In the STEM ROV : Propeller making, second post of the STM ROV production sharing series, it mentions that STEM thrusters generally use carbon brush motors due to cost and complexity considerations.The working voltage of 365 bursh motor is about 12 volts. Based on cost and portability, STEM ROV generally use 12V lead-acid batteries, which are also known as locomotive batteries on the market.
The power of the ROV thruster depends on the operating voltage that the carbon brush motor can finally obtain, because the speed of the carbon brush motor has a positive relationship with the operating voltage.Inferring from Ohm’s law, to obtain more operating voltage for carbon brush motors is nothing more than reducing other load losses and increasing the supply voltage.
Reducing other load loss is to confirm that the voltage transmission loss between the power supply and the ROV thruster can be reduced, for example, using a shorter network cable length.
To increase the voltage supply is to choose a battery with a higher voltage. Under the same conditions, the carbon brush motor of the ROV thruster can obtain a higher working voltage and higher speed. However, please confirm the upper limit of the operating voltage of the carbon brush motor used to avoid burning.
The following is the STEM ROV battery solution by ROV MAKER for reference.
In addition, we would recommend using an current meter to observe current variation of the STEM ROV propeller running in the air and water. The following is the current meter sold by ROV MAKER for reference.
The power consumption of electronic products is generated because current flows to provide the required electrical energy. The propeller will have more resistance in the water. If it is to maintain the same rotating speed as in the air, it will have to provide more electricity, and it will inevitably generate more current. As for the current difference in water or air, it is recommended that the user can observe it with an current meter.
Through the above suggestions, the maximum system current of the ROV can be observed. This can be used to evaluate whether the battery used can provide enough power and whether it needs to be replaced. Generally, lead-acid batteries will indicate the maximum current value, which is one of the discharge coefficients of the battery.
Through the understanding of Ohm’s law and the actual current measurement, it is quite helpful to improve the thrust of the STEM ROV.