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Fortress Power | eFlex 5.4kWh LFP Battery

SKU eFlex 5.4

Authorized Dealer

Warranty Included

Original price $2,583.00 - Original price $2,583.00
Original price
$2,583.00 - $2,583.00
Current price $2,583.00

Item Status : Limited Stock

Leaves Manufacturer's Warehouse in 2-3 Business Days. ETA Delivery 5-7 days. Easy 30 Day Returns.

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  • High Quality U.S Made Products
  • No Sale Tax (Exclusions Apply)
  • Free & Fast Delivery
  • Manufacturer Warranty Included

Cinematic Corner

Fortress Power  eFlex 5.4kWh LFP Battery

Fortress Power eFlex is a versatile energy storage solution with a scalable capacity of 5.4 kWh. Built upon secure and energy-dense prismatic Lithium Iron Phosphate cells, this system ensures safety and reliability.

The eFlex incorporates a digital processor Battery Management System (BMS), featuring high-amperage contactor disconnects and advanced Closed-Loop inverter communication. It meticulously monitors individual cell voltages, temperatures, and balances cells to optimize performance and extend lifespan.

With Canbus, Modbus, and Wi-Fi communication capabilities, this system is IoT-ready, offering seamless integration with smart networks. Its IP65-rated casing provides robust protection against water spray and dust ingress from any direction.

For added convenience, the eFlex offers flexible mounting options including wall, floor, and server rack installation, catering to various applications such as renewable energy, marine, RV, mobile, telecom, and railway.

Key Features

  • Durable and Reliable for Daily Use
  • Utilizes Safe Lithium Iron Phosphate Technology (LiFePO4)
  • Achieves 98% Round Trip Efficiency
  • Offers Flexible Mounting Options
  • Allows Remote Monitoring via Wi-Fi, Modbus, and Canbus
  • BMS Ensures Monitoring and Balancing of Individual Cells
  • NRTL Certified to UL9540 and UL9540a Standards

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
Dimensions (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%



Manuals & Downloads


eFlex Data Sheet
eFlex SPANISH Data Sheet
eFlex SPANISH Brochure

Installation Guides 

eFlex Owner / Installation Manual
Inverter Guides


UL9540 / UL1973 Certificate
UL9540a Large Scale Fire Test Report

Racking Details

DuraRack Manual
Flexrack Technical Notes
Customer Server Rack Guide

Words From Our Happy Customers

Meet Our Experts

Meet Our Experts

Need help choosing the right products for your needs? Our team of highly trained experts has the knowledge and passion to help. Just pick up the phone and give us a ring. Or let's converse via live chat. We love assisting and lending a hand (or an ear).

Other shoppers asked

Does energy storage work well with my solar system?

Yes. On the grid? Absolutely! Energy storage adds a lot of value to your solar systems. It keeps your solar system operating when your utility service is interrupted. Without energy storage, your PV system will be forced to shutdown when the grid is off. If you live off grid, energy storage enables you to use the clean solar energy to power your home day and night.Fortress Power also knows you’re a fan of conservation—energy storage saves both your surplus solar energy and your cash since it reduces on grid energy dependence.

Can I use energy storage without solar panels?

Absolutely. For on grid clients, a home energy storage unit  stores energy from your electricity provider. If an outage occurs, home energy storage can provide up to 24 hours of potentially life-saving power. Need more reassurance? Fortress Power offers batteries with larger storage capabilities, completely customizable to your needs. And, like you, we appreciate saving money. When electricity is at its lowest daily rate, our smart energy storage units use that period to charge. When peak electric use occurs, our energy storage units can discharge power to suit your lifestyle.

What about power outage protection?

Power interruptions shouldn’t disrupt your schedule. An energy storage system will keep your solar system operating during grid outages. When paired with solar panels, an energy storage system supplies unlimited energy delivery. The solar panels power your home during the day and use any excess power to charge the battery. At night, the system keeps your space bright. When used without solar panels, power outage support is dependent on battery size and your energy use. Batteries providing at least 12 hours of backup power are safest.

Are home energy storage systems financially beneficial?

You can use the energy storage to shelve your peak usage. When electricity is at its lowest daily rate, our smart energy storage uses that period to charge. During the peak periods, our energy storage system can power your home, reducing your electricity bill. Clients with solar panel installations enjoy a faster return on investment.

What is Lithium batteries lifespan?

We provide a 10 year product warranty and guarantee up-to 8000 cycles, whichever comes first. Speak to our representatives for details.

Why choose Lithium Iron Phosphate over Lithium Ion batteries?

We use Lithium Iron Phosphate (LiFePo4; Lithium Ferro Phosphate) technology – the safest lithium technology in the industry. It’s environmentally friendly and can be fully recycled. While Many other competitors, such as LG Chem, Tesla and Panasonic use cobalt-based Lithium-Ion battery, which has a very poor thermal stability. Any short circuit or cell-breakage can cause thermal runaway and catch fire. And comparatively, Lithium Iron Phosphate battery deliver substantially higher amount of life cycles. We guarantee up-to 6000 cycles, while LG Chem, Tesla and Panasonic provide less than 3000 cycles.

Are Fortress Lithium batteries widely compatible?

Yes, our batteries are designed to work with all 48V chargers and hybrid inverters. We work well with Schneider, Outback, Magnum, Sol-Ark, Victron, Morningstar and so on. Please Check out our Inverter Compatibility list.

Are permits required for installation?

Legal requirements vary by location. Fortress Power’s technical support team will help you on obtaining permits.

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Direct to your door 2-7 business days or less

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Nothing is more important to us than the quality of our products. Each of the manufacturers we work with have been vetted for quality, and we have personally visited manufacturing facilities to ensure high-quality production practices.

We Operate in the USA

Golden Age Hub services the 48 contiguous united states with high-quality luxury products. Our staff is entirely US-Based and our equipment ships directly out of warehouses on US soil.

Easy Refunds & Returns

If your equipment isn’t what you expected, we make refunds and returns quick and easy. Just email and we’ll take care of you from there.

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