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Fortress Power LFP battery 105 AH 5.4kWh total capacity max. 10 year warranty A14 Wall mount bracket included - eFlex 5.4 kWh

Fortress Power LFP battery 105 AH 5.4kWh total capacity max. 10 year warranty A14 Wall mount bracket included - eFlex 5.4 kWh

$3,461.25 USD
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  • SKU:PES-ESS-BTS-0245
  • Documents:

    Datasheet

    Installation Guide

    Warranty
  • Height: 7.2
  • Isfollow: true
  • Isindex: true
  • Length: 17.5
  • Mpn number: eFlex 5.4 kWh
  • MPN Number: eFlex 5.4 kWh
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In Stock

Get yours today!

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9+ sold

In the last 7 days

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Flat Rate Shipping - Calculated at Checkout

Get it between Mon, Sep 22 - Wed, Sep 24

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Free Returns

Free Returns within 30 Days of Purchase

Lifetime Customer Support

Unlimited lifetime support, always available.

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Fortress eFlex 5.4 kWh battery — 48 V LiFePO₄ module (IP65)

The Fortress eFlex 5.4 kWh battery is a modern lithium iron phosphate (LFP) energy storage solution designed for homeowners and small commercial users who demand safety, performance, and long-term reliability. Built with advanced battery technology, this system delivers consistent power backup, seamless solar integration, and flexible installation options to meet today’s growing energy needs.

As energy independence becomes more important, the Fortress eFlex system stands out with its durable construction, intelligent battery management system (BMS), and scalable design. Whether used for backup power or daily energy optimization, this battery is engineered to perform efficiently for years.

Fortress eFlex 5.4 kWh battery is a compact, safe LFP pack (48 V, 105 Ah) with Wi-Fi/RS485/CAN comms and an IP65 outdoor enclosure—for fast installation with wall, rack, or floor mounting.

Key features

Fortress eFlex 5.4 kWh battery works with closed-loop 48 V inverters; BMS provides cell-level monitoring, 8,000-cycle life, and >98% RTE.

  • 5.4 kWh energy · 48–55 V operating · 105 Ah capacity
  • Max charge 100 A · max discharge 60 A · 130 A (5 s) pulse
  • IP65 enclosure; wall/rack/floor mounting options
  • Comms: RS485, CAN, Wi-Fi (OTA updates)
  • Round-trip efficiency >98%; life: ~8,000 cycles @ 80% DoD

Specifications

Fortress eFlex 5.4 kWh battery — specification box
Total energy 5.4 kWh
Nominal / operating V 48 V / 48–55 V
Capacity 105 Ah
Charge / discharge 100 A / 60 A (cont.), 130 A (5 s) pulse
Round-trip efficiency >98%
Enclosure IP65; wall/rack/floor mount
Dimensions (L×W×H) 21.5″ × 17.5″ × 7.2″
Weight ≈116 lb
Temperature (charge / discharge) 32–113 °F / 32–140 °F
Cycle life ~8,000 @ 80% DoD

Choose the Fortress eFlex 5.4 kWh battery for compact, reliable storage that’s easy to expand and simple to integrate with most 48 V hybrid inverters.

What Makes the Fortress eFlex 5.4 kWh Battery Stand Out?

The Fortress eFlex 5.4 kWh battery is designed with premium lithium iron phosphate chemistry, ensuring exceptional safety, thermal stability, and a long cycle life. Unlike conventional battery technologies, LFP batteries are non-toxic, highly stable, and resistant to overheating, making them ideal for residential and indoor installations.

This unit is officially listed as Fortress Power LFP battery 105 AH 5.4kWh total capacity max. 10 year warranty A14 Wall mount bracket included - eFlex 5.4 kWh, highlighting its robust capacity and extended warranty support.

With 105Ah capacity and 5.4kWh usable energy, the system provides dependable power for essential appliances, home energy storage, or solar self-consumption. Its intelligent design ensures smooth charging and discharging cycles without compromising performance.

