Cylindrical 26650 Cell
BAK 26650FS4
Cylindrical 26650 cell delivering 4 Ah capacity with 138 Wh/kg energy density and 12 A maximum discharge rate.
Overview
The BAK 26650FS4 is a lithium-ion Li-ion cylindrical 26650 cell designed for applications that demand reliable performance. Manufactured in china, this cylindrical 26650 cell delivers 4 Ah capacity and 12.6 Wh of energy at a nominal voltage of 3.2 V, with a maximum continuous discharge capability of 12 A, making it suitable for general-purpose applications with moderate power requirements.
Key Features
Discharge rate: 12 A continuous (3.0 C)
Charging rate: 1.5 C charging rate
Energy density: 138 Wh/kg
Power density: 422 W/kg
Applications: power tools, e-mobility, energy storage
Technical Specifications from the Manufacturer
Parameter
Manufacturer
BAK
Model
26650FS4
Type
Li-ion
Form factor
Cylindrical 26650
Country of origin
China
Release year
2019
Nominal voltage
3.2
Energy capacity [Wh]
12.6
Capacity [Ah]
4
Gravimetric energy density [Wh/kg]
138
Gravimetric power density [W/kg]
422
Max continuous discharge [A]
12
Volume [cm³]
36.13
Mass [g]
91
Positive electrode (cathode)
LFP
Negative electrode (anode)
Graphite
Value
Applications & Use‑Cases
The BAK 26650FS4 is well suited to the following applications due to its cylindrical 26650 and balanced performance.
Power Tools: Needs sustained high discharge for continuous operation under load, low voltage polarisation to maintain tool performance, and mechanical robustness for demanding work environments.
E-Mobility: Requires balanced energy and power density for range and acceleration, high cycle life for daily use, and robust calendar life to ensure long-term reliability.
Energy Storage: Requires long cycle life for daily charge-discharge operation, stable capacity retention over years of service, and safe operation in grid-connected or islanded applications.
General Applications: Suitable for applications requiring reliable lithium-ion performance with proven cycle life, consistent capacity delivery, and operational safety across diverse use cases.
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Performance & Model Data
Below are modelled performance metrics for the BAK 26650FS4 across key indicators, including constant current behaviour, rate capability, temperature dependence, and available power under representative drive cycle conditions.
Constant Current Voltage
Access BAK 26650FS4 constant-current discharge curves in Voltt to size your pack against the voltage window your system actually needs. (Chart shown is illustrative, not 26650FS4 data.)
Constant Current Temperature
Access BAK 26650FS4 thermal discharge data in Voltt to specify cooling and cell spacing before you commit to a pack layout. (Chart shown is illustrative, not 26650FS4 data.)
Pulse Power Behaviour
Access BAK 26650FS4 pulse power maps in Voltt to set peak current limits and parallel count for your worst-case load. (Chart shown is illustrative, not 26650FS4 data.)
Dynamic Profile Response
Access BAK 26650FS4 mission profile simulations in Voltt to prove the pack holds up over a real duty cycle before you build it. (Chart shown is illustrative, not 26650FS4 data.)
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Case Studies
See how we helped McMurtry reduce cell evaluation time by 70% through data driven testing and modelling.
Motorsports
McMurtry Automotive: Faster cell evaluation
McMurtry Automotive used The Voltt and validated cell models to evaluate the transition from the Molicel P45B to P50B during early pack concept development.
Side by side modelling enabled rapid comparison of electrical and thermal behaviour, avoiding lengthy physical test campaigns. This approach reduced cell evaluation time by seven months, allowing the team to lock in cell selection and pack assumptions earlier while lowering technical risk and accelerating vehicle development.
Comparison with Related Cells
Compare the BAK 26650FS4 with other cells offering comparable capacity and performance characteristics.
Model
Capacity
Max Discharge
Typical Use
Access Cell Data
Manufacturer Background
BAK
BAK Battery is a Chinese lithium-ion cell manufacturer producing cylindrical and prismatic formats
BAK Battery was founded in 2001 and is headquartered in Shenzhen, with its principal cell plants in Zhengzhou and Fuzhou. The company produces cylindrical 18650 and 21700 cells alongside prismatic and polymer formats, using both nickel-based and lithium iron phosphate chemistries. Its cells supply electric vehicles, light electric mobility, power tools, consumer electronics and backup energy storage, giving it volume across several high-turnover segments. BAK is vertically integrated across materials, cell production and pack assembly, and also operates a battery recycling business. Its relevance rests on long-running mass production in the established cylindrical formats and a cost position built on scale rather than novel chemistry.
Frequently Asked Questions
What is the capacity and voltage of the BAK 26650FS4?
The BAK 26650FS4 has a nominal capacity of 4.0 Ah and a nominal voltage of 3.2 V, providing 12.6 Wh of energy per cell.
What is the maximum continuous discharge capability of the BAK 26650FS4?
The BAK 26650FS4 supports continuous discharge rates up to 12 A, delivering exceptional power density of 422 W/kg.
How much does the BAK 26650FS4 weigh and what is its volume?
The cell has a mass of 91 g and a volume of 36.13 cm³.
In which industries is the BAK 26650FS4 commonly used?
The BAK 26650FS4 is used across e-mobility, energy storage, and general-purpose applications, applications that demand reliable performance and balanced specifications.
What is The Voltt and how does it accelerate cell evaluation?
The Voltt holds 500+ verified commercial cell datasheets alongside validated simulation models built from cells characterised in About:Energy's own lab. Engineers screen candidates against their real duty cycle before buying hardware, which cut cell evaluation time by seven months for McMurtry Automotive and reduces evaluation cycles by up to 70%.
What data can be extracted using The Voltt?
Constant-current discharge curves at multiple C-rates, DC internal resistance against state of charge and temperature, pulse power maps, thermal response, and full mission-profile simulation with user-defined pack configurations. Models are available as equivalent circuit, thermal, physics-based and degradation formats, exportable for use in MATLAB, Simulink and Python workflows.
