The document discusses battery management systems (BMS). It explains that a BMS monitors and controls batteries to ensure safe and optimal use by performing functions like cell protection, charge control, state of charge and health determination, and cell balancing. It provides examples of BMS applications in intelligent batteries, battery storage power stations, and automotive battery management systems.

1. BATTERY
MANAGEMENT SYSTEM
NAME: - MRADUL SAXENA
ROLL NO.: - 198016

2. CONTENTS
• Why do we need Battery
Management System (BMS)?
• What is BMS?
• What does BMS do?
o Cell Protection
o Charge Control
o SOC Determination
o SOH Determination
o Cell Balancing
• Applications of BMS
o Intelligent Batteries
o Battery storage power
station
o Automotive BMS

3. WHY DO WE NEED BATTERY MANAGEMENT
SYSTEM(BMS)?
As humanity advances, need for portable electronics is increasing rapidly
which results in increase in demand of portable energy sources like
batteries(especially rechargeable batteries).
Now in order to use the energy from these portable sources( Batteries)
optimally the Battery Management Systems(BMS) are used.

4. WHAT IS BMS?
Battery Management System or BMS is the system designed to monitor the performance and
state of the battery and ensure that it works in its safe operating region.
In other words it can be said that “the basic task of a Battery Management System (BMS) is to
ensure that optimum use is made of the energy inside the battery powering the portable
product and that the risk of damage inflicted upon the battery is minimized.
This is achieved by monitoring and controlling the battery’s charging and
discharging process.”

5. BMS Block diagram

6. WHAT DOES BMS
DO?
The functions of BMS includes : -
• Cell Protection
• Charge Control
• SOC Determination
• SOH Determination
• Cell Balancing

7. CELL PROTECTION
Operating a battery outside of its specified
design limits will inevitably lead to the
failure of Battery.
Performance characteristics of battery are
limited by max current, max voltage, min
voltage, max temperature and min
temperature ratings.
BMS helps in keeping the battery to operate
under all these limits in the safe region of
operation.

8. CHARGE
CONTROL
The major cause of the battery damage is
implementation of improper charging
techniques.
Once a battery is fully charged, the charging
current has to be dissipated somehow. The
result is the generation of heat and gasses both
of which are bad for batteries.
To avoid this the BMS is used, it terminate the
charging when an upper limit of voltage known
as terminating voltage is reached.
The BMS also controls the rate of charge.

9. SOC
DETERMINATION
State of Charge (SOC) is defined as the available
capacity in a battery expressed as a percentage of
the actual (or estimated) rated capacity.
𝑆𝑂𝐶(%)
=
𝑒𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 − 𝑟𝑒𝑚𝑜𝑣𝑒𝑑 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦
𝑒𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦
× 100
Where capacity removed = 0
𝑡
𝐼 𝜏 𝑑𝜏
Where I is discharge current and t is time in hours
BMS continuously Monitors the state of charge of
the battery

10. SOH
DETERMINATION
State of Health (SOH) is the ability of a cell to
store energy, source and sink high currents, and
retain charge over extended periods, relative to its
initial or nominal capabilities.
SOH of battery is characterized by its power fade
and capacity fade.
Power fade: - The loss of cell power due to an
increase in cell impedance during aging is known
as power fade.
Capacity fade: - The gradual loss of capacity of a
secondary battery with cycling is known as
capacity fade.
BMS maintains the data of SOH and can report
user when the battery needs to be replaced.
RUL prediction curve of cell

11. CELL BALANCING
In multi-cell battery chains small differences
between cells due to production tolerances
or operating conditions tend to be magnified
with each charge / discharge cycle. Weaker
cells become overstressed during charging
causing them to become even weaker, until
they eventually fail causing premature
failure of the battery. Cell balancing is a way
of compensating for weaker cells by
equalizing the charge on all the cells in the
chain and thus extending battery life.

12. APPLICATION OF BMS
• INTELLIGENT BATTERIES
• BATTERY STORAGE POWER STATION
• AUTOMOTIVE BMS

13. INTELLIGENT
BATTERIES
Intelligent Batteries or smart batteries are
rechargeable batteries with built in Battery
Management system.
A smart battery can measure voltage and
current, and deduce charge level and SoH (State
of Health) parameters, indicating the state of the
cells. Also a smart battery can communicate
with a smart battery charger and a "smart
energy user" via the bus interface. A smart
battery can demand that the charging stop,
request charging, or demand that the smart
energy user stop using power from this battery. VR420 Lithium Ion Smart Batteries
Developed by Accutronics

14. BATTERY
STORAGE POWER
STATION
A battery storage power station is a type of energy
storage power station that uses a group of batteries
to store electrical energy. Battery storage is the
fastest responding dispatchable source of power on
grids, and it is used to stabilize grids, as battery
storage can transition from standby to full power
within milliseconds to deal with grid failures.
An essential responsibility of managing such
installations is to know the status of the battery and
whether it can be relied upon to support its load
during an outage. For this it is vital to know the
SOH and the SOC of the battery. BMS can easily
maintain this data for such installations. Tehachapi Energy Storage Project, Tehachapi, California

15. AUTOMOTIVE BMS
• Automotive battery management is much more demanding than the previous
two applications. As it has to interface with a number of other on board
systems, it has to work in real time in rapidly changing charging and
discharging conditions as the vehicle accelerates and brakes, and it has to
work in a harsh and uncontrolled environment.
• Some of the functions of a BMS suitable for a hybrid electric vehicle are as
follows:
• Providing information on the State of Charge (SOC) of the battery. This
function is often referred to as the "Fuel Gauge" or "Gas Gauge “.
• Predicting the range possible with the remaining charge in the battery (Only
EVs require this)
• Providing the optimum charging algorithm for charging the cells.
• It can determine the vehicle's desired operating mode, whether it is
accelerating, braking, idling or stopped, and implement the associated
electrical power management actions.