Product Summary:

The BigBattery ETHOS™ + EG4 FlexBOSS18 ESS System is a complete, high-performance energy solution designed for both on-grid and off-grid applications. Combining the scalable ETHOS 48V lithium battery system with the powerful FlexBOSS18 hybrid inverter, this system delivers reliable, efficient, and intelligent energy management in one integrated package.

 

Expandable up to 80+ kWh, the ETHOS battery adapts to your energy needs – while the FlexBOSS18 provides up to 18,000W PV input, dual MPPTs, and 120/240V split-phase output for flexible system design and strong performance. Integrated with the GridBOSS MID gateway, the system enables advanced energy control, including load management, AC coupling, and generator integration.

 

Designed with UL 9540 certified configurations, advanced battery management, and U.S.-engineered components, this system ensures safe, maintenance-free performance with seamless closed-loop communication and real-time monitoring.

Ships From: Texas, USA
Warranty: 12 Years (Battery), 10 Years (Inverter)
Support: Lifetime USA-Based Tech Support

 

Compatibility

Integrated & Optimized System:

  • ETHOS Battery System + EG4 FlexBOSS18 Hybrid Inverter

Expandable & Flexible:

  • Scalable ETHOS battery capacity up to 80+ kWh
  • Compatible with additional ETHOS modules for future expansion
  • Supports grid-tied, hybrid, and off-grid installations
Key Features
  • Complete ESS Solution – Battery + inverter system designed to work seamlessly together
  • 18,000W PV Input – High solar capacity with dual MPPT optimization
  • 120/240V Split-Phase Output – Powers residential and light commercial loads
  • LiFePO₄ Battery Chemistry – Safe, stable lithium technology with long lifespan
  • 6,000+ Cycle Life – Built for years of daily use and long-term savings
  • Closed-Loop Communication – Optimized coordination between battery and inverter
  • GridBOSS Integration – Advanced load management, AC coupling, and generator support
  • Advanced Safety Protections – Includes rapid shutdown, ground fault, and arc fault protection
  • Modular Expansion – Easily scale storage capacity as energy needs grow
  • Remote Monitoring & Alerts – Wi-Fi connectivity with real-time system tracking
  • Maintenance-Free Operation – No routine servicing required

A complete, scalable energy storage system built for performance, flexibility, and long-term independence – backed by safety, smart controls, and U.S.-based support.

Battery Downloads

SKU#:K0230, K0231, K0232, K0233, K0234, K0235, K0236, K0237, K0238, K0239, K0240
Spec Sheet:DownloadDOWNLOAD
User Manual:DownloadDOWNLOAD
UL9540 Certificate – BigBattery ETHOS + EG4 FlexBOSS18:DownloadDOWNLOAD
UL9540A Certificate:DownloadDOWNLOAD
UL1973 Certificate:DownloadDOWNLOAD
UN38.3 Certificate:DownloadDOWNLOAD
Safety Data Sheet:DownloadDOWNLOAD
CEC Listing – BigBattery ETHOS + EG4 FlexBOSS18:Go to linkGO TO LINK

Battery Specifications

GTIN-12 (U.P.C.):850061252005
System Voltage:48V
Nominal Voltage:51.2V
Chemistry:LiFePO4
kWh Capacity:10.24kWh
Ah Capacity:200Ah
Charging Voltage Range:55.6 – 57V
Max Charge Voltage:57V
Operating Voltage Range:48 – 57V
Suggested Low Voltage Cutoff:48 – 50.8V
BMS Cutoff Range:42 – 47V
Cell Configuration:16S 2P
Max Continuous Discharge Current:200A
Max Continuous Power:10240W
Max Discharge Peak Current:300A (Max 5 seconds)
Max Charge Current:200A
Charge Temperature Range:32°F – 113°F (0°C – 45°C)
Discharge Temperature Range:-4°F – 140°F (-20°C – 60°C)
Optimal Discharge Temperature Range:59°F – 95°F (15°C – 35°C)
Storage Temperature Range (SoC >50%):-4°F – 113°F (-20°C – 45°C)(Max 6 months)
Weight:273 lb (123.8 kg)
Depth:6.7 in (170 mm)
Width:26.5 in (674 mm)
Height:43.3 in (1100 mm)
Max Connections:Up to (16) parallel connections per control box
Protection Rating:IP65 / NEMA 4X
Communications:CANBus / RS485
Certifications:UL9540, UL9540A, UL1973, & UN38.3

