Skip to content
Contact Us Price Match Guarantee FAQs Why Buy From Us About Us Customer Reviews Installer Program Build Your System
BigBattery ETHOS 3x Expansion Kit

BigBattery ETHOS 3x Expansion Kit
$4,040.00 - $4,040.00
$4,040.00
$4,040.00 - $4,040.00
$4,040.00
✓ Authorized BigBattery Dealer
✓ Lowest Price Match Guarantee
✓ FAST & FREE Shipping: In Stock Ready To Ship
✓ Questions? Talk to a BigBattery Expert: 1-303-876-7654

Login for Exclusive Member Pricing.
Not a member? Create a Free Account.

+15.36kWh · ETHOS Expansion

BigBattery ETHOS 3x Expansion Kit

This kit adds 3 more ETHOS modules — 15.36kWh total — to an existing ETHOS system, along with the rack base and cabling needed to wire them into your Control Box.

Every module is the same 51.2V, 100Ah/5.12kWh unit used across the ETHOS line, so the capacity you add here performs identically to what you already have installed.

BigBattery ETHOS 3x Expansion Kit
12-Year Warranty*
Lowest Price Guarantee
Authorized BigBattery Dealer
Free Shipping
0% APR Financing
Expert Support: (303) 876-7654

What This Kit Adds

Adds Full ETHOS Modules, Not Just Cabling

Each expansion kit ships complete ETHOS modules plus the rack base and cabling needed to connect them to your existing Control Box — not just the cables alone.

Same 100Ah / 5.12kWh Module as Your Existing Stack

Every ETHOS module is identical, so capacity added through this kit matches your existing bank's performance exactly rather than introducing a mismatched pack.

Includes Rack Base and Cabling

An ETHOS Rack Base plus the power and communication cables needed to physically connect the new modules into your system are included.

UL9540, UL9540A, UL1973 Listed

The same certifications as every other ETHOS module — no downgrade in listing status for expansion capacity.

IP65 / NEMA 4X Sealed Enclosures

Each added module is sealed against dust and water intrusion, matching your existing installation.

Stacks to 16 Modules Total Per Control Box

Your Control Box supports up to 16 modules total, so this kit is one step toward that ceiling, not the end of what you can add.

What's Included

What's included: BigBattery ETHOS 3x Expansion Kit

What You Get

  • 3 × BigBattery ETHOS 48V 5.12kWh Stackable Battery Modules
  • 1 × ETHOS Rack Base
  • 3 × Power connection cable
  • 1 × Communication cable
  • Documentation

Requires an existing ETHOS Control Box and at least one installed module.

Full Specifications

Modules Added 3 (15.36kWh total, 300Ah)
Module Voltage 51.2V per module
Module Capacity 100Ah / 5.12kWh per module
Battery Chemistry LiFePO4
Cycle Life 3,500–5,000 cycles (80% DoD, 0.5C)
Peak Discharge (per module) 300A for 5 seconds
Max Charge Current (per module) 200A
Ingress Protection IP65 / NEMA 4X
Communication CANBus / RS485
Max System Total Up to 16 modules per ETHOS Control Box
Certifications UL9540, UL9540A, UL1973, UN38.3

Authorized BigBattery Dealer

We sell genuine BigBattery products backed by BigBattery's own warranty.

Lowest Price Guarantee

Find it cheaper from another authorized dealer? Call (303) 876-7654 before you order.

Real Support, Not a Ticket Queue

Sizing a battery bank or system? Call (303) 876-7654 and talk to a person.

BigBattery ETHOS 3x Expansion Kit: Frequently Asked Questions

Does this work with my existing ETHOS Control Box?
Yes — every ETHOS module and expansion kit is built to the same spec, so this connects to any existing ETHOS Control Box up to its 16-module system limit. If you're not sure how many modules your current setup already has, call (303) 876-7654 before ordering.
Do I need a separate Control Box for this kit?
No — this kit is for adding capacity to a system that already has a Control Box installed. If you're starting from scratch, you'll need a Control Box plus at least 2 modules first.
What's included beyond the battery modules?
An ETHOS Rack Base and the power and communication cables needed to physically wire the new modules into your existing stack — this is a complete expansion, not just loose batteries.
Can I keep expanding after this kit?
Yes, up to a total of 16 modules per Control Box. This kit is one step toward that ceiling.
Do you offer financing or price matching?
Yes. We offer 0% APR financing options through Affirm at checkout, and our Lowest Price Guarantee applies — if you find this product cheaper at another authorized BigBattery dealer, call us at (303) 876-7654 before you order and we'll take care of it.
Renewable Outdoors LLC BBB Business Review