6S Battery Protection Circuits

What is Battery Management System or BMS?

 

Battery Management System – Battery Management System (BMS) is the battery's safety system and is responsible for keeping battery conditions (such as voltage, current & temperature) within safe limits.

 

The level of protection depends on both the requirements of the battery chemistry and the complexity of the BMS itself. Batteries with primitive chemistries such as lead acid and nickel cadmium are resistant to overcurrent and overvoltage situations due to their high internal resistance and high self-discharge levels. Most of the time there is no need for protection other than a fuse.

 

However, while closed-type Lead Acid (SLA) Batteries, Valve Regulated Lead Acid (VRLA) Batteries and Nickel Metal Hydride (Ni-MH) batteries provide higher efficiency, they are more vulnerable to overvoltage, undervoltage, overcurrent and extreme temperature conditions. It is therefore important to monitor these batteries for specified conditions during operation.

 

 

Battery Management System in Lithium Ion Batteries

 

Lithium-based batteries are much more sensitive to operating conditions than all other batteries. Although the other batteries described may be damaged, they can often overcome short-term disturbances and regulate themselves. On the other hand, lithium batteries are very intolerant in terms of voltage & temperature limits. For example, even if the maximum charging voltage of an SLA, VRLA, or Ni-MH cell is exceeded by 100 millivolts, the cell will self-discharge, release some heat, and possibly continue operating with a small loss of capacity. If the same amount of overcharging is attempted in a lithium cell, the cell will undergo a destructive reaction, heating up and eventually breaking down.

 

 

The Battery Management System is generally responsible for MAINTAINING the safe conditions of the battery. Since each battery type has different limits and tolerances, battery management systems must comply with the same limits and tolerances.

 

 

Battery Protectors

 

The simplest form of BMS, also known as a "Battery Saver", takes the battery's cell voltages and battery current and compares them to predefined limits. Any exceedance results in battery disconnection. This function is usually provided by simple analog comparator integrated circuits. Disconnection It can be easily achieved using a MOSFET group.

 

Battery Protectors are used in widespread application areas, from small household appliances and hand tools to small vehicles such as electric bicycles and electric scooters. The main function of this type of Battery Savers is to provide the basic conditions for battery protection, but they cannot provide the most critical features listed below.

 

Balancing the cells to the same charge level

Calculating the battery's state of charge (SOC) and state of health (SOH)

 

Presenting battery information through a communication interface

 

 

6S 12A 25.5V BMS Lithium Battery Protection Circuit

 

 

Features

 

short circuit protection

Overcharge - discharge protection

Lampshift maximum discharge current: 15A

Instantaneous discharge current: 25A

Charging voltage: 25.5V

Charging current: 12-15A (MAX)

Overcharge detection voltage: 4.28 ± 0.05V

Overcharge protection delay: 0.1S

Overcharge output voltage: 4.08±0.05V

Over-discharge detection voltage: 2.55 ± 0.08V

Over-discharge detection delay: 0.1S

Over-discharge release voltage: 2.9±0.1V

Overcurrent detection voltage: 150mV

Overcurrent detection delay: 9mS

Overcurrent protection current: 30±3A

Main circuit conduction resistance: ≤ 20mΩ

Working current: ≤ 30uA

Sleep current (battery over-discharge) ≤ 10uA

Temperature range: -30 ~ +80°

 

 

 

Wiring Diagram

08.06.2024