Hi @ekivox,
Not sure what you’re referring to here, and your link doesn’t seem to work/go anywhere.
3 thrusters can use 3 times as much power as 1 thruster. When you’re testing one at a time then you make sure each thruster is working correctly, but it’s only testing whether the power supply is capable of running one thruster. When you then start running the ROV normally it uses multiple thrusters at once, and that can be too much power draw for the power supply to handle.
If you’re interested, I do a relatively detailed breakdown of power usage and conversion efficiencies for a surface-based power supply in this post. You can apply similar ideas to the cables, converters, and equipment that you’re using to get a sense of how much capacity your setup provides, and/or go in the opposite direction to determine how much capacity you need to provide to support full thrust of all your thrusters while still running the rest of your electronics 