SmartDive ROV: Development of the Battery

Battery is one of the most important elements of the ROV. It provides power to the entire device. But you can't just buy a suitable battery in a store. You could do it, but its parameters will not be optimal for the device. In order for the battery to work as long as possible and fit into the device, it must be made to order or produced independently.

In this article, we will tell you how we developed and produced our own batteries for the SmartDive ROVs.

The abbreviation 4S6P means that we connect 6 cells in parallel into 4 assemblies and connect all these assemblies in series. In total, it takes 24 cells to create one battery pack.

The cells can differ in capacity and maximum output current. Since the SmartDive remote-controlled underwater vehicle can operate from 2 to 6 engines, LED lights and various attachments at the same time, we use high-current cells with a large capacity.

It all starts with cells. Cells are the minimum, but the main element of the battery assembly, they can also be called 18650 batteries. From individual cells, we assemble 4S6P batteries. Each such cell has its own parameters of voltage, stored power and maximum output current. The more cells are assembled in parallel, the greater the capacity and the output current. If we assemble the batteries in series, the voltage of the common assembly changes, but the capacity and output current remain the same.

Assembling the cells together is quite a task, because they are afraid of overheating, require certain assembly skills and a certain type of equipment. Another difficulty is to find a contractor whose quality and cost of work would suit us completely. The cost of welding the first battery we ordered was almost the same as the cost of all 24 cells. Therefore, we wondered how to do it ourselves and purchased a spot welding machine and nickel tape, which has a high electrical conductivity. After we adjusted the welding conditions, we ordered nickel sheets, developed the apertures necessary to connect the cells with a continuous layer of nickel, and ordered their laser cutting.

The first version of the battery was non-removable: the battery bulb did not detach from the frame during charging. We developed a variant of a quick-detachable battery later. The battery flask can now be easily removed from the body of the device and put on charge, replacing it with another flask. This innovation allows you to use the underwater vehicle without interruptions for charging.

It takes 4-5 hours to recharge the batteries that we install on our ROVs. The operating time of the SmartDive battery is up to 4 hours. It depends on working conditions of the ROV: the strength of the current, the illumination of the water column and other factors.

The tightness of the space in which the battery should be located is provided by 4 seals along the diameter of the flask and 1 end seal in each lid covering the flask from both sides.

The SmartDive ROV batteries come in different capacities — 18 A*h or 36 A*h with a rated voltage of 14.8 V and a maximum output current of 90 or 180 A.

As a result, we have developed and established the production of reliable batteries that fully meet our needs.