Advanced Performance with LFP Battery Technology

Lithium iron phosphate (LFP) technology is widely recognized for its safety and longevity. The Fortress eFlex battery leverages this chemistry to offer:

  • Superior thermal stability
  • Long cycle life with minimal degradation
  • High depth of discharge without reducing lifespan
  • Consistent performance in varying load conditions

The integrated BMS continuously monitors voltage, temperature, and current, protecting the battery from overcharging, over-discharging, and short circuits. This ensures stable operation and maximizes battery efficiency across daily use.

Scalable Design for Growing Energy Needs

One of the major advantages of the Fortress eFlex 5.4 kWh battery is its scalability. Users can connect multiple units in parallel to expand total storage capacity as energy demands increase. This makes it a future-ready solution for homeowners planning to add solar panels, EV chargers, or additional backup circuits.

The modular architecture allows easy system expansion without replacing existing batteries. As energy consumption grows, the system adapts effortlessly.

Easy Installation with Wall-Mount Bracket Included

Installation convenience is another strong benefit of this battery system. The A14 wall-mount bracket is included, allowing secure and space-efficient mounting. The compact form factor enables installation in garages, utility rooms, or dedicated battery enclosures.

Clear connection points and standardized compatibility make integration with hybrid and off-grid inverters straightforward. This reduces installation time while maintaining a clean and professional setup.

Long-Term Reliability with 10-Year Warranty

The Fortress eFlex system is backed by a maximum 10-year warranty, reinforcing confidence in its durability and performance. This long warranty period reflects the quality of components used and the manufacturer’s commitment to long-term customer satisfaction.

With proper installation and usage, the battery is designed to deliver reliable power storage over thousands of cycles, making it a dependable long-term investment for energy security.

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What is your return policy?

Returns are free in the first 30 days with no restocking or processing fees, although the customer may be responsible for paying return shipping. See our complete return policy on our Shipping, Delivery, and Returns page linked in the footer of this website.

What’s covered by your return policy?

Our returns policy covers all purchases made through Portlandia Electric Supply. For warranty issues, as authorized distributors, we honor the full manufacturer warranty of ALL the brands on our website. See our complete returns and warranty policies on our Shipping, Deliver, and Returns page.

How long will it take to receive my order?

All orders are processed within 72 hours and you can expect delivery on most orders within 5-7 business days. You will receive access to our customer portal after ordering, where it is easy to track all your shipments. See our Shipping, Delivery and Returns page for more details.

What are your financing and payment options?

We offer several ways to pay to make getting your solar kit simple:

Credit Card: if the purchase is greater than your card’s limit, you can split the cost onto multiple cards as well as Paypal, financing through Affirm, and ACH/bank transfer

You can arrange financing during the checkout process, or scroll further down this page for more details. Please note, if you'd like to finance your order, you can do so instantly, right at checkout.

How does your Lifetime Customer Support work?

Our legendary lifetime customer support has helped make us the #1 online solar retailer! We have a dedicated team of solar professionals standing by to help you navigate the world of solar with ease. From selecting the perfect solar kit to installation and beyond, we provide support and expertise at every step of the journey.If you need help with ordering, shipping, troubleshooting, expanding your system, warranty issues, or anything else you have questions about for as long as you own your Portlandia Electric Supply equipment, we’ve got you covered: we’re always only a phone call or email away.

Fortress eFlex 5.4 kWh battery — 48 V LiFePO₄ module (IP65)

The Fortress eFlex 5.4 kWh battery is a modern lithium iron phosphate (LFP) energy storage solution designed for homeowners and small commercial users who demand safety, performance, and long-term reliability. Built with advanced battery technology, this system delivers consistent power backup, seamless solar integration, and flexible installation options to meet today’s growing energy needs.

As energy independence becomes more important, the Fortress eFlex system stands out with its durable construction, intelligent battery management system (BMS), and scalable design. Whether used for backup power or daily energy optimization, this battery is engineered to perform efficiently for years.

