Fortress Power eFlex MAX 5.4kWh Lithium Solar Battery
🔋⛰️ Rugged, Long-lasting, Daily Use Battery
Stay powered at home, on the road, or off the grid.
The eFlex MAX 5.4kWh is a durable 48V lithium battery designed for maximum flexibility and long-term energy savings. Whether you’re living in a city apartment, a remote cabin, or traveling in an RV or boat, it delivers reliable backup power whenever you need it.
With 8,000+ life cycles, a 10-year warranty, and built-in safety protections, the eFlex MAX is built to last. Use it for solar storage, emergency backup, or off-grid living — it’s the versatile energy solution that adapts to your lifestyle.
Applications
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Off-grid homes and cabins
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Home backup power
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RVs & Adventure
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DIY solar setups
Introduction to the Fortress Power eFlex MAX 5.4kWh LFP Battery
eFlex MAX 5.4kWh Battery Features
A compact 48V LFP battery with closed-loop inverter integration, advanced communications, and DIY-friendly design — ideal for scalable residential systems.
🌦️ Durable, Outdoor-Ready Design
Saltwater-resistant
aluminum shell protects your power anywhere — no bulky housing needed. Perfect for homes, cabins, RVs, and boats.
🔋 10+Years of Reliable Energy
Enjoy over 8,000 cycles of worry-free use. Built with a patented aluminum shell for
better cooling and long-lasting durability.
✅More Power, Less Waste
The eFlex MAX operates at up to 99% round-trip efficiency and consumes just 2W in idle mode, making it ideal for off-grid systems and maximizing energy savings.
↗️ Easily Expand as You Grow
Parallel and connect units in minutes. No messy wiring, no hassle — just more power when you need it.
🛠️Quick, Flexible Installation, Indoors or Out
Wall or floor mount, indoors or outdoors.
Waterproof design for clean, code-compliant installs without extra parts.
💵 Maximum Value, Minimum Cost per kWh
Cutting-edge LFP technology with high output at a cost that makes sense. Save more over the system’s lifetime.
💵 VPP-Ready for Grid Incentives
Approved for Virtual Power Plant (VPP) programs nationwide, enabling customers to earn revenue and support grid reliability with intelligent energy discharge.
eFlex Max Installation Videos
Step-by-step setup guide.
eFlex Max Influencer Videos
Hear what influencers think.
eFlex Max Real World Installations
Discover real-world installations of the eFlex MAX battery in homes, municipal facilities, and DIY solar projects.
📍 Todos Santos, Baja California Sur
🏠 Installation Type:
Homeowner Install
⚡ System Specs:
12 kW / 7.28 kWh
📍 El Sargento, Baja California Sur
🏠 Installation Type:
DIY install at an off-grid desert home
⚡ System Specs:
10kW / 16.2 kWh
📍Puerto Rico
🏠 Installation Type:
Isabela’s Municipal Multi Use Center-
⚡ System Specs:
208V Three-Phase
36kW / 64.8 kWh
eFlex MAX 5.4kWh Battery Technical Specs & Downloads
Get the details you need—spec sheets, manuals, and performance data all in one place. We link directly to the manufacturer's site, so you know you always have the most up-to-date information.
| General | |
| Name | eFlex MAX 5.4 |
| Total Energy(kWh) | 5.4 |
| Max. Charge Current (Continuous) [A] | 100 |
| Max. Discharge Current (Continuous) [A] | 100 |
| Nominal Capacity [Ah] | 105 |
| Voltage Range [V] | 48-55 |
| Charging Temperature [F] | 32 ~ 114 |
| Discharging Temperature [F] | -4 ~ 131 |
| Storage Temperature [F] | 20 ~ 95 |
| Dimension [L x W x H, inch] | 17.5 x 24.2 x 7.2 |
| Weight [lbs] | 108 |
| Life Cycles | 8000 @ 80% DoD |
| Round Trip Efficiency | >98% |
