Fortress eFlex 5.4 kWh Lithium Ferro Phosphate LFP Battery

Fortress eFlex 5.4 kWh Lithium Ferro Phosphate LFP Battery

Regular price $2,615
Regular price -% Sale price $2,615
50 IN STOCK
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Fortress eFlex 5.4 kWh Lithium Ferro Phosphate LFP Battery

Fortress eFlex 5.4 kWh Lithium Ferro Phosphate LFP Battery

Fortress Power
MPN No: eFLEX 5.4
In Stock
Regular price $2,615
Regular price -% Sale price $2,615

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Expected ship date May 14 - 17 About shipping

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Regular price $2,615
Regular price -% Sale price $2,615

Specifications

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Documents
.PDF
Documents
Data Sheet
Installation Guide
Warranty Guide

Fortress eFlex 5.4 kWh Lithium Ferro Phosphate LFP Battery

Key Benefits

  • Provides 5.4kWh of high-efficiency energy storage with >98% round-trip efficiency

  • Compact, wall-mountable, or rack-mountable design for flexible installation

  • Long cycle life with 8,000 cycles at 80% depth of discharge

  • Built-in BMS ensures battery protection and performance in real time

  • IP65-rated enclosure for outdoor or indoor use in harsh weather conditions

Special Technology

  • Tier 1 automotive-grade prismatic LiFePO4 cells for maximum reliability

  • Advanced digital BMS with contactor disconnects and individual cell balancing

  • Supports Canbus, Modbus, and Wi-Fi communication protocols for inverter integration

  • Compatible with major inverter brands including Sol-Ark, SMA, Schneider, Victron, Growatt, and more

  • Patented aluminum enclosure with 4x improved thermal performance compared to competitors

Warranty

Fortress Power offers a 10-year warranty on the eFlex 5.4 lithium battery, with an expected cycle life of 8,000 cycles at 80% DoD, ensuring long-term value and peace of mind.

Best Use

  • Ideal for residential backup and whole-home energy storage

  • Perfect for off-grid cabins, zero-export systems, and demand response programs

  • Suitable for grid-tied PV systems with AC or DC coupling

  • Designed for environments requiring NEMA 3R/IP65 outdoor-rated enclosures

Specifications Table

Attribute Specification
Product Name Fortress Power eFlex 5.4
Usable Capacity 5.374 kWh
Nominal Voltage 51.2V
Nominal Capacity 105Ah
Round-Trip Efficiency >98%
Depth of Discharge Up to 100%
Cycle Life 8,000 cycles at 80% DoD
Continuous Discharge 60A (3kW DC)
Peak Discharge (60 min) 100A (5kW)
Surge Discharge (5 sec) 130A (6.6kW)
Charge Voltage 54.4V
Charge Current (Recommended) <55A (Max 100A)
Enclosure Rating IP65 / NEMA 3R
Dimensions (L × W × H) 21.5 × 17.5 × 7.2 inches
Weight 108 lbs
Certifications UL9540, UL1973, UL1642, UL9540A, UN38.3
Operating Temp Range -4°F to 131°F (Discharge)
Mounting Options Wall Mount, Floor Stand, 19” Rack
Warranty 10 Years

About Fortress Power

Fortress Power is a U.S.-based energy storage manufacturer committed to delivering advanced lithium battery systems for homes, businesses, and utilities. With a focus on safety, reliability, and innovation, Fortress Power’s products are engineered for superior thermal management, ease of installation, and compatibility with leading inverters. Their batteries meet UL9540 and UL1973 standards and are designed to perform in diverse climates and use cases. Fortress Power empowers customers to achieve energy independence with clean, efficient, and intelligent battery solutions.

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Need Assistance?
We’re here to help! If you have any questions or need more information before making your purchase, don’t hesitate to call us at 1-800-230-7004. Our knowledgeable and friendly team is ready to assist you with product details, installation advice, or the purchasing process.

Why Buy From Us?
Trusted Supplier: We work with Tier 1 manufacturers who stand behind their products.

Expert Support: Our team is here to guide you every step of the way.

Manufacturer-Backed Warranties: Fortress Power offers a 10-year warranty on the eFlex 5.4 lithium battery, with an expected cycle life of 8,000 cycles at 80% DoD, ensuring long-term value and peace of mind.

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