Home » Fox EQ4800 4.66kWh HV Battery Slave
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-EQS-4800
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Fox EQ4800 4.66kWh HV Battery Slave

Fox ESS
£1,470.00 Inc. VAT £1,225.00 Exc. VAT
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The Fox EQ4800 4.66 kWh High Voltage Battery Slave (FE-HV-EQS-4800 / EQS4800) is the expansion module for Fox EQ4800 high-voltage battery stacks, and the direct replacement for the EC4800 Slave. Each module adds 4.66 kWh of fully usable storage capacity at 100% depth of discharge — making the EQ4800 Slave more energy-dense than the 90% DoD ECS4300 series. A single stack supports up to 8 Slave modules alongside one EQM4800 Master, giving a total maximum of 41.93 kWh per stack. The EQS4800 is also backwards-compatible with existing EC4800 Master systems (maximum 7 modules total when mixing generations).

4.66 kWh
Per module
100% DoD
Fully usable
>95%
Round-trip efficiency
8 max
Slaves per stack
IP65
Indoor / outdoor
⚠ Installer Note — Must be installed by a qualified electrician or MCS-accredited installer. High-voltage DC battery system. Register the install on the Fox ESS portal for full warranty activation.
⚡ Important — Slave cannot operate alone — This module requires a Fox EQ4800 Master (FE-HV-EQM-4800) or compatible EC4800 Master to operate. Maximum 9 modules per stack with EQM4800 (41.93 kWh); maximum 7 modules when mixed with EC4800 generation. EQ4800 Slaves are also compatible with existing EC4800 Master stacks.
Features & Benefits
✔ 100% DoD — No Wasted Capacity
Every kWh of nominal capacity is usable. At 100% depth of discharge, the EQ4800 Slave delivers the full 4.66 kWh per module — compared to approximately 3.73 kWh from a 4.14 kWh ECS4300 module at 90% DoD. This means fewer modules are needed for a given usable capacity target.
✔ Upgrade Path for EC4800 Systems
EQS4800 Slaves are backwards-compatible with existing EC4800 Master (ECM4800) stacks — if you need to expand an existing system and ECS4800 Slaves are unavailable, EQS4800 modules can be added directly. Mixed stacks are limited to 7 modules total.
✔ Scalable Post-Installation
Add Slave modules at any time without disrupting the existing system — up to a maximum of 8 Slaves per EQM4800 Master (41.93 kWh total). The plug-and-play buckle-fix design makes on-site expansion straightforward.
✔ LFP — Safest Lithium Chemistry
LiFePO₄ cells have no thermal runaway risk and ≥6,000 cycle life — over 16 years of daily cycling. Superior safety and longevity versus NMC-based battery systems commonly used in lower-cost alternatives.
✔ High Efficiency, High Voltage
High-voltage DC architecture reduces current and resistive losses through cabling, achieving >95% round-trip efficiency — more of what is stored actually comes back out as usable electricity.
✔ IP65 for Flexible Siting
IP65-rated for both indoor and outdoor installation (stand-mounted). Natural convection cooling — no fans, no noise, no moving parts. Suitable for garages, utility rooms, and sheltered outdoor locations.
Technical Specifications
Part Number (Slave) FE-HV-EQS-4800 / EQS4800
Module Type Slave (requires EQM4800 or ECM4800 Master)
Battery Chemistry LFP (LiFePO₄)
Nominal Energy per Module 4.66 kWh
Depth of Discharge 100%
Round-Trip Efficiency >95%
Cycle Life ≥6,000 cycles
Normal Capacity 104 Ah
Recommended Charge/Discharge Current 30 A
Max Charge/Discharge Current 50 A
Peak Discharge Current (60 s) 65 A
Communication CAN (daisy-chain via Master)
Max Slaves per Stack (EQM4800) 8 (max stack: 41.93 kWh)
Max Modules (mixed EC4800 stack) 7 total
Operating Temperature — Discharge –10°C to +55°C
Operating Temperature — Charge 0°C to +55°C
Ingress Protection IP65
Certifications IEC 62619, EN IEC 61000-6-1/2/3/4, UN38.3
Warranty 10×3 years (see Fox ESS Battery Warranty Terms)
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

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