What does a BMS/PCM do for batteries?

A lithium battery is mainly composed of two parts: cells and BMS (Battery Management System).

Lithium cells consist of the anode, separator, cathode,electrolyte, and the materials are rolled or laminated to make into the cells.

BMS: used to protect the lithium battery,as a safeguard for the lithium-ion batteries. The batteries can work properly only under the protection of the BMS. The main role of the protection board are: protecting the battery from over discharging and charging; over current and short circuit protection.

Lithium battery BMS is to protect each series of lithium battery when charging and discharging. Fully charged can ensure that voltage difference between the individual cells is less than the set value (usually ± 20mV). Achieving the battery charged in balance, which effectively improve charging efficiency in series. At the same time, the BMS detects whether the individual battery are in the situation of overvoltage, undervoltage, overcurrent, short circuit, over temperature to protect and extends the battery life. The undervoltage protection prevents each single cell from being damaged during discharging.

Lithium battery BMS is mainly composed of protection IC (overvoltage protection) and MOS tube (over-current protection), which are safety devices to protect the lithium battery cell . With large discharge current, low internal resistance, long life, no memory effect, lithium batteries are widely used.When using lithium-ion battery,overcharge,over discharge, short circuit should be strictly prohibited, otherwise it will cause fire, explosion and other fatal shortcomings. Therefore, when using rechargeable lithium batteries, it must  have BMS to protect the safety of batteries.

How does a BMS work?

Over discharge protection: When the battery is running out , the BMS will be shut down at the minimum value of the voltage for over-discharge protection.

Overcharge protection: When the product is charging, the BMS will automatically power off at the maximum value of voltage and display full charged status for overcharge protection.

Short circuit protection: When the battery is in short circuit, the BMS will automatically shut down for several milliseconds to cut off the circuitry for short circuit protection to avoid accident.

Overcurrent protection: When the battery is discharging, the BMS will shut down automatically at the maximum value of current, which may differ from product to product.

In short, the protection board on the lithium battery pack plays a vital role.In order to ensure to delivery high-quality battery pack, KOK Power always use high quality BMS with protection board IC and MOSfet made from the world’s first class brands such as TI, IR, Seiko,etc.