Reposted with permission from RAHS Green Energy Team
Heading into the 2022 Solar Car competition, the team is making big upgrades to the current car, such as a new suspension system, solar array, and battery pack. The battery pack, in particular, will allow the car to store more energy and last longer on the track. There are many steps involved in making a battery pack. You need to select and order the batteries, garner materials for the battery pack, assemble them, and build a battery box for it.
The first step in creating a battery pack is battery selection; it is imperative to be aware of several different factors such as the capacity of each cell, the voltage of each cell, the arrangements, and the number of cells required to fit our specifications. To keep track of all this data, we created a spreadsheet. All we have to do is enter two numbers (the nominal voltage and nominal capacity) and the sheet calculates the capacity of the battery pack per arrangement and ranks them. Our goal is to find a battery arrangement that gets as close to 5000 Watt-hours as possible, uses a minimal amount of cells, is lightweight, and is reliable.
After selecting the battery, we must look for a good supplier. One member of the project, Thomas Kebede, notes that a good supplier “will help us make sure the batteries come at a reasonable cost, and without damage.” Sites such as Voltaplex and 18650 Battery Store are examples of what we consider to be reliable suppliers.
Aside from selecting and ordering the batteries, we must obtain the materials required to build the battery pack. We need spacers to arrange the cells correctly; we need ribbons – copper or nickel strips – which will connect the cells; finally, we need a way to attach the ribbons to the batteries. We will use a soldering iron which we have found to be the most reliable despite the risk of damaging the cells. To combat this risk, we will cool the area using compressed gas.
Lastly, we must have a battery box to house the battery pack. This keeps the battery cool, protecting the battery from the outside and protecting us from its high voltage. The battery box is made out of carbon fiber and fiberglass.