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Fortress eVault Max 18.5 kWh Lithium Battery Storage

Fortress Power Fortress eVault Max 18.5 kWh Lithium Battery Storage

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SKU PES-ESS-BTS-0275

Fortress eVault Max 18.5 kWh Lithium Battery Storage

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Get yours today!

9+ sold

In the last 7 days

Flat Rate Shipping - Calculated at Checkout

Delivery timeframe shown above at checkout

Lifetime Customer Support

Unlimited lifetime support, always available.

In High Demand! Order Now To Secure Your Items

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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 eVault Max 18.5 Battery - 18.5 kWh 48 V Module

18.5 kWh

Single-Unit Capacity

8,000

Cycle Life @ 80% DoD

98%

Round-Trip Efficiency

370 kWh

Scalable Parallel System

Product Overview

The Fortress eVault Max 18.5 battery is a high-capacity 48 V lithium iron phosphate storage module designed for whole-home backup, self-consumption, peak shaving, and light-commercial energy resilience. With 18.43 kWh of rated capacity in a single enclosure, the eVault Max can support substantial critical loads without requiring an external combiner cabinet, making it a practical choice for applications where a large single battery block simplifies installation and system layout. Its compact tower form factor integrates the battery, BMS, communications, and service access into one purpose-built package.

Built around tier-1 prismatic LiFePO₄ cells and an intelligent battery management system, the eVault Max is engineered for long service life, high efficiency, and dependable operation over thousands of charge cycles. The enclosure is serviceable from the top, and built-in wheels help installers position the unit more easily during setup and maintenance.

Key Benefits

Massive Single-Unit Capacity: At 18.5 kWh, one eVault Max 18.5 battery can carry a meaningful portion of a home or small business backup load on its own, reducing the need for multiple small modules or an external battery cabinet.

8,000-Cycle Longevity: Tier-1 prismatic LiFePO₄ cells and an intelligent BMS help the battery achieve long cycle life at 80% depth of discharge, supporting durable day-to-day storage use.

Installer-Friendly Top Access: The serviceable top cover and built-in wheels make the unit easier to place, inspect, and service while keeping the enclosure compact and floor-standing.

High Efficiency and Safe Chemistry: The LiFePO₄ chemistry and high round-trip efficiency help the battery deliver reliable energy storage with strong thermal stability and low losses.

Scalable Platform: The eVault Max can be expanded in parallel to serve larger residential or light-commercial systems, allowing the storage capacity to grow with the project.

How It Works

The Fortress eVault Max stores energy in its internal LiFePO₄ cell stack and manages charge and discharge through the integrated battery management system. During normal operation, it can be charged from solar or other compatible sources, then discharge stored energy to support critical loads, reduce grid dependence, or provide backup power during outages. Its CAN and RS-485 communications allow it to integrate with compatible inverter systems for coordinated energy management.

Battery Management System: The internal BMS monitors cell behavior, charging, and discharge limits to help protect the battery and maintain performance.

Energy Delivery: The battery supports continuous and surge discharge rates sized for critical loads, backup, and demand reduction applications.

System Integration: Communication through CAN or RS-485 helps the battery work with supported inverter and energy control platforms.

Technical Specifications

Nominal Voltage	51.2 V DC
Nominal Capacity	360 Ah / 18.43 kWh
Round-Trip Efficiency	98%
Recommended Continuous Discharge	180 A (9.2 kW)
Surge Discharge	250 A (12.8 kW, 5 s)
Cycle Life	8,000 Cycles @ 80% DoD
Depth of Discharge	Up to 100%
Dimensions (L × W × H)	20.3 × 20.3 × 42.2 in (515 × 515 × 1,073 mm)
Weight	520 lb (236 kg)
Operating Temperature (Discharge)	−4 °F to +140 °F (−20 °C to +60 °C)
Ingress Protection	IP55
Communications	CAN & RS-485
Certifications	UL 1642, UL 1973, UL 9540, UL 9540A, UN 38.3
Warranty	10 Years

Installation & Warranty

A 10-year manufacturer warranty and IP55 enclosure support reliable indoor-safe deployment for years of whole-home and light-commercial use. The serviceable top access and compact tower footprint make the eVault Max easier to install and maintain than many larger multi-cabinet battery systems.

Documentation

📄Datasheet 🛠️Installation Manual

● Available | Order now and power your future with clean energy!

What is your return policy?

What’s covered by your return policy?

How long will it take to receive my order?

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?

Fortress eVault Max 18.5 Battery - 18.5 kWh 48 V Module

18.5 kWh

Single-Unit Capacity

8,000

Cycle Life @ 80% DoD

98%

Round-Trip Efficiency

370 kWh

Scalable Parallel System

Product Overview

Key Benefits

8,000-Cycle Longevity: Tier-1 prismatic LiFePO₄ cells and an intelligent BMS help the battery achieve long cycle life at 80% depth of discharge, supporting durable day-to-day storage use.

Installer-Friendly Top Access: The serviceable top cover and built-in wheels make the unit easier to place, inspect, and service while keeping the enclosure compact and floor-standing.

High Efficiency and Safe Chemistry: The LiFePO₄ chemistry and high round-trip efficiency help the battery deliver reliable energy storage with strong thermal stability and low losses.

Scalable Platform: The eVault Max can be expanded in parallel to serve larger residential or light-commercial systems, allowing the storage capacity to grow with the project.

How It Works

Battery Management System: The internal BMS monitors cell behavior, charging, and discharge limits to help protect the battery and maintain performance.

Energy Delivery: The battery supports continuous and surge discharge rates sized for critical loads, backup, and demand reduction applications.

System Integration: Communication through CAN or RS-485 helps the battery work with supported inverter and energy control platforms.

Technical Specifications

Nominal Voltage	51.2 V DC
Nominal Capacity	360 Ah / 18.43 kWh
Round-Trip Efficiency	98%
Recommended Continuous Discharge	180 A (9.2 kW)
Surge Discharge	250 A (12.8 kW, 5 s)
Cycle Life	8,000 Cycles @ 80% DoD
Depth of Discharge	Up to 100%
Dimensions (L × W × H)	20.3 × 20.3 × 42.2 in (515 × 515 × 1,073 mm)
Weight	520 lb (236 kg)
Operating Temperature (Discharge)	−4 °F to +140 °F (−20 °C to +60 °C)
Ingress Protection	IP55
Communications	CAN & RS-485
Certifications	UL 1642, UL 1973, UL 9540, UL 9540A, UN 38.3
Warranty	10 Years

Installation & Warranty

Documentation

📄Datasheet 🛠️Installation Manual

● Available | Order now and power your future with clean energy!

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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.