Inverter Downloads

SKU#:K0230, K0231, K0232, K0233, K0234, K0235, K0236, K0237, K0238, K0239, K0240
Spec Sheet:DownloadDOWNLOAD
User Manual:DownloadDOWNLOAD
UL1741 Certificate:DownloadDOWNLOAD
CEC Listing – BigBattery ETHOS + EG4 FlexBOSS18:Go to linkGO TO LINK

Inverter Specifications

Nominal AC Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Frequency:60 Hz (Default) | 50 Hz
Max. AC Current:54A @ 240V | 54A @ 208V
Max. AC Input Power:13000W
Max. AC Bypass:90A
Operating Voltage Range:180 – 270VAC
Output Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Max. Output Current:66.7A
Output Frequency:60 Hz (Default) | 50 Hz
Nominal Output Power (without PV):12000W @ 240V | 12000W @ 208V
Nominal Output Power (with PV):16000W @ 240V | 13800kW @ 208V
Power Factor:0.99 (Full Load)
Reactive Power Adjustment Range:-0.8 – 0.8 Leading Adjustable
Total Harmonic Distortion:<5% (Full Load)
Transfer Time:20ms (Default) | 10ms (Configurable) | 20ms (Parallel)
Rated Output Current:50A @ 240V | 57.7A @ 208V
Nominal Output Voltage:120/240VAC | 120/208VAC
Rated Output Power:12000W @ 240VAC | 12000W @ 208VAC
Peak Power:20000W (0.5 sec) | 15000W (1 sec)
12500W (6 min) | 11000W (12 min)
Operating Frequency:60 Hz (Default) | 50 Hz
Total Harmonic Distortion Voltage:<5%
No. of MPPTs:2
Inputs per MPPT:2 (MPPT 1) | 2 (MPPT 2)
Max. Usable Input Current:26A (MPPT 1) | 26A (MPPT 2)
Max. Short Circuit Input Current:31A (MPPT 1) | 31A (MPPT 2)
DC Input Voltage Range:100 – 600VDC
Unit Start-Up Voltage:200VDC
MPPT Operating Voltage Range:120 – 440VDC
Nominal MPPT Voltage:360VDC
Max. Utilized PV Array Power:1818000W
Max. Recommended PV Input:18000W
Max. Efficiency:97.5% (PV to Grid) | 94.5% (PV to Battery) | 94% (Battery to Grid)
Idle Consumption:<65W
Nominal Voltage:48VDC
Voltage Range:40 – 60VDC
Max. Charge / Discharge Power:10000W
Recommended Battery Capacity per Inverter:>300Ah
Operating / Storage Temperature Range:-13ºF – 140ºF (-25ºC – 60ºC)
Operating Altitude:<6,561 ft (2000 m)
Relative Humidity:0 – 100%
Typical Noise Emission:<50dB @ 3 ft
Design Topology:High-Frequency / Transformerless
Protection Rating:IP65 / NEMA 4X
Communications:RS485 / CANBus / WiFi / 4G
Max. Parallel Connections:10
Weight:115 lbs (52 kg)
Depth:11.2 in (287 mm)
Width:22.8 in (567 mm)
Height:30.5 in (775 mm)

Battery Downloads

SKU#:K0230, K0231, K0232, K0233, K0234, K0235, K0236, K0237, K0238, K0239, K0240
Spec Sheet:DownloadDOWNLOAD
User Manual:DownloadDOWNLOAD
UL9540 Certificate – BigBattery ETHOS + EG4 FlexBOSS18:DownloadDOWNLOAD
UL9540A Certificate:DownloadDOWNLOAD
UL1973 Certificate:DownloadDOWNLOAD
UN38.3 Certificate:DownloadDOWNLOAD
Safety Data Sheet:DownloadDOWNLOAD
CEC Listing – BigBattery ETHOS + EG4 FlexBOSS18:Go to linkGO TO LINK

