Hi there, so when anodizing metals a psu unit is used to fine tune the voltage to obtain different colour shades. Batteries can be used but it will max out at some point and a pain to set up. The psu unit allows for more colours. When anodizing ,as you may know, you need to dip your piece in a solution with a lead from the- to a cathode and + to the piece. When you adjust the voltage to obtain the desired colour the amp should go up briefly and get down again to almost 0 when anodizing is complete. The process is pretty fast just few minutes. On my unit the amp doesn’t go back down or extremely slowly. So the piece is not changing colour. Is this helping? Thanks