A battery management system (BMS) is any electronic system that manages a chargeable battery (cell or battery pack), like by protective the battery from operational outside its safe operating area[clarification needed], watching its state, conniving secondary information, coverage that information, dominant its setting, authenticating it and / or equalisation it.
A battery pack designed along with battery management system with Associate in Nursing external communication information bus may be a sensible battery pack. a wise battery pack should be charged by a smart device.
A BMS could monitor the state of the battery as depicted by numerous things, such as:
Voltage: total voltage, voltages of individual cells, minimum and most cell voltage or voltage of periodic faucets
Temperature: average temperature, agent intake temperature, agent output temperature, or temperatures of individual cells
State of charge (SOC) or depth of discharge (DOD), to point the charge level of the battery
State of health (SOH), a variously-defined measuring of the remaining capability of the battery like of the first capacity
State of power (SOP), the number of power out there for an outlined amount given this power usage, temperature and alternative conditions
State of Safety (SOS)
Coolant flow: for air or fluid cooled batteries
Current: current in or out of the battery
Electric Vehicle Systems: Energy Recovery
The BMS also will management the recharging of the battery by redirecting the recovered energy (i.e.- from regenerative braking) back to the battery pack (typically composed of some batteries, every composed of some cells).
Additionally, a BMS could calculate values supported the on top of things, such as:
Maximum charge current as a charge current limit (CCL)
Maximum discharge current as a discharge current limit (DCL)
Energy [kWh] delivered since last charge or charge cycle
Internal electric resistance of a cell (to verify circuit voltage)
Charge [Ah] delivered or hold on (sometimes this feature is termed Coulomb counter)
Total energy delivered since initial use
Total operational time since initial use
Total variety of cycles
The central controller of a BMS communicates internally with its hardware operational at a cell level, or outwardly with high level hardware like laptops or Associate in Nursing HMI.[clarification needed]
High level external communication are straightforward and use many methods:
Different types of serial communications.
CAN bus communications, usually utilized in automotive environments.
DC-BUS – Serial communication over power-line
Different types of Wireless communications.
Low voltage centralized BMSs largely don’t have any internal communications. They live cell voltage by resistance divide.
Distributed or standard BMSs should use some low level internal cell-controller (Modular architecture) or controller-controller (Distributed architecture) communication. These kinds of communications are troublesome, particularly for top voltage systems. the matter is voltage shift between cells. the primary cell ground signal could also be many volts beyond the opposite cell ground signal. except for software system protocols, there are 2 acknowledged ways that of hardware communication for voltage shifting systems, Optical-isolator and wireless communication. Another restriction for internal communications is that the most variety of cells. For standard design most hardware is restricted to most 255 nodes. for top voltage systems the seeking time of all cells is another restriction, limiting minimum bus speeds and losing some hardware choices. price of standard systems is very important, as a result of it should be admire the cell value. Combination of hardware and software system restrictions results to be some choices for internal communication:
Isolated serial communications
wireless serial communications
Battery affiliation to load circuit
A BMS might also feature a precharge system permitting a secure thanks to connect the battery to totally different masses and eliminating the excessive inflow currents to load capacitors.
The affiliation to masses is often controlled through magnetic force relays referred to as contactors. The precharge circuit is either power resistors connected asynchronous with the hundreds till the capacitors are charged. instead, a switched mode power provide connected in parallel to masses is wont to charge the voltage of the load circuit up to level shut enough to battery voltage so as to permit closing the contactors between battery and cargo circuit. A BMS could have a circuit which will check whether or not a relay is already closed before precharging (due to fastening for example) to stop inflow currents to occur.