Fortress eFlex 5.4 kWh battery is a compact, safe LFP pack (48 V, 105 Ah) with Wi-Fi/RS485/CAN comms and an IP65 outdoor enclosure—for fast installation with wall, rack, or floor mounting.

Key features

Fortress eFlex 5.4 kWh battery works with closed-loop 48 V inverters; BMS provides cell-level monitoring, 8,000-cycle life, and >98% RTE.

  • 5.4 kWh energy · 48–55 V operating · 105 Ah capacity
  • Max charge 100 A · max discharge 60 A · 130 A (5 s) pulse
  • IP65 enclosure; wall/rack/floor mounting options
  • Comms: RS485, CAN, Wi-Fi (OTA updates)
  • Round-trip efficiency >98%; life: ~8,000 cycles @ 80% DoD

Specifications

Fortress eFlex 5.4 kWh battery — specification box
Total energy 5.4 kWh
Nominal / operating V 48 V / 48–55 V
Capacity 105 Ah
Charge / discharge 100 A / 60 A (cont.), 130 A (5 s) pulse
Round-trip efficiency >98%
Enclosure IP65; wall/rack/floor mount
Dimensions (L×W×H) 21.5″ × 17.5″ × 7.2″
Weight ≈116 lb
Temperature (charge / discharge) 32–113 °F / 32–140 °F
Cycle life ~8,000 @ 80% DoD

Choose the Fortress eFlex 5.4 kWh battery for compact, reliable storage that’s easy to expand and simple to integrate with most 48 V hybrid inverters.

What Makes the Fortress eFlex 5.4 kWh Battery Stand Out?

The Fortress eFlex 5.4 kWh battery is designed with premium lithium iron phosphate chemistry, ensuring exceptional safety, thermal stability, and a long cycle life. Unlike conventional battery technologies, LFP batteries are non-toxic, highly stable, and resistant to overheating, making them ideal for residential and indoor installations.

This unit is officially listed as Fortress Power LFP battery 105 AH 5.4kWh total capacity max. 10 year warranty A14 Wall mount bracket included - eFlex 5.4 kWh, highlighting its robust capacity and extended warranty support.

With 105Ah capacity and 5.4kWh usable energy, the system provides dependable power for essential appliances, home energy storage, or solar self-consumption. Its intelligent design ensures smooth charging and discharging cycles without compromising performance.

Advanced Performance with LFP Battery Technology

Lithium iron phosphate (LFP) technology is widely recognized for its safety and longevity. The Fortress eFlex battery leverages this chemistry to offer:

  • Superior thermal stability
  • Long cycle life with minimal degradation
  • High depth of discharge without reducing lifespan
  • Consistent performance in varying load conditions

The integrated BMS continuously monitors voltage, temperature, and current, protecting the battery from overcharging, over-discharging, and short circuits. This ensures stable operation and maximizes battery efficiency across daily use.

Scalable Design for Growing Energy Needs

One of the major advantages of the Fortress eFlex 5.4 kWh battery is its scalability. Users can connect multiple units in parallel to expand total storage capacity as energy demands increase. This makes it a future-ready solution for homeowners planning to add solar panels, EV chargers, or additional backup circuits.

The modular architecture allows easy system expansion without replacing existing batteries. As energy consumption grows, the system adapts effortlessly.

Easy Installation with Wall-Mount Bracket Included

Installation convenience is another strong benefit of this battery system. The A14 wall-mount bracket is included, allowing secure and space-efficient mounting. The compact form factor enables installation in garages, utility rooms, or dedicated battery enclosures.

Clear connection points and standardized compatibility make integration with hybrid and off-grid inverters straightforward. This reduces installation time while maintaining a clean and professional setup.

Long-Term Reliability with 10-Year Warranty

The Fortress eFlex system is backed by a maximum 10-year warranty, reinforcing confidence in its durability and performance. This long warranty period reflects the quality of components used and the manufacturer’s commitment to long-term customer satisfaction.

With proper installation and usage, the battery is designed to deliver reliable power storage over thousands of cycles, making it a dependable long-term investment for energy security.

