Is common supply for arduino and brushless ESCs good practice?

Other Hardware General Electronics
1

I've got 3x 10Ah Lipo batteries that sit at ~14V fully charged. They are being used in a DIY RC Powerwheels project to power:

  • Arduino Mega w/Buck Converter to 5V pin
  • 10A Cytron Motor Controller Powering a wiper motor to control steering (PID using a pot)
  • Two chinese ESCs 60A powering two 3660 3800kV brushless motors

My question is should I:

  • Separate 1 battery for arduino power and wiper motor and use the other 2 for powering the ESCs or
  • should I just combine all 3 batteries to a common supply?

I'm worried the noise generated by the ESC in the supply could bring problems to my steering PID controller that uses a 5V potentiometer for the feedback loop. I've currently got the prototype working decently but it would be easier to manage all the batteries on one common supply for charging them. My DIY steering servo seems to get the jitters when my 5V supply gets noisy. When I was using an LDO for 5V and it overheated, the steering would start getting shaky. The arduino is powering 100mA to the radio and I suppose the ~0.150A total of drop from 14V to 5V was too much heat for an LDO (L7805) so now I'm on a buck converter (5V USB car charger stripped down)

2

Clearly linear regulators (LDO) are quite inappropriate for anything requiring any significant amount of power.

A proper switchmode regulator should not pass through any noise. There might be enough ripple on its output to cause trouble in particularly critical audio applications, but as long as it is regulating despite sags in the main supply as the motors operate, there is no reason you should need a separate supply.

What is however important, is that you understand proper practice of common grounding such that your analog grounding for potentiometers and such is separate from the power grounding, coming together only at the analog inputs. It's all a matter of lead routing - and keeping supply, signal and ground always paired, together in bundles from one part to another.

3

Paul thanks for your guidance.

I have re-read the common grounding sticky post. Just to confirm, you're saying for all the pots on my project make sure to run +5V, signal, ground as 3 wires directly back to the arduino and not assume that I can ground the pot elsewhere that leads back to battery ground. Please confirm.

Second, do you have any recommendations for specific buck converters for my <1A application? In the future, I plan to add a good amount of RGB LEDS (5As worth) that operate at 5V. Should I get 1 buck converter for the arduino logic and then another one dedicated to my lighting down the road?

4

Well the LM2596 converters are ten-a-penny, handle an amp or two each.

5

bigbangus:
Just to confirm, you're saying for all the pots on my project make sure to run +5V, signal, ground as 3 wires directly back to the Arduino and not assume that I can ground the pot elsewhere that leads back to battery ground. Please confirm.

Definitely.

bigbangus:
Second, do you have any recommendations for specific buck converters for my <1A application? In the future, I plan to add a good amount of RGB LEDS (5As worth) that operate at 5V. Should I get 1 buck converter for the Arduino logic and then another one dedicated to my lighting down the road?

If you propose to use WS2812 strips with data fed from an Arduino, it is better to have a power supply adequate to regulate 5 V to the strips, and use that same source for the Arduino. This avoids problems due to one being powered when the other is not.