Explore rechargeable 21700 lithium-ion battery cells for high-capacity, high-drain and custom battery pack applications. Compare 21700 cells by capacity, discharge current, voltage and manufacturer specifications to select the right cell for your project.
A 21700 battery is a cylindrical lithium-ion cell with a nominal
diameter of approximately 21 mm and a length of approximately
70 mm. The format is used in battery packs and equipment where
energy capacity, discharge performance and efficient cylindrical
cell packaging are important.
Many rechargeable 21700 lithium-ion cells operate at a nominal
voltage around 3.6V to 3.7V, although exact voltage limits,
capacity, maximum current, weight and dimensions depend on the
specific manufacturer and cell model.
Choosing the correct 21700 cell requires more than comparing
capacity. Current capability, cycle requirements, operating
temperature, cell chemistry, dimensions and the intended battery
pack configuration should also be considered.
01
Larger Cylindrical Format
The 21700 format is physically larger than an 18650 cell and
can provide additional capacity or performance depending on
the specific cell design.
02
High-Capacity Options
21700 cells are available in configurations designed for
applications where increased energy per cell is important.
03
High-Drain Options
Some 21700 models are engineered for higher continuous
discharge current and power-oriented battery pack applications.
04
Battery Pack Integration
Series and parallel arrangements allow 21700 cells to be
configured around application voltage, capacity and current
requirements.
Cell format comparison
21700 vs. 18650 Batteries
Both 21700 and 18650 batteries are widely used cylindrical
lithium-ion formats. The right format depends on the electrical,
mechanical and thermal requirements of the final product or
battery pack.
Design factor
21700
18650
Approximate format
21 × 70 mm class
18 × 65 mm class
Physical size
Larger cylindrical format
Smaller cylindrical format
Capacity per cell
Often available with higher capacity per cell
Wide range of capacity options
Pack design
May reduce cell count for some energy requirements
Allows compact and highly flexible pack layouts
Selection
Choose by capacity, current, dimensions and application
Choose by capacity, current, dimensions and application
The best 21700 battery for a project depends on how the cell
will be used. Capacity is important for runtime, while discharge
current is important for power demand. Weight, dimensions,
temperature limits, cycle life and availability can also affect
the final choice.
Capacity
Compare amp-hour or milliamp-hour capacity according to the
runtime and energy required.
Continuous discharge current
The selected cell should support the continuous current required
by the application.
Peak current
Short-duration load requirements should stay within the
documented limits of the cell and pack.
Nominal voltage
Verify cell voltage and charge limits before determining
battery pack series count.
Energy density
Energy per unit mass or volume can influence compact and
weight-sensitive designs.
Cycle requirements
Expected service life and operating conditions can influence
cell selection.
Temperature
Charge, discharge and storage temperatures should remain
within manufacturer specifications.
Availability
Cell supply and consistency matter when designing products
intended for repeat production.
Capacity and power
High-Capacity and High-Drain 21700 Batteries
21700 cells are designed for different performance priorities.
Some emphasize maximum capacity and runtime, while others are
optimized for higher discharge current and power.
Capacity and discharge current should be evaluated together.
A battery with the highest capacity is not automatically the
correct cell for a high-power application, and a high-current
cell may not provide the longest runtime.
Energy-focused
High-Capacity 21700 Cells
Designed for applications where stored energy and runtime
are major priorities.
Power-focused
High-Drain 21700 Cells
Designed for applications with greater continuous or peak
current requirements.
Balanced performance
Energy and Current Balance
Some cells provide a compromise between capacity and discharge
capability for general battery pack use.
Popular 21700 battery models
Compare 21700 Lithium-Ion Cells
Cell specifications vary by manufacturer and model. Review the
product page and technical data for the exact battery before
selecting it for a battery pack or equipment design.
21700 cells can be connected in series and parallel to create
lithium-ion battery packs with different voltage, capacity and
current characteristics.
Series groups primarily determine pack voltage. Parallel cells
increase amp-hour capacity and can increase available current
when the selected cells, interconnects and battery management
system are designed appropriately.
Series configuration
Determines the nominal operating voltage of the pack.
Parallel configuration
Increases pack capacity and influences current capability.
Battery management system
Protection should match chemistry, series count and current.
Thermal and mechanical design
Cell spacing, interconnects, cooling and enclosure design
affect the finished battery pack.