Customer Reviews

Be the first to write a review
0%
(0)
0%
(0)
0%
(0)
0%
(0)
0%
(0)

What is your return policy?

Returns are free in the first 30 days with no restocking or processing fees, although the customer may be responsible for paying return shipping. See our complete return policy on our Shipping, Delivery, and Returns page linked in the footer of this website.

What’s covered by your return policy?

Our returns policy covers all purchases made through Portlandia Electric Supply. For warranty issues, as authorized distributors, we honor the full manufacturer warranty of ALL the brands on our website. See our complete returns and warranty policies on our Shipping, Deliver, and Returns page.

How long will it take to receive my order?

All orders are processed within 72 hours and you can expect delivery on most orders within 5-7 business days. You will receive access to our customer portal after ordering, where it is easy to track all your shipments. See our Shipping, Delivery and Returns page for more details.

What are your financing and payment options?

We offer several ways to pay to make getting your solar kit simple:

Credit Card: if the purchase is greater than your card’s limit, you can split the cost onto multiple cards as well as Paypal, financing through Affirm, and ACH/bank transfer

You can arrange financing during the checkout process, or scroll further down this page for more details. Please note, if you'd like to finance your order, you can do so instantly, right at checkout.

How does your Lifetime Customer Support work?

Our legendary lifetime customer support has helped make us the #1 online solar retailer! We have a dedicated team of solar professionals standing by to help you navigate the world of solar with ease. From selecting the perfect solar kit to installation and beyond, we provide support and expertise at every step of the journey.If you need help with ordering, shipping, troubleshooting, expanding your system, warranty issues, or anything else you have questions about for as long as you own your Portlandia Electric Supply equipment, we’ve got you covered: we’re always only a phone call or email away.

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Prepare for Anything

From hurricanes to blackouts, reliable solar power ensures you're able to keep your home & family safe no matter what comes your way.

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Making one-click solar solutions simple since 2018. Whether you’re powering a cabin, charging devices, or backing up your home.

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Say goodbye to reliance on the energy companies. Enjoy the same freedom that 50,000+ customers have with their own solar power system.

Customer Success Stories

Troy P

EG4 off-grid base kit, Happy with my purchase.

This is the first stage of my three planned purches. I got the eg4 inverter 6000 XP base kit with six 400 watt panels and the two server rack batteries. Did a little online research and followed the instructions and it got set up without any issues. Right now I'm just running it in my garage on a single outlet and have been running dual 750 watt water distillers with it. Once I get the second inverter and a bunch more panels and batteries, I plan on attaching it to my subpanel in my house that has my lights and outlets and appliances on it. Then I'll get a soft start for my AC and blower and run it on my main panel.

Jacob B

Easy Process, Genuine Support

Trying to pick the correct solar system for your needs can be very technical and frustrating. I wanted to thank Yvhan and the Portlandia Electric supply team for their patience and helpful attitudes through multiple calls. I feel like we were able to narrow it down to what worked for me and my family. My system works great and I couldn't be happier to have picked Portlandia Electric Supply.

Patrick B

Off Grid Solar Purchase

I wanted to get an offgrid solar system for years but didn’t know where to start. I found Portlandia Electric Supply on Facebook and decided to submit a quote. Within 24 hours I had a custom proposal that was almost half the price of the companies I had previously got quotes from. My wife and I decided to order online and the kit came in a timely manner and it was an easy install. Great company to work with!

James Martin

Highly Recommend

I would like to take the time to express the outstanding service that I was provided with by Portlandia Electric Supply. They provided me with all the answers to my questions, and after reviewing our quote over the phone I felt comfortable proceeding to order my kit. It’s exactly what I needed and they were there to help us over the phone when we had questions installing it. I highly recommend others in need to choose Portlandia Electric Supply.

