The main purpose of a BMS is to make sure that the battery is used efficiently while supplying the load and to prevent damage to the battery.
This can be achieved by control and monitoring of charging and discharging process of the battery. Thus, BMS implements control and monitoring of battery charging and discharging regime.
Main Algorithms
There are main algorithms to check and control the links in the energy chain. I have listed these below:
- Charging Algorithm:
These tracks and controls the charging by interrupting it when the battery is full. Overcharging leads to increase in battery temperature. This leads to damage of the battery decreasing the capacity and useful cycles. Proper charging algorithms are necessary for efficient battery usage. - Discharge Algorithm:
This controls the magnitude of the discharge current. It makes sure that that the discharge current does not exceed the rated/set current limit of the battery discharge current. Also, it isolates the battery from the load if the operating voltage falls below safe limits thus preventing permanent damage to the cell due to over discharge. - Algorithms to determine the State of Charge (SOC):
This algorithm is used as a feedback to the charging algorithm to end the charge and discharge cycles. - Algorithm to control DC-DC converter(Charger): This is used to power the load with minimum required voltage.
Objectives of Battery Management System:
- Battery Management – The optimum use of the battery
- Power Management – Minimize power dissipation and proper power distribution.
- Energy management – Efficient energy conversion
- Keep track of SOC – The SOC is used to control charging and discharging.
Therefore, the BMS integrates two functions for monitoring and control. The monitoring unit collects the data specific to the battery such as the charging or discharging currents, SoC, number of cycles , and depth of discharge. A more detailed description and useful tools for and Effective Capacity Calculator and Battery Life Cycle Calculator can be found on Everspring Website. While the control unit is the one which implements intelligence to the system by acting on the charging and discharging processes based on the data collected by the monitoring unit.
In summary
it is very important to match a specific BMS to your battery cells type and the target storage application if the battery cell life are to be prolonged. At Everspring, we have been assisting our partners to development and support such setup for large format Lithium Ion cells since 2001.