USB powerpack

Hi all,
I’m making a project using a 5v power pack for the Arduino .It supplies power and charges via two 5v USB connectors.
I have a PCB made( !!) that uses this and enables me to use to power the project from the pack or switch ( when the pack is flat) to run from the charger (whilst also charging the pack ) .
At a late date I’ve discovered the 0v rail is not common to the input and output side of the pack ( in fact if you connect both 0v lines it won’t work at all). So my circuit won’t work ( I only switch the +ve connections to disconnect the pack or switch the charger).
Does anyone know if all power packs are like this or know of one that isn’t? I need , because of my circuit, a pack with a common 0v line. If I can buy a different pack , it’s the easy Fix !


Can you post a schematic and a PCB pattern image please?

Tom... :slight_smile:

This DIY power bank has common grounds. Just insert 4x 18650 batteries.

Thanks Riva , anyone else seen/have anything ? ( might need More capacity (as in a lipo pack).

Good link that , and a good start - worth a punt.

  • I don’t think posting the PCB will help , I was just trying to explain why I needed the common ground .