Powering 10 servos from a single Li-Po

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Yakupsky

Joined Mar 9, 2020
1
I could use some perspective on a circuit I'm planning to build. It's a robot with 6 standard servomechanisms and 4 microservos. I'm set on using a single power source and three step-down converters to feed most of the servos + Arduino Uno + PWM driver with 5V but also supply 6V to two servos to maximize the torque and 7.4V to a higher range (6-8V) servo that has some serious lifting to do.

I suppose the questions that are bugging me are:
  • Is this setup considered common ground since everything comes back to the same accumulator? Some motors are powered through different converters than Arduino that controls them and I'm too new to this electronics business to not be a little worried.
  • Will the battery provide only the current that is required or is it not that simple? If I splice the output of a 5V converter between a high-current servo driver and a low-current Arduino could there be some unsolicited amperes where they're not needed?
  • Would the grounding require a dedicated plane of some kind, as there occasionally might be a serious current draw? Or is not an issue if it all mostly goes through wires (assuming they have proper thickness)?

PDF schematic included.
 

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dl324

Joined Mar 30, 2015
10,467
Just be mindful of any ground wires carrying significant current. I'd use a star arrangement for ground as much as possible..

FWIW, here's your cartoon for the benefit of others; I prefer schematics.
1585584204252.png
 

djsfantasi

Joined Apr 11, 2010
6,334
The other consideration you must account for is the total current requirement of the loads/RC servos connected to the Arduino. Since you are NOT powering the servos with the Arduino, you have some flexibility as the Arduino only powers the control signal. And even though you have external supplies, the total current draw from your battery may drop the voltage and things will stop working.

An Arduino pin can only supply 20mA reasonable, but for a total less than 200mA.

While the battery may supply enough current, it may not last too long.

I haven’t performed a power analysis yet, but you need to do it yourself.

I once ran 11 hobby RC servos snd controlled them with a Mega2560. But they were externally powered by a 5VDC 8A power supply
 

Wolframore

Joined Jan 21, 2019
1,741
Seriously don’t know where to start with this one, did you try the Arduino.cc forum?

there are so many issues you might want to break up your project and get one thing working first.
 
Last edited:

KeithWalker

Joined Jul 10, 2017
794
I have driven multiple servos using an Arduino to control them. For the best, trouble free arrangement, use an extra buck converter to power just the Arduino and wifi interface. Servos can draw a lot of current and cause transients that can reset the Arduino if they are on the same supply. Use a star connection for the grounds as recommended above.
Regards,
Keith
 
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