Fortress Power eForce 28.8kWh Stackable Outdoor Battery System

28.8kWh · 48V · Stackable Fortress Power eForce 28.8kWh Stackable Outdoor Battery System The eForce 28.8kWh delivers 600Ah from Tier-1 prismatic LiFePO4 cells rated for 8,000 cycles, with a built-in 125W heater for reliable charging in cold conditions and an IP65-sealed enclosure for outdoor installation. It communicates over RS485, Wi-Fi, or CAN with compatible Fortress Power inverters, and stacks with other eForce units for up to 268.8kWh in one system. 10-Year Warranty Lowest Price Guarantee Authorized Fortress Power Dealer Free Shipping 0% APR Financing Expert Support: (303) 876-7654 Why the eForce 8,000 Cycles to 70% End of Life Tier-1 prismatic LiFePO4 cells rated for 8,000 cycles to 70% end-of-life capacity. Integrated 125W Heating Element Built-in heating activates between -4°F and 41°F depending on state of charge, extending usable range into cold climates without a separate heated enclosure. IP65, -4°F to 140°F Rated Sealed IP65 enclosure rated across a wide -4°F to 140°F ambient temperature range. Stack Up to 268.8kWh Stack up to 3 modules vertically, or parallel laterally for up to 268.8kWh in one system, depending on configuration. RS485 / Wi-Fi / CAN Communication Communicates over RS485, Wi-Fi, or CAN for pairing with a compatible hybrid inverter and Fortress Power's monitoring app. UL9540 / UL9540A Listed Certified to UL1741, UL1973, UL9540, UL9540A, and UN38.3 — the standards that matter for a residential energy storage installation. What's Included What You Get 1 × Fortress Power eForce 28.8kWh Stackable Outdoor Battery System Documentation eWay/base storage system and inverter sold separately. Full Specifications Model Fortress Power eForce 28.8kWh Nominal Voltage 48V (operating range 39–54V) Capacity 600Ah / 28.8kWh Battery Chemistry Tier-1 Prismatic LiFePO4 (15-cell) Nominal Charge/Discharge Current 120A / 160A Max Charge/Discharge Current 195A / 195A (up to 250A when vertically stacked) Cycle Life 8,000 cycles to 70% end of life Ambient Temperature Range -4°F to 140°F (-20°C to 60°C) Integrated Heater 125W; activates -4°F to 41°F depending on state of charge; do not charge below -4°F Weight 681 lb Dimensions 24.4"D × 9.4"W × approx. 33.5"H (scales with module height) Ingress Protection IP65 Communication RS485 / Wi-Fi / CAN Max Stacking Up to 3 modules vertically, or laterally up to 268.8kWh (max parallel units vary by configuration: 16/8/5) Round-Trip Efficiency Not published by Fortress Power for this model Warranty 10 years standard (Fortress Power also advertises up to a 15-year warranty when purchased as a complete eForce system — confirm which applies to your order) Certifications UL1741, UL1973, UL9540, UL9540A, UN38.3 Authorized Fortress Power Dealer We sell genuine Fortress Power products backed by Fortress Power's own warranty. Lowest Price Guarantee Find it cheaper from another authorized dealer? Call (303) 876-7654 before you order. Real Support, Not a Ticket Queue Sizing a system or checking inverter compatibility? Call (303) 876-7654 and talk to a person. Fortress Power eForce 28.8kWh Stackable Outdoor Battery System: Frequently Asked Questions Does this need a heater in cold climates, or is one built in? It has a built-in 125W heating element that activates automatically between -4°F and 41°F depending on state of charge — no separate enclosure heater needed. Fortress Power still specifies not to attempt charging below -4°F. How many of these can I stack together? Up to 3 modules vertically, or more laterally for up to 268.8kWh total depending on your configuration — the maximum number of parallel units varies by setup (16, 8, or 5 depending on configuration). Call (303) 876-7654 and we can help you plan a specific system size. What's the actual warranty — 10 years or 15? Fortress Power's standard warranty on the eForce line is 10 years. They also advertise up to a 15-year warranty when the battery is purchased as part of a complete eForce system — call (303) 876-7654 and we'll confirm which warranty term applies to your specific order before you buy. What inverters does this work with? Fortress Power's Envy 8/10kW, Envy True 12kW, Envy Duo 21, and compatible hybrid inverters. Confirm compatibility with your specific setup — call (303) 876-7654 if you're not sure. Can I install this myself, or do I need an electrician? Fortress Power's equipment is designed for professional installation. We strongly recommend a licensed electrician or solar installer for any battery, inverter, or enclosure installation — call (303) 876-7654 if you need a referral in your area. Do you offer financing or price matching? Yes. We offer 0% APR financing options through Affirm at checkout, and our Lowest Price Guarantee applies — if you find this product cheaper at another authorized Fortress Power dealer, call us at (303) 876-7654 before you order and we'll take care of it.