The document discusses key considerations for designing lithium-ion batteries for portable devices. It emphasizes that specifications are important to outline physical, environmental, and performance requirements upfront to guide development. Physical constraints, operating ranges, safety systems, and smart battery capabilities that provide information to devices affect costs. A good specification treats the battery design like a blueprint and ensures all necessary factors are addressed to reduce risks.
Design Considerations for Lithium Batteries Used in Portable Devices
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Design Considerations for Lithium
Batteries Used in Portable Devices
09.26.2019
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Agenda
What goes into a specification that can be easily turned into a product.
Understanding how the physical and environmental requirements
affect the design.
Cover the major cost drivers of a final battery to power a device.
Safety Systems used to protect the battery pack during operation and
charging.
Smart Batteries – what are they and what does this really mean?
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Importance of a Specification
A specification is necessary. It
would be like building a house
without building plans.
– Project failure and cost overruns
happen without it
Upfront requirements and
performance specs are outlined
early at the start of each project.
– It is an investment with great
return.
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Importance of a Specification
A specification provides a full
understanding of the requirements
upfront before development begins.
– Provides clear and concise direction
– Opens dialog with the customer on options
available
– Reduces wasted time and cost in changes
– No surprises at the end of the project.
Helps with product integration,
interface, and handshaking
requirements.
– It goes beyond just the battery.
– Seamless integration
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Importance of a Specification
Physical and electrical interface and environmental aspects must be
defined.
– Needed for proper cell selection
– Additional electronics defined, if required.
– Electrical and physical protection.
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Physical and Environmental
There are many factors of how the physical and environmental
requirements affect the design.
– How big or small is the battery?
– Is it required to deliver power or energy or both?
– Is it even possible to design a battery solution to meet the requirements?
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Physical and Environmental
What are the high and low operating ranges?
– Do these exceed today’s battery technologies?
– What can be done if they do?
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Cost Drivers
Basic cells that go into a battery are normally inexpensive, so what
makes some batteries more expensive than others?
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Cost Drivers
Chemistry and number of cells.
– What protections are required?
– Quality of the cells:
• Tier 1 cells
• Tier 2 cells
– The power and energy rating
of the cells.
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Cost Drivers
Physical geometry of the cells and how they sit within the battery.
– Plastic enclosure or heat shrink?
– What are the drop requirements?
– Does the design need IP67 rating?
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Cost Drivers
Does the battery have electronics enclosed within?
– Fuel gauging
– Integrated charger within the battery
– Customer electronics in the battery
– High-power / high-current
connector needed
– Built-in inrush protection
– Built-in fan
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Safety and Protection
All chemistries require protection
to some degree.
All chemistries can overheat
when shorted,
– Overcurrent protection is
required.
All chemistries can overheat
when overcharged.
– Over temperature and/or
overvoltage protection is
needed.
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Safety and Protection
Li-Ion based chemistries require more protection than others.
– Protection from overheating
• Heat prevention
• Heat dissipation
– Protection from reduced cycle life
• Undervoltage protection
– Protection charging and discharging outside of
allowable parameters
• Voltage / Current / Temperature
– Secondary protection
• Medical and IT
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Smart Batteries
A Smart Battery Pack is a battery capable of providing information
about its operating parameters to the outside world.
– These parameters can include:
• Charge level
• Battery voltage
• Cell voltage
• Charge and discharge currents
• Battery temperature
• State of health
• Remaining run time
• Remaining charge time
• And many more
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Smart Batteries
The most common method of conveying the information to the host
system is through:
– I2C
– SMBus
– Single wire communication
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Smart Batteries
A smart battery can also be a battery with additional circuitry added
that it controls:
– Built-in charger with various topologies
– Customer electronics
– Built-in fan
– Integrated Heater
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Summary
Treat your specification like a blueprint.
Know your physical and environmental requirements.
Understand what the major cost drivers are.
Know what safety systems need to be in place.
What operating parameters need to be provided to the outside world.
Additional built-in electronics increase cost.
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Q&A
Questions?
– Enter any questions you may have
in the control panel
– If we don’t have time to get to it, we
will reply via email
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Thank You
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For more information email sales@epectec.com.
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