BigBattery NEXUS 15 kWh 48V LiFePO4 battery paired with EG4 12000XP V2 all-in-one inverter

Product Description

This kit pairs one BigBattery NEXUS 48V LiFePO4 battery — 280Ah, 14.3 kWh usable per BigBattery — with the EG4 12000XP V2 off-grid inverter: 12,000W of continuous split-phase 120/240V output, up to 24,000W of PV through two 35A MPPTs, and per EG4 enough starting muscle to bring up a 5-ton air conditioner without a soft start. It is an off-grid system — the inverter accepts generator and grid input for charging and bypass, per EG4, but the kit is not sold as a grid-interactive (sell-back) system.

Who This Is For

Full-size off-grid homes and properties with heavy simultaneous loads — well pump, HVAC, kitchen appliances, and shop tools at the same time — that want maximum inverter headroom while starting with a single battery cabinet. If your loads are cabin-scale, the EG4 6000XP version of this kit is the lighter match; if you cycle the bank heavily every day, see the 30–45 kWh version of this kit.

Key Features

  • 12,000W continuous split-phase 120/240V output, per EG4; surge rated 18,000W (5 seconds), per BigBattery's kit listing
  • Up to 24,000W of PV input through two 35A MPPTs, per EG4
  • Starts a 5-ton AC without a soft start, per EG4
  • Generator input up to 90A, grid input up to 100A, 100A bypass, per EG4
  • Parallels up to 16 inverters, per EG4
  • NEXUS battery: 280Ah, 14.3 kWh usable, 6,000+ cycle life, self-heating function, aerosol fire suppression, per BigBattery
  • Battery parallels up to 15 units (up to 214.5 kWh), per BigBattery

Why BigBattery

BigBattery is a US company building LiFePO4 energy storage for off-grid and home backup use. NEXUS batteries ship from Texas, carry a 12-Year Limited Warranty, and are backed by lifetime USA-based technical support, per BigBattery — here matched with EG4's high-output XP-series inverter. Browse our EG4 collection for the rest of the line.

What's In the Kit

Solar panels, racking, and array wiring are not included. BigBattery's kit listing does not itemize cables or accessories, so call us at (302) 496-3554 before ordering and we'll confirm exactly what ships with your configuration.

Specifications

Battery 1 × BigBattery NEXUS, 48V class (51.2V nominal), LiFePO4, 280Ah
Usable energy 14.3 kWh, per BigBattery
Battery max continuous discharge 140A (7.6 kW max continuous power), per BigBattery
Battery cycle life 6,000+ cycles, per BigBattery
Battery communications RS485 / RJ45 / CAN; compatible with all EG4 inverters, per BigBattery
Battery dimensions / weight 19.7 × 27.5 × 15.7 in; approx. 315 lb
Inverter EG4 12000XP V2 — 12,000W continuous, split-phase 120/240V, per EG4
Surge 18,000W (5 s), per BigBattery's kit listing
Solar input Up to 24,000W through two 35A MPPTs, per EG4
AC input / bypass Generator up to 90A; grid up to 100A; 100A bypass, per EG4
Inverter parallel capability Up to 16 units, per EG4
Battery warranty 12-Year Limited Warranty, per BigBattery
Inverter warranty 5 years, per BigBattery's kit listing (EG4 warranty terms apply)
Kit SKU K0154

Sizing Your Off-Grid Home

One honest number up front: a single NEXUS supports up to 140A — about 7.6 kW — of continuous discharge, per BigBattery. This one-battery kit will not sustain the inverter's full 12,000W continuously from battery alone; sustained whole-home draws call for two or three NEXUS units (two, adding BigBattery's per-unit figures, support about 15.2 kW). The single-battery configuration makes sense when big PV or generator input carries the daytime peaks and the battery's job is overnight essentials.

On energy, example assumptions — adjust to your household: refrigerator 1.5 kWh/day, freezer 1.0, lighting 1.0, well pump 1.5, electronics 1.5, laundry and kitchen 3.0. Around 9.5 kWh/day before air conditioning, so 14.3 kWh usable (per BigBattery) is one comfortable day of autonomy — and a signal that most full-size homes running this inverter end up at the 30–45 kWh version.

Installation

Setting the 315 lb battery cabinet and mounting the inverter are the straightforward parts. Wiring 12,000W of split-phase output into a main panel — interconnection, overcurrent protection, grounding, bonding — belongs to a licensed electrician working to the National Electrical Code (NEC) and local codes; most jurisdictions require a permit and inspection for energy storage. Place the battery in a dry space kept above freezing; BigBattery's published charge range starts at 32°F.

Warranty & Support

Battery: covered by BigBattery's 12-Year Limited Warranty — in BigBattery's words, “BigBattery, Inc. guarantees that its products will be free from defects in material and workmanship for a period of twelve (12) years.” No registration needed, per BigBattery. Inverter: 5-year manufacturer warranty, per BigBattery's kit listing; EG4's warranty terms apply, and EG4 asks that products be registered or accompanied by proof of purchase from an authorized distributor — keep your order confirmation.

BigBattery publishes a 30-Day Money Back Guarantee; per BigBattery, non-defective returns are refunded at purchase price minus a 20% restocking fee, excluding shipping. All returns require a Return Merchandise Authorization (RMA) before anything ships back — call OffGrid Horizon at (302) 496-3554 and we'll open the RMA or warranty claim. We're a family-owned authorized BigBattery partner, and BigBattery backs its batteries with lifetime USA-based technical support.

Shipping

This kit ships as palletized freight within the United States. Inspect the pallet before signing: note any damage on the delivery receipt and contact us promptly — that notation keeps a freight claim simple.

Frequently Asked Questions

Can one battery really feed a 12,000W inverter?

Not at full continuous output — the NEXUS supports about 7.6 kW continuous per BigBattery. This configuration fits homes whose sustained loads sit below that, with the inverter's headroom reserved for starting surges and daytime solar-carried peaks. For sustained heavy loads, start with the 2- or 3-battery version.

Is this a grid-tie system?

No — the 12000XP V2 is an off-grid inverter. Its grid and generator inputs are for charging and bypass, per EG4; it is not sold as a grid-interactive (sell-back) system.

Are solar panels included?

No. The inverter accepts up to 24,000W of PV per EG4; panels and racking are sized to your site and sold separately.

Will it start my air conditioner or well pump?

Per EG4, the 12000XP V2 can start a 5-ton AC without a soft start, with 18,000W of 5-second surge per BigBattery's listing. Bring us your nameplate figures and we'll confirm the whole load picture.

Can I add more storage later?

Yes — NEXUS batteries parallel up to 15 units, per BigBattery. The 2- and 3-battery versions of this kit are listed separately.

Do I need an electrician?

Yes — AC interconnection, grounding, and code compliance are work for a licensed electrician, and most jurisdictions require a permit and inspection.

Big inverter, one battery — right call or not? Call OffGrid Horizon at (302) 496-3554 and we'll walk the math with you. Family-owned, authorized BigBattery partner.

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