Thruster with new power supplies

We exchanged the original power supply: (see photo)

 

For two, also old but better power supplies:

 The difference lies in the current ratings. The Cenco power supply is only rated to provide 3 amps at 50 volts, whereas each Lab-Volt can handle up to 10 amps. The reason the two are wired in series is because the Lab-Volts can only provide up to 36 Volts. Neither power supply can provide for all of our needs in the thruster profile, so two in series is the way to go.
 

Like last time, the thrusters were immersed in water to simulate the load the will experience while in operation. Unlike last time, the DC-DC converter unit was also submerged for the duration of the test.

Instead of varying the voltage on this trial, I merely set the Lab-Volts to generate a potential of 48 Volts, and then connected the motors.

Here is a summary of the results:

Interesting differences compared to the previous experiment include that the sag voltage at the source is the same for each configuration (40V) and the current changes only marginally from two motors to three. If the resistance in the cable is approximately 5.5 Ohms, as was previously calculated, the power lost to the cable is 30, 38 and 43 Watts respectively.