BMS is short for Battery Management System. The function of the battery management system is to protect the safe use of the battery pack. The charging and discharging process of the battery pack ensures safety and prolongs the service life of the battery pack. With many electronic devices that require battery power, the use of rechargeable batteries has increased dramatically. To ensure that batteries are charged properly and optimized for their lifespan, battery management or fuel gauge systems have grown in parallel. The BMS battery management system is now complete. These battery management systems not only track the amount of power remaining in the battery, but also manage to charge, prevent battery damage from overcharging, and provide many other functions. As such, these battery management systems are an essential element in many of today’s rechargeable battery packs.
What are the main functions of BMS?
- Overcharge protection
Everyone should know that lithium batteries cannot be overcharged. Once overcharged, it will seriously lead to a short circuit inside the lithium battery cells, and there is a risk of explosion and fire.
The battery management system BMS has an overcharge protection function. When the voltage of the lithium battery rises to the overcharge protection value, the BMS will turn on the overcharge protection and cut off the charging, thus protecting the lithium battery from being overcharged. The charging voltage of ternary lithium monomer is 4.2V, and the single-cell overcharge protection voltage is 4.25V; the charging voltage of lithium iron phosphate monomer is 3.65V, and the single-cell overcharge protection voltage is 3.7V.
- Over-discharge protection
Over-discharge of lithium batteries will cause damage to the material structure and affect the life of lithium batteries. The lower discharge limit of ternary lithium monomer is 2.5V, and the single-cell over-discharge protection of BMS will be set to about 2.8V; the single-cell discharge limit of lithium iron phosphate is 2.0V, and the single-cell over-discharge protection of BMS will be set to about 2.5V.
The battery management system will control the lithium battery to work within a certain voltage range, neither too high nor too low. This can not only protect the cycle life of the lithium battery pack but also protect the lithium battery from the hidden danger of fire and explosion.
- Overcurrent protection, short circuit protection
When the load is abnormal, the lithium battery pack will be discharged with a large current, and even the positive and negative electrodes will be directly short-circuited. If this situation is not stopped, the lithium battery will continue to discharge at a large current, which will damage the cell, damage the components in the line, and cause a fire in severe cases. The BMS sets different current values and overcurrent protection delay time to control the abnormal current and cut off the discharge of the battery pack in time.