Applications
Applications for 21700 Lithium-Ion Cells
21700 batteries can be used in products and battery systems
requiring different combinations of energy capacity, current
capability, physical size and cycle performance.
Battery packs
Industrial equipment
Robotics
Portable equipment
Electric mobility
Power systems
OEM products
Custom lithium-ion systems
Battery pack design
Building a Battery Pack with 21700 Cells?
Configure an initial series and parallel arrangement with the
Voltaplex Battery Pack Builder, or provide your voltage,
capacity, current, dimensions, application and production
requirements for review.
The 21700 designation refers to the approximate cylindrical
cell format: about 21 mm in diameter and 70 mm in length.
Exact dimensions can vary slightly by cell model and manufacturer.
What voltage is a 21700 lithium-ion battery?
Many rechargeable 21700 lithium-ion cells have a nominal
voltage around 3.6V to 3.7V. Exact nominal voltage, maximum
charge voltage and discharge limits should be confirmed using
the datasheet for the specific battery.
Is a 21700 battery larger than an 18650?
Yes. A 21700 cell is approximately 21 mm in diameter and
70 mm long, while an 18650 cell is approximately 18 mm in
diameter and 65 mm long.
Are 21700 batteries higher capacity than 18650 batteries?
The larger 21700 format allows manufacturers to offer cells
with different capacity and power characteristics. Capacity
should be compared using the specifications of the exact
models rather than cell format alone.
What is a high-drain 21700 battery?
A high-drain 21700 battery is designed to support relatively
high discharge current. The exact continuous and peak current
limits vary by model and should be taken from manufacturer
specifications.
Can 21700 cells be used in custom battery packs?
Yes. 21700 cells can be connected in series and parallel
configurations when the battery system is engineered for the
required voltage, capacity, current, BMS, interconnects,
thermal performance and enclosure.
How do I choose between a high-capacity and high-current 21700 cell?
Start with the application's required runtime and current.
Higher-capacity cells may be appropriate when energy is the
priority, while higher-discharge cells may be more suitable
for applications requiring greater power. The complete
electrical and mechanical design should be considered.
Do 21700 battery packs need a BMS?
Rechargeable lithium-ion battery packs commonly require
battery management or protection electronics matched to the
chemistry, series configuration, current requirements and
intended application.
BUILT FOR YOUR NEEDS
Custom battery packs provide a level of precision and compatibility unmatched by off-the-shelf options. Whether you need a unique configuration for medical devices, industrial machinery, or consumer electronics, we deliver. Our team of experienced battery engineers will work closely with you to design and manufacture batteries that meet your specific voltage, capacity, and size requirements.
Reliable and Efficient Performance
Our custom battery packs maximize energy output, reduce downtime, and enhance the overall performance of your devices. Each pack is engineered with precision to meet specific voltage, capacity, and size requirements, ensuring optimal performance for every application.
Flexible 18650 Battery Pack Design
One of the most versatile solutions we provide is the 18650 battery pack. Known for high energy density and durability, 18650 cells are ideal for industrial equipment, consumer electronics, and renewable energy systems. Our expertise ensures your custom battery pack exceeds expectations, even for the most complex projects.
Prioritizing Safety in Every Design
Safety is a top priority in every battery we manufacture. Each custom pack includes advanced safety features, such as:
Overcharge protection
Thermal management
Short-circuit prevention
Over-discharge and over-current safeguards
All packs undergo rigorous testing and comply with UL, CE, and CQC certifications, guaranteeing reliability and safety for your applications worldwide.
Industries We Serve
Custom battery packs serve many industries, addressing diverse energy needs with precision and reliability.
Medical Devices
Our custom battery packs are designed to power life-saving devices like portable ventilators, defibrillators, and diagnostic tools.
Consumer Electronics
Whether you’re developing wearable devices, smart home technology, or portable gadgets, our custom configurations deliver superior power and reliability.
Renewable Energy Systems
From solar energy storage to wind turbine power systems, our solutions provide the reliability and efficiency needed to optimize energy harnessing and usage.
Electric Vehicles (EVs)
Voltaplex specializes in creating custom lithium battery packs tailored to the needs of EVs, ensuring exceptional performance and extended range.
Request Your Custom Battery Pack
Voltaplex Energy is ready to design and manufacture battery packs tailored to your specifications. Whether you need a standard 18650 configuration or a fully customized lithium-ion solution, our team will create a reliable, high-performance battery pack designed to power your products safely and efficiently.
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