Battery Specifications

GTIN-12 (U.P.C.):850061252005
System Voltage:48V
Nominal Voltage:51.2V
Chemistry:LiFePO4
kWh Capacity:10.24kWh
Ah Capacity:200Ah
Charging Voltage Range:55.6 – 57V
Max Charge Voltage:57V
Operating Voltage Range:48 – 57V
Suggested Low Voltage Cutoff:48 – 50.8V
BMS Cutoff Range:42 – 47V
Cell Configuration:16S 2P
Max Continuous Discharge Current:200A
Max Continuous Power:10240W
Max Discharge Peak Current:300A (Max 5 seconds)
Max Charge Current:200A
Charge Temperature Range:32°F – 113°F (0°C – 45°C)
Discharge Temperature Range:-4°F – 140°F (-20°C – 60°C)
Optimal Discharge Temperature Range:59°F – 95°F (15°C – 35°C)
Storage Temperature Range (SoC >50%):-4°F – 113°F (-20°C – 45°C)(Max 6 months)
Weight:273 lb (123.8 kg)
Depth:6.7 in (170 mm)
Width:26.5 in (674 mm)
Height:43.3 in (1100 mm)
Max Connections:Up to (16) parallel connections per control box
Protection Rating:IP65 / NEMA 4X
Communications:CANBus / RS485
Certifications:UL9540, UL9540A, UL1973, & UN38.3

Inverter Downloads

SKU#:K0230, K0231, K0232, K0233, K0234, K0235, K0236, K0237, K0238, K0239, K0240
Spec Sheet:DownloadDOWNLOAD
User Manual:DownloadDOWNLOAD
UL1741 Certificate:DownloadDOWNLOAD
CEC Listing – BigBattery ETHOS + EG4 FlexBOSS18:Go to linkGO TO LINK

Inverter Specifications

Nominal AC Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Frequency:60 Hz (Default) | 50 Hz
Max. AC Current:54A @ 240V | 54A @ 208V
Max. AC Input Power:13000W
Max. AC Bypass:90A
Operating Voltage Range:180 – 270VAC
Output Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Max. Output Current:66.7A
Output Frequency:60 Hz (Default) | 50 Hz
Nominal Output Power (without PV):12000W @ 240V | 12000W @ 208V
Nominal Output Power (with PV):16000W @ 240V | 13800kW @ 208V
Power Factor:0.99 (Full Load)
Reactive Power Adjustment Range:-0.8 – 0.8 Leading Adjustable
Total Harmonic Distortion:<5% (Full Load)
Transfer Time:20ms (Default) | 10ms (Configurable) | 20ms (Parallel)
Rated Output Current:50A @ 240V | 57.7A @ 208V
Nominal Output Voltage:120/240VAC | 120/208VAC
Rated Output Power:12000W @ 240VAC | 12000W @ 208VAC
Peak Power:20000W (0.5 sec) | 15000W (1 sec)
12500W (6 min) | 11000W (12 min)
Operating Frequency:60 Hz (Default) | 50 Hz
Total Harmonic Distortion Voltage:<5%
No. of MPPTs:2
Inputs per MPPT:2 (MPPT 1) | 2 (MPPT 2)
Max. Usable Input Current:26A (MPPT 1) | 26A (MPPT 2)
Max. Short Circuit Input Current:31A (MPPT 1) | 31A (MPPT 2)
DC Input Voltage Range:100 – 600VDC
Unit Start-Up Voltage:200VDC
MPPT Operating Voltage Range:120 – 440VDC
Nominal MPPT Voltage:360VDC
Max. Utilized PV Array Power:1818000W
Max. Recommended PV Input:18000W
Max. Efficiency:97.5% (PV to Grid) | 94.5% (PV to Battery) | 94% (Battery to Grid)
Idle Consumption:<65W
Nominal Voltage:48VDC
Voltage Range:40 – 60VDC
Max. Charge / Discharge Power:10000W
Recommended Battery Capacity per Inverter:>300Ah
Operating / Storage Temperature Range:-13ºF – 140ºF (-25ºC – 60ºC)
Operating Altitude:<6,561 ft (2000 m)
Relative Humidity:0 – 100%
Typical Noise Emission:<50dB @ 3 ft
Design Topology:High-Frequency / Transformerless
Protection Rating:IP65 / NEMA 4X
Communications:RS485 / CANBus / WiFi / 4G
Max. Parallel Connections:10
Weight:115 lbs (52 kg)
Depth:11.2 in (287 mm)
Width:22.8 in (567 mm)
Height:30.5 in (775 mm)
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