Fortress Power eFlex MAX 5.4kWh Lithium Battery Storage | 8,000+ Cycles | 99% Efficiency | Outdoor-Ready Design

Fortress Power eFlex MAX 5.4kWh Lithium Battery Storage | 8,000+ Cycles | 99% Efficiency | Outdoor-Ready Design

Reliable Backup. Long-Term Value. Ultimate Flexibility.

Whether you're building a resilient home energy system, powering off-grid living, or seeking sustainable storage for solar energy, the Fortress Power eFlex MAX delivers industry-leading performance and durability. With 5.4kWh of usable energy, 8,000+ cycle life, and 99% round-trip efficiency, this high-performance 48V lithium iron phosphate (LFP) battery is built to deliver uninterrupted power—anywhere, anytime.

From harsh outdoor environments to tight indoor spaces, the eFlex MAX is designed for reliability, easy integration, and long-lasting savings—without the complexity of traditional storage systems.

Key Features:

• Maximum Lifespan + Performance: Engineered for 8,000+ charge cycles and a 10+ year lifespan, the eFlex MAX delivers consistent, high-efficiency power with minimal degradation. Its patented aluminum shell ensures exceptional thermal stability and durability, even in extreme conditions.
• Rugged, Weatherproof Construction: With a saltwater-resistant, IP65-rated aluminum enclosure, the eFlex MAX is built for indoor or outdoor installation—no extra protective housing required. It's perfect for basements, garages, backyards, or even boats and RVs.
• Ultra-Efficient Operation: Achieve up to 99% round-trip efficiency with just 2W of standby consumption. Ideal for solar self-consumption, off-grid cabins, and energy-conscious homeowners looking to maximize every kilowatt-hour.
• Effortless Scalability: Need more storage? No problem. Integrated busbars allow you to connect multiple units in parallel, simplifying installation and supporting higher current loads for larger energy systems.
• Flexible, Code-Compliant Installation: Mount it on the wall or floor—your choice. The waterproof front cover and streamlined design allow for quick, clean, and compliant installations with minimal wiring or conduit required.
• Smarter System Integration: The eFlex MAX is designed for seamless compatibility with popular hybrid inverters and energy management systems, enabling intelligent monitoring, load shifting, and time-of-use optimization.

Applications:

• Residential energy storage
  
• Apartments and condos
  
• Off-grid cabins and homesteads
  
• RVs, boats, and marine systems
  
• Solar backup systems
  

What's Included:

• 1 × Fortress Power eFlex MAX 5.4kWh Battery
  
• 1 × Mounting Bracket Kit
  
• 1 × User Manual
  
• 1 × Warranty Registration Card
  

Note: The eFlex MAX 5.4kWh is not compatible with the standard eFlex 5.4kWh model.

Specifications

Shopping Guide

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