Product Description

The BigBattery ETHOS is a stackable 48V LiFePO4 home battery system. This listing is BigBattery part K0950: a 15.36 kWh tower built from three 5.12 kWh ETHOS modules — 300Ah at 51.2V nominal in a 16S3P configuration, per BigBattery's ETHOS spec sheet. Per BigBattery, ETHOS carries UL9540, UL9540A, UL1973, and UN38.3 certifications, communicates over CAN bus/RS485, and supports closed-loop communication with compatible EG4 inverters. It is the same battery platform used across our BigBattery ETHOS kits.

Who This System Is For

Homeowners adding storage to a new or existing 48V solar installation, and anyone building backup power where the permitting office asks for UL-listed equipment. The vertical tower keeps the footprint to roughly 26.5 inches wide by 6.7 inches deep, and capacity grows in 5.12 kWh steps, so it fits essential-circuit backup today with room to expand later. Pair it with a hybrid inverter such as the EG4 18kPV for grid-tied service, or with EG4's XP-series inverters for off-grid systems — see our EG4 collection.

Key Features

  • 15.36 kWh of LiFePO4 storage — three stacked 5.12 kWh / 100Ah modules (16S3P), per BigBattery's ETHOS spec sheet
  • Certified for residential energy storage: UL9540, UL9540A, UL1973, and UN38.3, per BigBattery
  • 250A maximum continuous discharge (12,800W) and 200A maximum charge current for this three-module configuration, per BigBattery
  • Stackable and expandable — per BigBattery, up to 16 parallel connections per control box, so capacity can grow in 5.12 kWh steps
  • Closed-loop communication with compatible EG4 inverters over CAN bus/RS485, per BigBattery
  • 3,500–5,000 cycle life at 80% depth of discharge, 0.5C, per BigBattery's spec sheet
  • IP65-rated module enclosures with a battery management system (BMS) in every module

Why BigBattery

BigBattery is a US-based energy storage company that has been building lithium battery systems since 2011 and, per BigBattery, is trusted by more than 50,000 Americans. BigBattery states its products are designed and engineered in Texas, and every BigBattery product includes free lifetime tech support and troubleshooting from its US-based team. The company backs its batteries with a 12-Year Limited Warranty, which BigBattery describes as "the longest warranty in the battery industry." OffGrid Horizon is a family-owned authorized BigBattery partner.

What's In the Kit

  • 3 × BigBattery ETHOS 48V 5.12 kWh LiFePO4 modules, assembled as one 15.36 kWh stacked tower
  • Integrated BMS in each module with CAN bus/RS485 communication

BigBattery lists ETHOS inverter connectors and battery-to-battery connectors as separate accessories, and base/control-box hardware varies by configuration — please call (302) 496-3554 to confirm the exact accessories included with your order.

Specifications

SKU K0950
Chemistry LiFePO4 (lithium iron phosphate)
Nominal voltage 51.2V (48V-class system)
Capacity 15.36 kWh / 300Ah (3 × 5.12 kWh / 100Ah modules, 16S3P)
Max continuous discharge 250A (12,800W), per BigBattery
Peak discharge 300A, max 5 seconds, per BigBattery
Max charge current 200A; charge voltage 55.6–57V
Communications CAN bus / RS485; closed-loop with compatible EG4 inverters, per BigBattery
Charge temperature 32°F to 113°F
Discharge temperature -4°F to 140°F
Dimensions (3-module tower) 26.5" W × 6.7" D × 59.8" H, per BigBattery
Weight (3-module tower) 387 lb, per BigBattery
Enclosure IP65
Cycle life 3,500–5,000 cycles (80% DoD, 0.5C), per BigBattery's spec sheet
Certifications UL9540, UL9540A, UL1973, UN38.3, per BigBattery
Expandability Up to 16 parallel connections per control box, per BigBattery
Warranty BigBattery 12-Year Limited Warranty (accessories 1 year)

Grid-Tied, Off-Grid, or Backup?

ETHOS is the battery — system capability comes from the inverter you pair with it. Per BigBattery, ETHOS is compatible with grid-tied UL9540 configurations built on the EG4 18kPV, FlexBOSS18, and FlexBOSS21 hybrid inverters (grid export is subject to utility interconnection approval), and with off-grid inverters including the EG4 6000XP and 12000XP. With a hybrid inverter, ETHOS can back up selected circuits or, with sufficient inverter output and load management, larger portions of a home — actual coverage depends on your loads.

Installation

Module stacking and placement are straightforward, but all DC and AC wiring — inverter connection, panel interconnection, grounding, bonding, and overcurrent protection — must be performed by a licensed electrician in accordance with the National Electrical Code (NEC) and local amendments. Residential energy storage installations typically require a permit and inspection, and grid-tied systems require an approved interconnection agreement with your utility before exporting power. Your installer should verify conductor sizing, disconnects, and clearances against current NEC requirements for energy storage systems.

Warranty & Support

BigBattery 12-Year Limited Warranty. Per BigBattery: "If any covered component within your battery fails due to a defect in materials or workmanship within the 12-year warranty period, we will repair or replace the battery at our cost." Included accessories such as cables and connectors carry a 1-year warranty per BigBattery, and BigBattery provides free lifetime tech support and troubleshooting for all BigBattery products.

Returns and warranty claims require an RMA. Please contact us before shipping anything back — all returns must be authorized with a Return Merchandise Authorization first. OffGrid Horizon is a family-owned authorized BigBattery partner: call (302) 496-3554 and we will help open the claim and coordinate service with BigBattery.

Shipping

This system ships as palletized LTL freight within the continental United States; curbside liftgate delivery is standard for residential addresses. The three-module tower weighs 387 lb, so plan for help moving it into place. Before signing the delivery receipt, count the pieces and inspect the packaging — note any visible damage or shortage on the receipt with the driver and contact us right away so we can open a freight claim. Per BigBattery, standard domestic orders are projected to take 7–12 days to deliver.

Frequently Asked Questions

Can I expand this system later?

Yes. ETHOS is a stacking platform — per BigBattery, up to 16 parallel connections per control box — so you can add 5.12 kWh modules as your needs grow instead of buying maximum capacity up front.

Which inverters work with ETHOS?

Per BigBattery: the EG4 18kPV, FlexBOSS18, and FlexBOSS21 for grid-tied UL9540 configurations, and off-grid inverters including the EG4 6000XP and 12000XP. Closed-loop communication is supported with compatible EG4 models.

Will it charge in cold weather?

Per BigBattery's spec sheet, the charge temperature range is 32°F to 113°F and discharge is rated to -4°F. The BMS restricts charging below freezing to protect the cells, so install the tower in an insulated or conditioned space if winters are cold.

Is 15.36 kWh enough to back up my whole house?

That depends on your loads. 15.36 kWh typically carries refrigeration, lighting, electronics, and other essentials through an evening or overnight outage; whole-home coverage depends on which circuits you back up, your inverter's output rating, and how long the outage lasts.

Do the UL listings matter for permitting?

Many building departments request UL1973 and UL9540A documentation when permitting residential energy storage. Per BigBattery, ETHOS carries UL9540, UL9540A, UL1973, and UN38.3.

What if I need warranty service?

Contact us first — warranty claims and returns require an RMA, and we will help you open a claim ticket with BigBattery and coordinate next steps.

Questions about sizing, inverter pairing, or expansion? Call OffGrid Horizon at (302) 496-3554 — we're a family-owned authorized BigBattery partner and happy to help you spec it right.

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