EV Battery
Management
For Naan Mudhalvan
Module 3:
Battery Safety and
Thermal
Management
For Naan Mudhalvan
Module 3
Part 2: Protocols and
Strategies
Upholding Safety: Reporting
Standards and Protocols for
EV Batteries
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Safety Protocols for EV Batteries
Introduction
The safety of electric vehicle (EV) batteries is of paramount importance, necessitating
stringent protocols and reporting standards.
In this exploration, we will delve into the key safety protocols established for EV
batteries, providing detailed explanations, examples, and visual representations to
ensure a comprehensive understanding.
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Safety Protocols for EV Batteries
1. State-of-Charge (SoC) Limits
Explanation
• Establishing upper and lower limits for the State of
Charge to prevent overcharging or deep
discharging, both of which can compromise battery
safety.
• Undefined SoC limits cause overcharging, which
can lead to thermal runaway, and deep
discharging, which can compromise battery health
and safety.
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Safety Protocols for EV Batteries
1. State-of-Charge (SoC) Limits
Examples
1. Setting a SoC range of 20-80% for daily use to extend
battery life.
2. If an EV's battery has a maximum SoC limit of 90%, the
BMS will ensure that charging ceases once this limit is
reached.
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Safety Protocols for EV Batteries
2. Thermal Management Thresholds
Explanation
• Defining temperature limits within which
the battery should operate to prevent
overheating or excessive cooling.
• Establishing temperature limits prevents
overheating during high-demand situations
and ensures that the battery maintains
optimal performance.
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Safety Protocols for EV Batteries
2. Thermal Management Thresholds
Examples
1. The BMS actively manages cooling or heating
systems to maintain a temperature range of 25°C to
40°C during operation.
2. Setting a threshold of 25°C to 40°C for optimal
battery performance.
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Safety Protocols for EV Batteries
3. Overcurrent Protection
Explanation
• Implementing safeguards against
excessive current flow that could lead
to overheating or short circuits.
• Overcurrent protection mechanisms,
such as fuses, disconnect the battery
during instances of excessive current
flow, preventing overheating and
damage.
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Safety Protocols for EV Batteries
3. Overcurrent Protection
Examples
1. A fuse in the battery circuit disconnects
when the current exceeds a safe limit.
2. Incorporating fuses and circuit breakers to
disconnect the battery during overcurrent
events.
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A Video: Electric Shock Safety
Source Credit:
EV Quotient
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Safety Protocols for EV Batteries
4. Overvoltage Protection
Explanation
• Establishing measures to prevent
the battery voltage from exceeding
safe levels.
• Preventing overvoltage protects the
battery from damage and ensures
safe charging and discharging.
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Safety Protocols for EV Batteries
4. Overvoltage Protection
Examples
1. A voltage limiter disconnects the charging process
when the voltage surpasses a predefined threshold.
2. Utilizing voltage limiters to disconnect charging when
the voltage surpasses a predefined threshold.
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Safety Protocols for EV Batteries
5. Emergency Shutdown Procedures
Explanation
• Defining protocols for emergency situations,
such as accidents or malfunctions, to safely
disconnect the battery.
• In emergency situations, having a clear
shutdown protocol ensures the rapid and
safe disconnection of the battery.
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Safety Protocols for EV Batteries
5. Emergency Shutdown Procedures
Examples
1. An emergency shutdown switch allows for the
immediate disconnecting of the battery in case of an
accident.
2. Example: Implementing a manual or automatic
emergency shutdown switch.
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Safety Protocols for EV Batteries
6. Fire Suppression Systems
Explanation
• Incorporating fire suppression systems to
mitigate the risk of fire in case of thermal
runaway.
• Fire suppression systems, including fire-
resistant materials and extinguishing
agents, mitigate the risk of fire during
thermal runaway.
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Safety Protocols for EV Batteries
6. Fire Suppression Systems
Examples
1. Fire-resistant materials line the battery compartment,
and extinguishing agents activate in the event of
thermal runaway.
2. Installing fire-resistant materials and extinguishing
agents within the battery compartment.
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Safety Protocols for EV Batteries
7. Cell Balancing Protocols
Explanation
• Enforcing procedures for regular cell
balancing to ensure uniform performance
and prevent capacity discrepancies.
• Regular cell balancing prevents capacity
discrepancies, ensuring uniform
performance and extending battery life.
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Safety Protocols for EV Batteries
7. Cell Balancing Protocols
Examples
1. The BMS initiates periodic cell balancing during
charging cycles to equalize the charge among
cells.
2. Implementing periodic cell balancing during
charging cycles.
