eFlex 5.4kWh LFP Battery

eFlex 5.4 kWh | Compact, Flexible Energy Storage

A wall-mounted or rack-mountable 48V LFP battery designed for partial home backup, solar self-consumption, and scalable energy storage.

eFlex 5.4 kWh LFP Battery

Rugged, Long-lasting, Daily Use Battery

The Fortress Power eFlex is a 5.4 kWh scalable energy storage solution based on safe and energy dense prismatic Lithium Iron Phosphate cells. The digital processor Battery Management System (BMS) includes high amperage contactor disconnects and advanced Closed-Loop inverter communication, as well as individual cell voltage monitoring, temperature monitoring, and cell balancing to maximize reliability and longevity.

Canbus, modbus, and wifi communication enable internet-of-things compatibility. The IP65 case ensures direct water spray and dust will not penetrate the battery internals from all directions. The unit can be wall mounted, floor mounted, and server rack mounted for hard-to-reach access in renewable, marine, RV, mobile, telecom, railway applications and more.

*The eFlex MAX 5.4kWh and the eFlex 5.4kWh LFP Battery are NOT compatible with each other.

Applications

Residential

FEATURES

Reliable Performance for Daily Cycling

Designed for everyday use, the eFlex delivers consistent, long-lasting energy storage — ideal for solar self-consumption, partial home backup, and energy cost savings.
Safe, Proven LFP Chemistry

Built with advanced lithium iron phosphate (LiFePO₄) technology, the eFlex provides thermal stability, non-toxic materials, and industry-leading safety performance.
High Round-Trip Efficiency

With up to 98% round-trip efficiency, the eFlex maximizes the value of every kilowatt-hour stored — reducing energy loss and improving system ROI.

Versatile Mounting Options

Install vertically or horizontally, wall-mounted or in a rack — the eFlex offers flexible configurations to fit small spaces and custom system designs.
Smart Monitoring & Communication

Stay in control with built-in Wi-Fi, CANBus, and Modbus connectivity. Monitor system performance in real-time and integrate seamlessly with leading inverters.
Certified for Safety & Compliance

The eFlex is NRTL-certified to UL9540 and UL9540A standards, ensuring it meets strict safety and fire prevention requirements for residential energy storage.

PRODUCT INFORMATION

Specifications
Downloads

General
Name	eFlex 5.4
Total Energy(kWh)	5.4
Max. Charge Current (Continuous) [A]	100
Max. Discharge Current (Continuous) [A]	60
Max. Pulse Current (for 5 sec) [A]	130
Capacity [Ah]	105
Voltage Range [V]	48-55
Charging Temperature [F]	32 to 113
Discharging Temperature [F]	32 to 140
Storage Temperature [F]	32 to 95
Dimension [L x W x H, inch]	21.5 x 17.5 x 7.2
Weight [lbs]	116
Life Cycles	8000 @ 80% DoD
Round Trip Efficiency	>98%

eFlex 5.4 kWh | Compact, Flexible Energy Storage