I am using the Ardusub system on a ROV for the MATE Competition with 6 thrusters in the standard vectored orientation, supplying power through a 50ft tether with 8AWG silicone wire. The electronics inside the enclosure are similar to those on the BlueROV2 but without a Fathom tether interface board. We were having trouble with the power unexpectedly cycling at our last pool test after about an hour and a half of continuous time in the water. After some testing we found out that it also cycles when switched between depth hold and manual mode very quickly. It doesn’t just cycle the power to the Pixhawk or Pi, but cycles the power to the entire system.
The power supply enters the control box and is distributed via a double bus board, with one of the connections coming off of it being the wires to the robot. There are separate systems connected to the same bus bar that cycle at the same time, so I’m guessing there is a power surge through the entire tether. However, only 12V is used and the current for each thruster is limited through PWM limits. Each thruster should only be able to draw 2A at a time because of these limits. There is a 25A fast-blow fuse before the power source, and this is still perfectly intact, so it isn’t surging like crazy. Does anyone know how to fix this or should I just drive carefully and pull the robot out of the water occasionally?
UPDATE: Did some voltage tests and found that the power supply box we were using that is said to max out at 13.8V was jumping all the way to 22V when we switched modes. Tried doing the same tests with a 12V battery and could not replicate the power cycling. We are using the Powerwerx 30A Box, and have had it for about 3 years now and I’m currently trying to find out what caused this problem.