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Safety Protocols for EV Batteries
8. Impact and Vibration Protection
Explanation
• Implementing measures to protect the battery
from physical impacts and vibrations during
accidents or harsh driving conditions.
• Protective measures safeguard the battery
from physical impacts and vibrations, reducing
the risk of damage.
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Safety Protocols for EV Batteries
8. Impact and Vibration Protection
Examples
1. The battery housing incorporates shock-absorbing
materials to minimize the impact of collisions or
harsh driving conditions.
2. Designing the battery housing with shock-
absorbing materials.
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Safety Protocols for EV Batteries
Conclusion:
The stringent safety protocols and reporting
standards for EV batteries are a testament to the
commitment to user safety, public trust, and the
widespread adoption of electric vehicles. By
meticulously defining and implementing these
protocols, the industry ensures that EVs deliver
not only on efficiency and sustainability but also
on the highest standards of safety.
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A Case Study:
Chevy Bolt’s Battery Recall
and Safety Protocols
A Case Study:
Chevy Bolt’s Battery Recall and
Safety Protocols
Introduction to General Motors
• General Motors is an American
multinational corporation that designs,
manufactures, markets, and distributes
vehicles and vehicle parts.
• General Motors is the parent company of
Chevrolet, which produces the Chevrolet
Bolt EV.
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A Case Study:
Chevy Bolt’s Battery Recall and
Safety Protocols
Chevy Bolt’s Battery Recall
• In 2020, General Motors faced a significant
challenge when reports of battery-related
fires in Chevrolet Bolt EVs prompted a large-
scale recall.
• The recall affected over 1,40,000 vehicles
worldwide.
• The recall highlighted the critical importance
of effective safety protocols in electric
vehicles.
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A Case Study:
Chevy Bolt’s Battery Recall and
Safety Protocols
Challenges and Problems
• The battery-related fires in Chevrolet Bolt EVs
posed a significant challenge for General
Motors.
• The recall affected over 140,000 vehicles
worldwide, leading to significant costs and
reputational damage.
• The recall also highlighted the dynamic nature
of battery safety and the need for automakers to
continuously refine and update safety protocols
to address emerging challenges.
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A Case Study:
Chevy Bolt’s Battery Recall and
Safety Protocols
Overcoming Challenges
• General Motors implemented comprehensive
safety measures to address the battery-related
fires in Chevrolet Bolt EVs.
• General Motors worked closely with LG Chem to
identify the root cause of the battery-related fires.
• General Motors implemented comprehensive
safety measures, including software updates to
limit charging capacity and thermal management
adjustments to prevent overcharging.
• General Motors also worked with regulatory
agencies to ensure that the recall was conducted
effectively and efficiently.
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A Case Study:
Chevy Bolt’s Battery Recall and
Safety Protocols
Takeaways
• The Chevy Bolt’s battery recall underscores the
critical importance of effective safety protocols in
electric vehicles.
• The recall highlights the dynamic nature of battery
safety and the need for automakers to continuously
refine and update safety protocols to address
emerging challenges.
• The recall also highlights the importance of
collaboration between automakers and suppliers to
ensure the ongoing safety of electric vehicles.
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Quiz Time!
Safety Protocols
Quiz
Question 1
What is the primary purpose of defining State-of-Charge
(SoC) limits in EV battery management?
A) To maximize energy density
B) To prevent overcharging and deep discharging
C) To accelerate charging speed
D) To enhance overall battery aesthetics
Answer: B)
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Quiz
Question 2
What does the Emergency Shutdown Switch in an
electric vehicle provide?
A) Improved fuel efficiency
B) Immediate battery disconnect in emergency situations
C) Enhanced regenerative braking
D) Faster acceleration response
Answer: B)
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Quiz
Question 3
How does overcurrent protection safeguard EV
batteries?
A) Enhances energy transfer efficiency
B) Initiates emergency shutdown procedures
C) Disconnects the battery during excessive current
flow
D) Boosts acceleration performance
Answer: C)
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Quiz
Question 4
What role does cell balancing play in EV battery
management?
A) Reduces charging time
B) Maximizes energy density
C) Ensures uniform performance and extends
battery life
D) Enhances regenerative braking efficiency
Answer: C)
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Quiz
Question 5
Why are impact and vibration protection measures
implemented in EV batteries?
A) To increase overall vehicle speed
B) To protect the battery from physical damage
during accidents or harsh driving conditions
C) To improve regenerative braking performance
D) To reduce energy consumption
Answer: B)
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Mastering Heat: Thermal
Management Strategies to
Prevent Overheating in EV
Batteries
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Thermal Management Strategies:
Introduction
In the realm of electric vehicles (EVs), effective thermal management is crucial
to prevent overheating, enhance battery performance, and ensure the longevity
of energy storage systems.
