Hi guys . My name is Hoang & I’m a student in Viet Nam . I have 1 question about the power for ROV system. Our team used to designed a ROV with battery outside the system connecting by a tether. But when it comes to the water. The power decreased and out of battery quickly. So we re-design the system by putting the battery into the system without any tether . I need some help about this idea . What is the circuit we will make ?? Have any solutions on the Internet before ?? . Thanks !!!