charging area.
The robot Estop might be a good application for
a wireless remote. The relay and estop sounds ok.

NechevV16:
I am using a buck converter to power two servos, and an Arduino to control them. Can I connect the 3S battery ground to the isolated circuit ground from the converter?

For a "buck" converter, the negative of the input is the same as the negative of the output. They are not isolated.

NechevV16:
My whole robot is metal, so I was advised to connect "Star ground" to the chassis. Is this a good idea?

Hard to say either way. A car - to some extent at least, less so in modern cars - uses the chassis as an actual ground return, but this is not appropriate for your robot.

NechevV16:
Currently my plan is to use a relay controlled by the Arduino, powered by the 3S lipo. This relay they controls a normally off contactor solenoid switch. (With an E-stop in series). This way I can shut off the motors wirelessly, and via E-stop. Is this a good method?

Sounds complicated, like more things to go wrong. :astonished: How do you turn off the turn-off circuit?

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