Product Description

The EG4 WallMount 314Ah Indoor is a 48V-class (51.2V nominal) LiFePO4 battery delivering 16 kWh of nominal storage in a wall- or floor-mounted unit built for garages, basements, and utility rooms. Per EG4 it is certified to UL1973 with UL9540A fire-safety test data, forms a UL9540 system with the FlexBOSS21 and FlexBOSS18 inverters, and includes self-heating so unheated spaces keep charging through winter. OffGrid Horizon is a family-owned authorized EG4 dealer, and every unit ships with full manufacturer warranty support.

Who This Is For

This is the battery for homeowners installing storage indoors — especially in cold climates, where the internal heater keeps charging available in unconditioned garages, and in jurisdictions where UL9540A test documentation and a UL9540 system pairing smooth the permitting conversation. At 293.2 lb it is the lightest 16 kWh unit in the WallMount line, and it is the same battery included in our FlexBOSS18 and FlexBOSS21 Indoor kits.

Key Features

  • 16 kWh nominal from one unit — 314Ah at 51.2V; EG4 lists 12.86 kWh usable at 80% depth of discharge
  • UL1973 | UL9540A | UL9540 with FlexBOSS21 and FlexBOSS18 — certifications exactly as EG4 publishes them
  • Self-heating cells — a 448W internal heater activates at or below 32°F per EG4, so a freezing garage does not take charging offline
  • 10,000+ cycles at 80% DoD per EG4, for up to 115.7 MWh of lifetime energy throughput
  • 157A max continuous charge / 200A max continuous discharge, with 12.8 kW 3-second peak per EG4
  • Hybrid wall or floor mount design keeps garage floor space usable
  • BMS with Wi-Fi monitoring through the EG4 Connect app and RS485/CAN closed-loop communication
  • Parallels up to 32 units per EG4 for large-capacity banks

Why EG4

EG4 Electronics is a Texas-based manufacturer that publishes complete spec sheets, manuals, and fire-safety test data, and backs this battery for 10 years or 10,000 cycles. Because EG4 builds both the batteries and the FlexBOSS inverters, the closed-loop pairing is engineered and documented by one company — including the UL9540 system configuration many building departments ask about.

Specifications

Model WM48314IN
Nominal voltage 51.2V (48V class)
Capacity 314Ah / 16 kWh nominal (12.86 kWh usable at 80% DoD, per EG4)
Chemistry LiFePO4 (lithium iron phosphate)
Cycle life 10,000 cycles at 0.5C, 77°F, 80% DoD, per EG4
Max continuous charge 157A
Max continuous discharge 200A
Peak power 12.8 kW for 3 seconds, per EG4
Enclosure rating IP20 — indoor installation
Charge temperature 32°F to 122°F
Discharge temperature -4°F to 131°F
Self-heating 448W internal heater; on at 32°F or below, off at 37°F, per EG4
Dimensions 34.1 x 18.1 x 9.6 in
Weight 293.2 lb
Mounting Wall-attached or floor mount, per EG4
Max units in parallel 32, per EG4
Communication RS485 / CAN closed-loop; Wi-Fi via EG4 Connect app
Certifications UL1973; UL9540A; UL9540 with FlexBOSS21 and FlexBOSS18, per EG4
Warranty 10 years or 10,000 cycles, per EG4
SKU FEWMT-48161-G1

All-Weather vs Indoor — Which WallMount?

Choose this Indoor model when the battery will live in a garage, basement, or utility room: you get the same 16 kWh and 10,000-cycle rating as the All-Weather version in a lighter enclosure, plus EG4's published UL9540 system pairing with FlexBOSS inverters. If the battery must mount outside or in a weather-exposed location, choose the IP67-rated WallMount 314Ah All-Weather instead. Both models are self-heating — the Indoor unit's heater matters in unheated garages, not just outdoors.

Inverter Compatibility

The WallMount 314Ah Indoor runs closed-loop over RS485/CAN with EG4 inverters, and per EG4 it forms a UL9540 system configuration with the EG4 FlexBOSS21 and EG4 FlexBOSS18 hybrid inverters. Closed-loop keeps the inverter's state-of-charge reading accurate and charge parameters coordinated. Running a different 48V inverter? Call us to confirm protocol support before ordering.

Installation

Installation should be performed by a licensed electrician, and residential energy storage is subject to local permitting and inspection. The unit weighs 293.2 lb and supports wall-attached or floor-mount installation per EG4 — wall mounting requires anchoring into structural framing rated for the load, and positioning takes lifting equipment or several people. Follow the EG4 installation manual for mounting hardware, torque values, and clearances, and confirm placement rules for energy storage with your local building department.

Warranty & Support

EG4 warrants this battery for 10 years or 10,000 cycles, whichever comes first. Register the battery with EG4 after purchase and keep your OffGrid Horizon invoice — as an authorized dealer, our sales records document your coverage. Need help with a claim or a firmware question? Call us at (302) 496-3554.

Shipping

This battery ships by LTL freight on a pallet within the United States. Delivery is curbside with a liftgate. Inspect the packaging and unit before signing the delivery receipt and note any damage with the driver — this preserves your ability to file a freight claim.

Frequently Asked Questions

Why does self-heating matter for an indoor battery?

LiFePO4 cells cannot accept charge below 32°F. Many "indoor" locations — detached garages, unheated basements, outbuildings — drop below freezing in winter. Per EG4, this pack's 448W heater switches on at 32°F and off at 37°F, keeping solar and grid charging available without an external heat source.

What does "UL9540 with FlexBOSS21 and FlexBOSS18" mean?

UL9540A is a fire-safety test method and UL1973 is the battery certification; UL9540 covers the complete energy storage system. Per EG4, this battery achieves the UL9540 system designation when paired with the FlexBOSS21 or FlexBOSS18 — useful documentation for permitting.

Can it be installed outdoors?

No — the enclosure is IP20 rated for indoor spaces. For outdoor mounting, use the WallMount 314Ah All-Weather.

How many can I parallel?

Up to 32 units per EG4's spec sheet, with capacity growing 16 kWh per battery.

How much power can one battery deliver?

200A continuous discharge — roughly 10.2 kW at nominal voltage — with a 12.8 kW 3-second peak per EG4. Parallel batteries to support larger loads.

Does it come as part of a complete system?

Yes — we offer this battery pre-paired with the FlexBOSS18 or FlexBOSS21 in our Indoor kits, configurable from 16 to 48 kWh.

Questions about permitting documentation or bank sizing? Call OffGrid Horizon at (302) 496-3554 — we are a family-owned authorized EG4 dealer and talk through these details every day.

Customers also bought