This section aims to enlighten 6th-semester engineering students about various
thermal management strategies employed in EVs, providing definitions,
explanations, and visual representations for each.
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Thermal Management Strategies
1. Active Liquid Cooling:
- Definition: Active liquid cooling involves - Explanation: Coolant absorbs heat from the battery
circulating a coolant, often a liquid with cells and carries it away, maintaining optimal
high thermal conductivity, through operating temperatures.
channels or plates in direct contact with
battery cells to dissipate heat.
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Thermal Management Strategies:
2. Passive Air Cooling:
- Definition: Passive air cooling relies on - Explanation: Heat is dissipated through air
natural convection or forced airflow to circulation around the battery pack, promoting
dissipate heat from the battery pack simplicity and energy efficiency.
without the use of additional cooling
systems.
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Thermal Management Strategies:
3. Phase Change Materials (PCM):
- Definition: Phase Change Materials
absorb and release thermal energy
during phase transitions (solid to liquid,
and vice versa), acting as a thermal
buffer to regulate temperature.
- Explanation: PCM stabilises battery
temperature by absorbing heat during high
temperatures and releasing it during low
temperatures.
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Thermal Management Strategies:
4. Direct Air Cooling:
- Definition: Direct air cooling involves - Explanation: Fans force air through the battery
utilising fans or blowers to directly pack, removing heat and maintaining an optimal
circulate ambient air over the temperature range.
battery pack to dissipate heat.
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Thermal Management Strategies:
5. Thermal Interface Materials (TIM):
- Definition: Thermal Interface Materials - Explanation: TIM fills gaps and irregularities
enhance heat transfer between battery between components, improving the contact and
cells and cooling elements, ensuring heat dissipation capabilities.
efficient thermal conductivity.
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Thermal Management Strategies:
6. Refrigerant-Based Cooling:
- Definition: Refrigerant-based cooling - Explanation: Refrigerant circulates through the
employs a refrigeration cycle, similar to system, absorbing heat from the battery cells and
that in air conditioning systems, to releasing it outside, maintaining temperature
absorb and release heat within the control.
battery pack.
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Thermal Management Strategies:
7. Thermal Spreaders:
- Definition: Thermal spreaders, often - Explanation: Heat generated in specific areas is
made of materials with high thermal spread across the thermal spreader, preventing
conductivity, distribute heat evenly localized overheating.
across the battery pack.
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Thermal Management
Strategies:
8. Active Phase Change Cooling:
- Definition: Active phase change cooling - Explanation: External control initiates phase
utilizes phase change materials that transitions, absorbing or releasing heat as needed
actively change state through external to regulate battery temperature.
stimuli, such as electrical or magnetic
fields, to manage temperature.
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Case Study
Activity:
Nissan Leaf's Thermal
Management Evolution
Case Study Activity:
Nissan Leaf's Thermal Management
Evolution
Activity to be done at home
Conduct a bit of research on the above-mentioned case study topic.
We will discuss this for a few minutes tomorrow.
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Quiz Time!
Thermal Management Strategies
Quiz
Question 1
How does passive air cooling dissipate heat from the
battery pack?
A) Utilizing a refrigeration cycle
B) Forcing air through the battery pack
C) Natural convection and conduction
D) Enhancing heat transfer with thermal spreaders
Answer: C)
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Quiz
Question 2
What role do Phase Change Materials (PCM) play in an
electric vehicle battery pack?
A) Increase electrical conductivity
B) Stabilize battery temperature by absorbing and
releasing thermal energy
C) Distribute heat evenly across the battery pack
D) Actively change state through external stimuli
Answer: B)
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Quiz
Question 3
In direct air cooling, what is the main purpose of fans or
blowers?
A) Absorbing heat from the cells
B) Initiating phase transitions
C) Circulating ambient air over the battery pack
D) Distributing heat evenly across the battery pack
Answer: C)
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Quiz
Question 4
How do Thermal Interface Materials (TIM) contribute to
battery thermal management?
A) Increase battery capacity
B) Improve heat transfer between battery cells and cooling
elements
C) Enhance energy efficiency
D) Absorb and release thermal energy during phase
transitions
Answer: B)
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Quiz
Question 5
What distinguishes active phase change cooling
from passive phase change cooling?
A) Initiating phase transitions
B) Absorption and release of thermal energy
C) Requirement of external power
D) Use of refrigeration cycle
Answer: C)
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Thank You!