Brian H

Solar Kit for Mobile Work Van

As a professional videographer, I needed reliable power on the go.Portlandia Electric Supply Delta Pro and roof-mounted panels were the perfect solution. Setup was easy, and the kit included everything needed. The Delta Pro powers my cameras, lights, laptop, and a small fridge with impressive battery capacity.

Keith S

Best Tech Support

You folks have been wonderful guiding me through the ins and outs of going solar. Plus your tech guys Rod and Nelson are the absolute best. They explained all the different aspects of inverters, batteries and how to keep them in top condition. Too much more to put here… but no other company has the 100% tech support you provide for your customers!

Coll A

Great Experience

My experience with Portlandia Electric Supply has been excellent. Before the sales, they answered all my questions to assure that I got what I needed. After the sales they continued to support me with answers and help. I had a warranty issue with a unit, and it was handled as well as possible. I would recommend them to anyone looking to go solar.

Troy P

EG4 off-grid base kit, Happy with my purchase.

This is the first stage of my three planned purches. I got the eg4 inverter 6000 XP base kit with six 400 watt panels and the two server rack batteries. Did a little online research and followed the instructions and it got set up without any issues. Right now I'm just running it in my garage on a single outlet and have been running dual 750 watt water distillers with it. Once I get the second inverter and a bunch more panels and batteries, I plan on attaching it to my subpanel in my house that has my lights and outlets and appliances on it. Then I'll get a soft start for my AC and blower and run it on my main panel.

Jacob B

Easy Process, Genuine Support

Trying to pick the correct solar system for your needs can be very technical and frustrating. I wanted to thank Yvhan and the Portlandia Electric supply team for their patience and helpful attitudes through multiple calls. I feel like we were able to narrow it down to what worked for me and my family. My system works great and I couldn't be happier to have picked Portlandia Electric Supply.

Patrick B

Off Grid Solar Purchase

I wanted to get an offgrid solar system for years but didn’t know where to start. I found Portlandia Electric Supply on Facebook and decided to submit a quote. Within 24 hours I had a custom proposal that was almost half the price of the companies I had previously got quotes from. My wife and I decided to order online and the kit came in a timely manner and it was an easy install. Great company to work with!

James Martin

Highly Recommend

I would like to take the time to express the outstanding service that I was provided with by Portlandia Electric Supply. They provided me with all the answers to my questions, and after reviewing our quote over the phone I felt comfortable proceeding to order my kit. It’s exactly what I needed and they were there to help us over the phone when we had questions installing it. I highly recommend others in need to choose Portlandia Electric Supply.

Brian H

Solar Kit for Mobile Work Van

As a professional videographer, I needed reliable power on the go.Portlandia Electric Supply Delta Pro and roof-mounted panels were the perfect solution. Setup was easy, and the kit included everything needed. The Delta Pro powers my cameras, lights, laptop, and a small fridge with impressive battery capacity.

Keith S

Best Tech Support

You folks have been wonderful guiding me through the ins and outs of going solar. Plus your tech guys Rod and Nelson are the absolute best. They explained all the different aspects of inverters, batteries and how to keep them in top condition. Too much more to put here… but no other company has the 100% tech support you provide for your customers!

Coll A

Great Experience

My experience with Portlandia Electric Supply has been excellent. Before the sales, they answered all my questions to assure that I got what I needed. After the sales they continued to support me with answers and help. I had a warranty issue with a unit, and it was handled as well as possible. I would recommend them to anyone looking to go solar.

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Shop Securely, Trusted Supplier, 100% Satisfaction

Trusted Company, Real Products, Lifetime Support

Avoid Scams, Buy with Confidence, Enjoy Peace of Mind

Manufacturer Warranty, Exceptional Service

Be Smart, Buy From an Authorized Dealer

When you choose Portlandia Electric Supply, you’re buying real products from a trusted company with established supplier relationships. Enjoy peace of mind with 100% manufacturer warranty coverage and lifetime customer support. In an age where online shopping is fraught with risks, it’s crucial to avoid fly-by-night websites that skirt regulations. Shop with confidence, knowing you’re getting genuine quality and reliable service.

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