A battery management system (BMS) is an electronic regulator that monitors and controls the charging and discharging of rechargeable batteries. Battery management systems of various types are used in most devices that use rechargeable batteries. They are also common in datacenters, where UPS (uninterruptable power supplies) keep servers online. Cars, especially electric, include battery management systems, as do everyday portable devices like MP3 players and smartphones. Battery management systems may be as simple as electronics to measure voltage and stop charging when the desired voltage is reached. At that point, they might shut down the power flow; in the event of irregular or dangerous conditions they might issue an alarm. A more complex BMS monitors many factors that affect battery life and performance as well as ensuring safe operation. They may monitor one-cellor multi-cell battery systems. Multi-cell systems may monitor and control conditions of individual cells. Some systems connect to computers for advanced monitoring, logging, email alerts and more. Factors monitored and controlled by battery management systems include: (1) Main power voltage. (2) Battery or cell voltage. (3) Charging and discharge rates. (4) Temperatures of the batteries or cells. (5) Battery and cell health. (6) Coolant temperature and flow for air or liquid cooling