-40°C 12.8V 14.4Ah LiFePO4 Low Temperature Battery Pack
CMB specializes in LiFePO4 low-temperature battery pack solutions for outdoor equipment, offering a wide range of form factors and specifications for demanding applications. Our engineering team focuses on delivering reliable battery performance in extreme environments. From low-temperature cell selection and custom BMS design to advanced battery pack assembly, we develop application-specific solutions designed to perform when it matters most.
01 The Challenge
The customer required a custom battery pack for outdoor lighting and signal light applications operating in a rugged and harsh outdoor environment from -40°C to +60°C.
The battery needed to provide high capacity within a compact form factor while maintaining reliable charging and discharging performance across a wide temperature range.
02 Our Solution
To meet the extreme low-temperature requirements, CMB developed the pack in three steps.
CMB selected 3.2V 3.6Ah low-temperature LiFePO₄ cells specifically suited for the application.
Based on the required capacity and available space, the battery was designed in a 4S4P configuration using 26650 low-temperature LiFePO₄ cells.
CMB also developed a customized BMS using a specialized IC to improve the battery pack’s low-temperature charging and discharging performance.
By combining appropriate low-temperature cell selection, customized BMS design, and compact battery pack assembly, CMB developed a battery solution tailored to the customer’s application requirements.
12.8V 14.4Ah LiFePO4 Low Temperature Battery Pack Design
Product Highlights
- Configuration: 4S4P using 26650 low-temperature LiFePO₄ cells
- Nominal voltage: 12.8V
- Capacity: 14.4Ah
- Max. continuous charge/discharge current: 3A
- Operating temperature range: -40°C to +60°C discharge, -30°C to +60°C charge
- Cycle life target: 4,000 cycles @ 80% DOD
- Safety feature: Customized BMS with specialized IC optimized for low-temperature charge/discharge performance
Engineering Highlights
This project demonstrates CMB’s engineering approach to low-temperature battery pack development, from cell selection and BMS design to application-specific battery integration.
1
Low-Temperature Cell Selection
Selecting the right low-temperature cell is the foundation of a reliable battery solution.
CMB has established a database of low-temperature cells and continuously evaluates and tests different cell options for low-temperature applications. Based on the customer’s operating conditions and battery requirements, our engineering team evaluates the overall cell performance and selects the most suitable cell for the application.
This approach allows us to consider the overall performance of the cell rather than relying on a single specification, helping us develop a more reliable battery solution for demanding low-temperature environments.
2
Customized BMS Design
The BMS was customized with a specialized IC to support improved charging and discharging performance under low-temperature conditions.
The BMS design was developed according to the specific operating temperature range and performance requirements of the battery pack, with particular attention to the challenges associated with charging and discharging at different low-temperature conditions.
3
Compact Battery Pack Design
The 4S4P configuration allowed the required 14.4Ah capacity to be integrated into a compact 130×115×70 mm battery pack.
The battery structure and internal layout were designed around the available space and application requirements, allowing the battery to achieve the required capacity while maintaining a compact form factor.
4
Application-Specific Engineering
Rather than relying on a standard battery configuration, CMB developed the battery around the customer’s specific temperature, capacity, dimensional, and application requirements.
For low-temperature applications, we pay particular attention to potential bottlenecks and risk points that can affect battery charging and discharging performance at different low-temperature conditions. By identifying these critical points during the design process, we aim to improve battery reliability and reduce potential performance risks under demanding operating conditions.
| No. | Item | Parameter | Remark |
|---|---|---|---|
| 1 | Nominal Voltage | 12.8V | 3.2V/Cell |
| 2 | Nominal Capacity | 14.4Ah | @0.2C |
| 3 | Minimum Capacity | 14Ah | |
| 4 | Shipment Voltage | / | |
| 5 | Initial Internal Impedance | ≤25mΩ | AC 1KHZ |
| 6 | Standard Charge Voltage | 14.6V | 3.65V/Cell |
| 7 | Standard Charge Current | 2.9A | @0.2C |
| 8 | Max. Charge Current | 3A | |
| 9 | Standard Discharge Current | 2.88A | @0.2C |
| 10 | Max. Discharge Current | 3A | |
| 11 | Burst Discharge Curren | 6A | |
| 12 | Discharge Cut-off Voltage | 10V | 2.5V/Cell |
| 13 | Cycle Life | ≥4000cycles | Retention: ≥80% |
| 14 | Charge Temperature | −30°C~+60°C | Standard Charge |
| 15 | Discharge Temperature | −40°C ~ +60°C | Standard Discharge |
| 16 | Storage Temperature | -20°C~ +35°C | ≤3 Months |
| -20°C~ +25°C | ≤1 Year | ||
| 17 | Weight | About 1.3 | kg |
| 18 | Special Request |
Related Low Temperature LiFePO4 Battery Pack Cases
-40°C Low Temperature 12.8V 14.4Ah 4S4P LiFePO4 Battery Pack FAQs
Does -40°C mean the battery can be charged at that temperature, or only discharged?
Only discharged. This pack’s rated discharge range is -40°C to +60°C, but the charge range is narrower at -30°C to +60°C. In practice this means the light or signal fixture can turn on and draw power at -40°C, but any charging circuit (e.g., solar or mains trickle charging) should be designed to hold off charging below -30°C to protect the cells.
Why is the battery pack configured as 4S4P instead of a larger single-string cell?
The 3.2V 3.6Ah 26650 cell CMB selected for this application tops out at 3.6Ah per string. To reach the required 14.4Ah capacity inside a compact housing, four of these strings are wired in parallel (4P) rather than sourcing a single larger-capacity cell — which keeps the pack at 130×115×70mm while still clearing the “over 12Ah” requirement.
What testing or certification backs the transport and safety of this battery pack?
CMB battery packs are UN38.3 tested for lithium battery transport and manufactured under ISO 9001. Additional certification documentation (e.g., CE, UL) for this specific SKU is available upon request .
Can this 12.8V 14.4Ah configuration be adapted to a different voltage or capacity for another outdoor lighting project?
Yes. CMB builds this battery pack around the customer’s specific temperature range, capacity, and footprint requirements rather than offering it only as a fixed SKU — the same 26650 low-temperature cell and BMS approach can be reconfigured in different series/parallel arrangements to hit a different voltage or Ah target.
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