Fortress Power eFLEX 5.4 kWh Lithium Iron Phosphate Battery

Fortress eFLEX 5.4

Note: We no longer have stock on this battery, Please look at the new verions of this battery, Fortress eFLEX 5.4 Kit.

In stock

Fortress Power eFLEX 5.4 kWh LiFePO4 Battery

This battery can only ship via freight truck. If you have any questions about shipping methods, please email us or call us at 800 383-0195.

Fortress Power announces the eFlex 5.4 kWh scalable energy storage battery solution. The unit uses safe and high energy density prismatic Lithium-Iron-Phosphate cells. The battery has a built-in data storage and Wi-Fi for remote monitoring and troubleshooting ability. The smart relay-based Battery Management System (BMS), supports closed-loop communication with various 48V hybrid inverters on the market. Additionally, the BMS monitors and balances the voltage and temperature of each individual cell to maximize reliability and longevity. It has the highest round trip efficiency in the industry at 98%. This unit has wall mounting functionality and fits well into standard server racks for large systems.

High Durability and long-lasting: 10 Year Warranty with the safe and premium prismatic Lithium-Iron-Phosphate cells

Versatile Applications: Expandable from 5.4 kWh to 81 kWh for residential, commercial, railway, military and telecommunications applications

Lowest Cost Per Cycle: High energy throughout with exceptional life span (6000+ cycles) and hight round-trip efficiency (>99%)

Monitor from Anywhere: The battery has a built-in data storage Wi-Fi for remote monitoring and troubleshooting ability

Waterproof and saltwater resistant: The sleek-looking aluminum cabinet has IP65 waterproof rating to prevent salt-water corrosion


  • Total Energy: 5.376 kWh
  • Nominal Voltage: 51.2(48)V
  • Voltage Range: 45-58.4 V
  • Max. Charge Current(Continuous): 100 Amp / Recommended Charge Current: 55A
  • Max. Discharge Current(Continuous): 100 Amp / Recommended Continuous Discharge Rate: <68A
  • Recommend Storage temperature: 32 to 95 F
  • Charge temperature: 32 to 113 F
  • Capacity: 105 Amp-hour
  • Dimension(H x W x D): 7.2" x 17.5" x 21.5"
  • Weight: 116 lbs

The following sizing recommendations will affect the warranty if not followed. Fortress Power minimum battery bank sizing recommendations for common battery-based inverters (Magnum, OutBack, Phocos, Schneider Electric, SMA Sunny Island, Sol-Ark, Victron, etc): Fortress sizing recommendations.

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SKUFortress eFLEX 5.4
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