Home » Fox ECS 4.14kWh HV Battery Slave ECS4300
Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2
Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2
Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2
Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2
SKU: FE-HV-ECS-4300
(0)

Fox ECS 4.14kWh HV Battery Slave ECS4300

Fox ESS
£1,370.00 Inc. VAT £1,141.67 Exc. VAT
Free Shipping

Free shipping on solar panels for orders above £2,500!

  • FREE Express Delivery (1-3 days) in UK Mainland on most orders
  • Excluding: Solar Panels (£170 delivery / free above £2,500), Batteries (£49 delivery), Small Items (£4.95 delivery / free above £500)
  • Contact Us to check for Next Working Day Delivery or Same-day Delivery options
  • Contact Us for Click & Collect options
  • Custom quote available on request
*See checkout or shipping policy for full details

Payment options

  • American Express
  • Apple Pay
  • Bancontact
  • Diners Club
  • Discover
  • Google Pay
  • Klarna
  • Maestro
  • Mastercard
  • PayPal
  • Shop Pay
  • Union Pay
  • Visa

Documentation

Downloads

Do you have a question
about this product?

One of our expert advisors will be happy to help you!

Contact Us
Question Image

The Fox ECS 4.14 kWh High Voltage Battery Slave (FE-HV-ECS-4300 / ECS4300) is an expansion module for an existing Fox ECS high-voltage battery stack. Each Slave adds 4.14 kWh of storage capacity to a stack managed by one ECS Master module (ECM4300). A stack can hold up to six Slave modules alongside one Master, giving a maximum capacity of 29.03 kWh in a single stack. Slave modules use the same LFP (LiFePO₄) chemistry and IP65-rated enclosure as the Master and share identical electrical performance — 90% DoD, >95% round-trip efficiency, and ≥6,000 cycle life.

4.14 kWh
Per module
90% DoD
Usable energy
>95%
Round-trip efficiency
29.03 kWh
Max stack capacity
IP65
Outdoor rated
⚠ Installer Note — Must be installed by a qualified electrician or MCS-accredited installer. High-voltage DC battery system. Register the install with Fox ESS to activate the extended 12-year warranty.
⚡ Important — Slave cannot operate alone — This module requires a Fox ECS Master (FE-HV-ECM-4300) to function. A new installation needs at minimum 1× Master + 1× Slave. If expanding an existing stack, confirm compatibility with your current modules before ordering — consult the Fox ESS technical portal with a photo of the existing stack.
Features & Benefits
✔ Scalable Capacity Expansion
Add Slave modules at any time — before or after the original installation — up to a maximum of 6 Slaves per Master stack. Each Slave adds exactly 4.14 kWh, allowing precise capacity planning in 4.14 kWh increments.
✔ Identical Performance to Master
The Slave module shares the same LFP cell specification as the Master — 90% DoD, >95% round-trip efficiency, and ≥6,000 cycle life — ensuring consistent whole-stack performance as capacity is expanded.
✔ Simple Buckle-Fix Connections
Modules stack vertically with a mechanical buckle-fix system and a single CAN communication daisy-chain — no complex wiring or reconfiguration of the inverter is required when adding modules post-install.
✔ LFP Safety & Longevity
LiFePO₄ chemistry provides inherently stable electrochemistry with no thermal runaway risk — the safest lithium battery technology for residential installations. Rated for over 16 years of daily cycling at 90% DoD.
✔ IP65 — Indoor or Outdoor
IP65 dust and water-jet protection allows installation in garages, plant rooms, or sheltered outdoor locations. Natural convection cooling — no fans, no noise, no maintenance.
✔ Wide Operating Temperature
Discharges reliably from –10°C to +55°C, making it suitable for year-round use in unheated UK garages and outbuildings. Charge derating applies between 0°C and +15°C to protect cell longevity.
Technical Specifications
Part Number (Slave) FE-HV-ECS-4300 / ECS4300
Module Type Slave (requires Master FE-HV-ECM-4300)
Battery Chemistry LFP (LiFePO₄) Prismatic Cell
Nominal Energy per Module 4.14 kWh
Depth of Discharge 90%
Round-Trip Efficiency >95%
Cycle Life ≥6,000 cycles @ 90% DoD, 0.5C
Max Charge/Discharge Current 50 A
Peak Discharge Current (30 s) 65 A
Communication CAN (daisy-chain via Master)
Max Slaves per Stack 6 (max stack: 1 Master + 6 Slaves = 29.03 kWh)
Operating Temperature — Discharge –10°C to +55°C
Operating Temperature — Charge 0°C to +55°C (derating 0–15°C)
Ingress Protection IP65
Certifications IEC 62619, IEC 61000-6-1/2/3/4, UN38.3
Warranty 5 years standard; 12 years with online registration
BTU & WATT Calculator
Room Dimensions
Room Type
Living Room
Bedroom
Kitchen
Bathroom
Conservatory
Hallway
Glazing Type
Single Glazed
Double Glazed
Triple Glazed
External Walls
0 Wall
1 Wall
2 Walls
3 Walls
4 Walls
Insulation Level
Poor
Average
Good (New Build)
Required Heating
0
Watts
0
BTUs

Get in touch with our team and receive a custom quote for your project
Request a custom quote