$2,087.05
Fox ECS 4.14kWh HV Battery Slave ECS4300—
$2,087.05
The Story
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 |
Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Details & Craftsmanship
Every detail has been carefully considered to bring you the perfect product.
Description
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 |
