EVs have two batteries, believe it or not! One is the big traction battery, and the other is a smaller 12-volt battery that needs periodic replacement (basically the same battery as any gas-powered car uses to run the lights and radio, but EVs have lots of computers and other equipment that run while the car is parked to manage the battery, process over-the-air software updates and more).
Your owner's manual or manufacturer's customer service hotline is the best resource for information on getting the most out of your car's big traction battery. The general consensus among EV owners is to not charge to 100 percent unless you're going on a long trip, to not let the battery discharge below 20 percent too often, and to only occasionally use a fast charger. Also, EV owners would remind you that modern EV batteries are designed with you and your busy, real-world life in mind! Being hyper-careful will likely not make a huge difference in battery life and performance over the long-term.