The BigBattery ETHOS Builds a UL 9540 Home Battery System From Stackable 5.12kWh Modules That Grows From 10kWh to Over 40kWh
The BigBattery ETHOS is a 48V lithium iron phosphate home battery made of stackable 5.12kWh modules. Two or more modules stack on a rack base under the ETHOS Control Box, which links them to your inverter and shows system status on its front display. Because each module is IP65 and NEMA 4X rated, an ETHOS stack can go in a garage, a utility room or outdoors against the house.
Choose a single module to expand an ETHOS system you already own, or a complete system of 2, 3, 4, 6 or 8 modules (10.24kWh to 40.96kWh) that includes the Control Box and the cables to connect it. ETHOS is certified to UL9540, UL9540A and UL1973, which makes it one of the few modular batteries that can be used in permitted grid-tied installations with the right inverter.
BigBattery backs ETHOS with a 12-year warranty and lifetime USA-based technical support, and it ships from Texas.
BigBattery ETHOS 48V Battery Features
Modular 5.12kWh Building Blocks
Each module stores 5.12kWh at 51.2V nominal (100Ah). Stack two for 10.24kWh, three for 15.36kWh, or set up two side-by-side stacks for 20.48kWh to 40.96kWh. Up to 16 modules run on one control box, for more than 80kWh.
Control Box With Front Display
The ETHOS Control Box sits on top of the stack and handles inverter communication over CANBus or RS485. Its LED interface shows system voltage, remaining capacity, BMS status codes and inverter communication settings.
UL 9540 Certified System
ETHOS carries UL9540, UL9540A, UL1973 and UN38.3 certifications. For grid-tied installs, closed-loop operation is certified with the EG4 18kPV, FlexBOSS18 and FlexBOSS21 hybrid inverters, which helps with permitting and inspections.
High Output for Whole-Home Loads
A 2-module stack delivers 200A continuously (10.24kW). Stacks of three or more modules deliver 250A (12.8kW) continuously, with a 300A peak for up to 5 seconds and up to 200A of charge current.
Indoor or Outdoor Installation
The IP65 / NEMA 4X rating protects against dust and water jets, and modules discharge from -4°F to 140°F. Charging is allowed from 32°F to 113°F.
Safe LiFePO4 Chemistry
Each module has a smart BMS with automatic cell balancing and internal fire suppression. BigBattery rates ETHOS for 6,000+ cycles, well over a decade of daily cycling.
Plug-In Connections
Modules connect with Amphenol ESS connectors and the included cables, so adding capacity means stacking another module and plugging it in rather than rewiring the system.
Real-World Applications
Whole-home backup. Keep refrigerators, well pumps, HVAC blowers, lights and internet running during grid outages. BigBattery suggests four to six modules for whole-house backup with air conditioning or electric heat.
Grid-tied solar with storage. Pair ETHOS with an EG4 18kPV, FlexBOSS18 or FlexBOSS21 to store daytime solar and use it in the evening or during peak rate periods.
Off-grid homes. Run ETHOS with a BigBattery APEX or EG4 off-grid inverter for full-time solar living.
Growing systems. Start with two modules and add more later with ETHOS expansion kits.
How It Compares to Common Alternatives
Versus lead-acid battery banks. LiFePO4 delivers far more usable capacity per pound, needs no watering or equalizing, and lasts thousands more cycles.
Versus single-cabinet home batteries. Fixed-size batteries make you choose capacity up front. ETHOS lets you add 5.12kWh at a time as your needs change.
Versus rack-mount server batteries. Server rack batteries usually need an indoor cabinet and separate bus bars. ETHOS stacks on its own rack base, is rated for outdoor use and carries UL 9540 certification as a system.
Is This ETHOS System the Right Fit
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System voltage. 48V nominal inverters.
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Inverter. UL 9540 grid-tied systems with closed-loop communication are certified with the EG4 18kPV, EG4 FlexBOSS18 and EG4 FlexBOSS21. For off-grid installations that do not require UL 9540, ETHOS communicates with all BigBattery APEX inverters and all EG4 inverters.
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Minimum system. At least two modules plus the ETHOS Control Box. A single module is for expanding an existing ETHOS system.
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Space. A 2-module stack is 26.5 in wide, 6.7 in deep and 43.3 in high. A 3-module stack is 59.8 in high, and 4- and 6-module systems use two stacks side by side (53.1 in wide).
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Weight. About 121 lbs per module.
This may be a good fit if
- You want a UL 9540 certified battery for a permitted grid-tied install
- You want to start small and add capacity later
- Your batteries need to go in a garage or outdoors
- You run an EG4 or BigBattery APEX inverter
Common Questions
Can I Add More ETHOS Batteries Later?
Yes. ETHOS is modular, so you can start with two modules and add more with single modules or 2x and 3x expansion kits, up to 16 modules on one control box.
How Many Modules Do I Need?
Each module is 5.12kWh. BigBattery says two modules cover essential circuits through a typical outage, and whole-house backup with air conditioning or electric heat usually takes four to six. Start from your daily kWh use and the number of outage days you want to cover.
Does a Single Module Work on Its Own?
No. The 1 x ETHOS option is a single module for expanding an existing ETHOS stack. A working system needs at least two modules and the ETHOS Control Box, which are included in the 2x and larger options.
