I found the tips presented in the video below are applicable when dealing with other type of electronic devices and even more applicable when customizing old CPU power supplies for our battery chargers.
https://www.youtube.com/watch?v=VK_K6fp4BIk
Power Cable Quality may compromise your Safety !!!!. A video on How to Test for Bad Ground Connections
https://www.youtube.com/watch?v=sqEgsZitkoo