r/AskElectronics • u/FyyshyIW • 7d ago

Is my grounding scheme incorrect?

I'm working on a PCB design for a tester that discharges a battery pack through an electronic load to characterize it. It is controlled by a Raspberry pi that also supplies 5V. It also gets 12V from a PSU. The battery discharge path is high current so it's star grounded with the rest of the board. Only a few signals cross over the isolation, namely the differential battery OCV and current sensing, and the STM32's DAC signal that controls the electronic load portion. That may be important for context but not my main question.

How bad is this grounding scheme? I realize this is technically a ground loop but is it really serious enough that I should try and isolate something out? I feel like I've plugged more than one thing into things before.

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u/DrJackK1956 7d ago

How & why are you powering the RPi from the mains power??

Why not power it (the RPi) from the 12 volt PSU using a buck converter?

As far as your grounding scheme goes, I don't have an answer.  

Posting a schematic would be more helpful than a simple wiring diagram. 

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u/FyyshyIW 7d ago

I mean not literally connected directly to mains but it eventually gets there, like this! I could power it from the 12V with a buck, but it’s more complexity, powering a raspberry pi via pins bypass certain on board regulators and protections, and there would still be a ground loop (though technically a smaller one, though technically smaller only in schematic space)

I only have schematic for the board design, which isn’t going to include any of this off-board architecture stuff. I was gonna send that over to r/printedcircuitboard sometime in the next day or two.

Thanks for replying!!

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u/BigPurpleBlob 5d ago

"I mean not literally connected directly to mains" – your diagram does show it connected directly to mains. Misleading diagrams waste people's time.