The HV-battery of an electric car is called a battery pack (short battery). A battery pack consists of individual battery modules, which consist of individual cells. These cells are monitored by the so-called BMS (Battery Management System). It is the brain of a battery pack and monitors every single cell. The BMS is what makes the battery so durable and is the reason why you can not compare the battery pack of an electric car with the bare cell of a cell phone.
The most important function of the BMS is to ensure that not a single cell is over- or deep-discharged, it also ensures that each cell is neither too hot nor too cold. These are just the most important things of the BMS, in the background it does even more so that we don't have to care about the battery. The battery pack is then packed in a proverbial armored case.
