Hi! Here is a bit of context for the project I’m working on. I am trying to reiterate on a 6-Legged Walking Robot project that I finished a v1 of. The plan is to use 18 MG996R Servo’s, a 2S LiPo battery or 2 Lithium Ion Batteries (Lithium Ion’s were used in V1), 2 chained PCA9685 Servo Drivers, and a UBEC to convert the 7.4 volts into 5v for both an esp32 c3, a fs2a rc receiver, and an ultrasonic distance sensor. The main issue with my first version is that it had enough torque to hold itself up, but barely enough to move forward. I think it is partly due to the weight of the walker as well as the current draw going into the motors.
For V2 I am planning on designing and ordering a custom PCB to manage wiring. I made a first version that I want to iterate on and feel like there isn’t enough current draw that goes into the PCA drivers to sustain the full torque capabilities of 18 servos, so I am wondering if it would be a good or bad idea to have a section of the pcb dedicated to directly powering the 18 servo ports rather than go from battery → ubec step-down to 5v 3a → Servo Driver 1 → Servo Driver 2. For context, I also used a separate ubec dedicated to the servo drivers. I’d love to hear ideas as this would be a pretty big design change in the pcb design
I am also open to running 2 separate becs for each servo driver
You will need at least a 30 Ampere power supply for 18 MG996R and a very heavy duty power distribution PCB, or better, soldered wire connections to each servo.
The servos each briefly draw 2.5A every time they start moving, and for each servo that is continuously active to support the weight of the robot on the legs, plan on continuous draw of 1.5 to 2 A.
Gotcha, that would make sense. Another thought I had would be to run some 6v UBEC’s that have higher amperage to them and dedicate one of two LiPo’s to that connection specifically, connecting the power pins to each servo separately from the PCA9685’s
I’ve read various posts on powering multiple high torque motors that utilize the PCA9685. The discussion of what posts I read in this forum is a very unproductive way of talking about the issue.
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Did you read that when replying to this thread? Because that felt snarky and unproductive to the discussion at hand, and I did not appreciate the delivery of what you were trying to communicate in this help forum
To add some context, in my circuit for v1 I stepped down power from the 2S using the UBEC to power the servos via the PCA9685 V+ and GND Pins. This is separate from a second UBEC that stepped down voltage for the other components. The UBEC dedicated for Servo power connected to the first PCA9685 and I chained the V+ pin similar to how you would chain the SCL and SDA Pins
If You would read the advising topics and provide the requested information replies would be a lot different. Don’t throw a trash bin on us and expect us to dig down and work for You.