Which Inverters Work With ETHOS?
UL 9540 grid-tied systems with closed-loop communication are certified with the EG4 18kPV, EG4 FlexBOSS18 and EG4 FlexBOSS21. For off-grid installations that do not require UL 9540, ETHOS communicates with all BigBattery APEX inverters and all EG4 inverters.
Can I Mix ETHOS Modules With Other Batteries?
ETHOS modules connect in parallel with other ETHOS modules only, and they are not designed for series connection. BigBattery recommends that all modules be within 0.3V of each other before connecting.
How Long Does ETHOS Last?
BigBattery rates it for 6,000+ cycles and backs it with a 12-year warranty. At the end of its life, BigBattery will recycle it free of charge.
What's Included
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1 x ETHOS Battery (5.12kWh): 1 x BigBattery ETHOS 48V 5.12kWh battery module with battery comm cable, battery-to-battery power cables, and L mounting brackets with screws (expansion module, no control box)
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2 x ETHOS Batteries (10.24kWh): 2 x ETHOS battery modules, 1 x ETHOS Control Box, 1 x 10kWh ETHOS Controller to Battery Power Cable (31.5 in)
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3 x ETHOS Batteries (15.36kWh): 3 x ETHOS battery modules, 1 x ETHOS Control Box, 1 x 15kWh ETHOS Controller to Battery Power Cable (4 ft)
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4 x ETHOS Batteries (20.48kWh): 4 x ETHOS battery modules, 1 x ETHOS Control Box, 1 x ETHOS Rack Base, 1 x ETHOS Stack to Stack Power Cable Pair (4.9 ft), 1 x ETHOS Stack to Stack Comm Cable (4.9 ft)
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6 x ETHOS Batteries (30.72kWh): 6 x ETHOS battery modules, 1 x ETHOS Control Box, 1 x ETHOS Rack Base, 1 x ETHOS Stack to Stack Power Cable Pair (4.9 ft), 1 x ETHOS Stack to Stack Comm Cable (4.9 ft)
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8 x ETHOS Batteries (40.96kWh): 8 x ETHOS battery modules, 1 x ETHOS Control Box, 2 x ETHOS Rack Base, 2 x ETHOS Stack to Stack Power Cable Pair (4.9 ft), 4 x ETHOS Stack to Stack Comm Cable (4.9 ft)
Home Storage That Grows With You
The BigBattery ETHOS gives you UL 9540 certified LiFePO4 storage in 5.12kWh steps, from a 10kWh starter system to more than 40kWh. At Outbound Power, we help customers choose the right parts for their solar and battery systems. If you have questions, our team is happy to help.
BigBattery ETHOS Home Lithium Battery Specifications
|
| Single Module (FETHS-48051-G1) |
| Capacity |
5.12kWh, 100Ah |
| Cell Configuration |
16S |
| Max Continuous Discharge |
100A (5,120W) |
| Dimensions (D x W x H) |
6.7 x 26.5 x 16.14 in (170 x 674 x 410 mm) |
| Weight |
121 lbs (54.8 kg) |
| System Configurations |
| 2 Modules (K0948) |
10.24kWh, 200Ah, 16S2P, 200A / 10,240W continuous, 43.3 in high, 273 lbs |
| 3 Modules (K0950) |
15.36kWh, 300Ah, 16S3P, 250A / 12,800W continuous, 59.8 in high, 387 lbs |
| 4 Modules (K0951) |
20.48kWh, 400Ah, 16S4P, 250A / 12,800W continuous, 53.1 in wide x 43.3 in high, 513 lbs |
| 6 Modules (K0953) |
30.72kWh, 600Ah, 16S6P, 250A / 12,800W continuous, 53.1 in wide x 59.8 in high, 755 lbs |
| 8 Modules (K0150) |
40.96kWh, 800Ah |
| GTIN-12 (UPC) |
850061252005 |
| Common Specifications |
| Nominal Voltage |
51.2V (48V system) |
| Chemistry |
LiFePO4 |
| Charging Voltage Range |
55.6V to 57V |
| Max Charge Voltage |
57V |
| Operating Voltage Range |
48V to 57V |
| Suggested Low Voltage Cutoff |
48V to 50.8V |
| BMS Cutoff Range |
42V to 47V |
| Max Discharge Peak Current |
300A (max 5 seconds) |
| Max Charge Current |
200A |
| Charge Temperature Range |
32°F to 113°F (0°C to 45°C) |
| Discharge Temperature Range |
-4°F to 140°F (-20°C to 60°C) |
| Optimal Discharge Temperature |
59°F to 95°F (15°C to 35°C) |
| Storage Temperature (SoC above 50%) |
-4°F to 113°F (-20°C to 45°C), max 6 months |
| Max Connections |
Up to 16 modules per control box |
| Communications |
CANBus, RS485 |
| Protection Rating |
IP65 / NEMA 4X |
| Certifications |
UL9540, UL9540A, UL1973, UN38.3 |
| Cycle Life |
6,000+ cycles |
| Warranty |
12 years |
BigBattery ETHOS 48V Battery Manual & Downloads
BigBattery ETHOS 48V Battery Spec Sheet
BigBattery ETHOS 48V Battery Manual
UL9540A Certificate
UL1973 Certificate
UN38.3 Certificate
Safety Data Sheet
