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Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2 Connector B
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Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2 Connector B

FE-HV-ECS-4100
£851.84 ex VAT £1,022.21 inc VAT

How many batteries do you need?

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Store Your SolarUse free power after dark
Long Cycle LifeThousands of charge cycles
Managed & ProtectedBuilt-in battery management system
Technical Specifications
Battery TypeLiFePO4 prismatic cell
Nominal Energy4.03 kWh
Depth of Discharge90 %
Battery Voltage48.6 - 65.7 V
Continuous Discharge Rate2875 W
IP RatingIP65
View Full Datasheet

Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2 Connector B

Fox ESS · ECS 4100 high voltage series

Fox ESS ECS4100 4.03kWh HV Battery (Slave) V2 Connector B

Fox ESS ECS 4100 high voltage series — 4.03 kWh a module, two to seven modules a stack, up to 28.21 kWh in one column.

Storage is worth having because it moves energy in time — solar generated at midday, or electricity bought on an overnight rate, spent in the evening. What decides whether it pays is the usable capacity, the charge rate and the cycle life, in that order.

Usable capacity
3.63 kWhWhat you can actually draw
Nominal capacity
4.03 kWhRated cell capacity
Architecture
Fox HV stackThe inverter side it belongs to
Voltage window
48.6 – 65.7 VWhere it operates
Chemistry
LiFePO4 prismatic cellCell type
Depth of discharge
90 %How much of it is usable
Warranty
5 yearsAs standard from Fox ESS; 12 years when the installation is registered
Important

Please read before ordering

This battery requires a MINIMUM of 2 modules to work (Master + Slave) for H1/KH1/H3 Smart and 3 modules for H3/H3 Pro inverters. This battery can have a MAXIMUM of 7 modules in a stack (1x Master + 6x Slaves)

If upgrading an existing system make sure it is a V2. ClearRay Solar have only received V2 of the 4100 battery model, and as such there should be no compatibility issues when installing new systems or expanding existing systems when the original batteries were purchased from ClearRay Solar.

Overview

About the Fox ESS ECS 4100 high voltage series

The ECS is the Energy Cube generation of Fox's high-voltage range: 4.03 kWh nominal a module, 3.63 kWh usable at a 90 % depth of discharge, and at least 6,000 cycles. Seven modules make 28.21 kWh.

It is a stack rather than a battery. One master module carries the battery management and the display; each slave adds capacity. Two modules is the minimum that will run, and the number your inverter accepts is in the table below.

IP65 for outdoor or indoor use, cooled by natural convection with no fans.

Scaling

What each stack size gives you

Two modules minimum, seven maximum:

Stack size
2 modules8.06 kWh nominal — 7.25 kWh usable
3 modules12.09 kWh nominal — 10.88 kWh usable
4 modules16.12 kWh nominal — 14.51 kWh usable
6 modules24.18 kWh nominal — 21.76 kWh usable
7 modules28.21 kWh nominal — 25.39 kWh usable
Inverter compatibility

Which inverter will run this battery?

This is a Fox ESS high-voltage stack: modules wired in series to a few hundred volts, with one master carrying the battery management and the rest of the stack reporting to it.

How many of this module each Fox inverter family takes, from Product Compatibility Fox ESS UK 2026, the module count range for this inverter family:

Modules per stack
H1 / AC12 to 7 modules
KH / KA2 to 7 modules
H3 / AC33 to 7 modules
H3 Pro3 to 14 modules
H3 Smart2 to 7 modules

Inverters we stock that will run it:

Fox H1 5.0kW Hybrid Inverter with EPS 1PH Gen 2H1 Gen 2, single phase, 5.0 kW — the most common single-phase pairing.
Fox 7kW K Series Single Phase Hybrid InverterK Series 7 kW single phase, for larger single-phase homes.
Fox H3 Smart 10.0KW 3ph Hybrid InverterH3 Smart 10 kW, three phase.
Fox high-voltage modules are not mixed: a stack is one type, one master and the matching slaves, and the module count must sit inside the range above for this inverter. A Fox low-voltage battery (LV52) will not work on any of these inverters, and a high-voltage stack will not work on a low-voltage one.
For the installer

Stack rules, cabling and what else the job needs

The details that decide whether this battery suits the system:

  • One master plus one to six slaves. Two modules minimum, seven maximum, 28.21 kWh at full stack.
  • 25 A recommended discharge, 50 A maximum charge and discharge, 65 A peak for 30 seconds.
  • Fox's compatibility matrix counts the modules an inverter will carry in total. Where that number is larger than the maximum stack on the datasheet, it is because the inverter takes more than one stack in parallel — the per-stack limit still applies to each one.
  • A stack is one module type throughout. Fox modules of different capacities are not mixed in a series string, and a Fox low-voltage battery will not work on a high-voltage inverter or the other way round.
  • 570 mm wide and 380 mm deep at any stack size. 570 × 350 to 950 × 380 mm for two to seven modules, 74.3 kg at two modules to 254.3 kg at seven.
  • Charge −10 °C to +55 °C, discharge −10 °C to +55 °C, storage −20 °C to +55 °C. Maximum altitude 2,000 m.
  • The minimum stack is two modules on H1, KH1 and H3 Smart, and three on H3 and H3 Pro, so the stack stays inside the inverter's battery voltage window.
Applications

Where this battery earns its place

The ECS 4100 high voltage series is specified most often for these jobs.

Fox high-voltage retrofitsOn the H1, KH, H3, H3 Smart and H3 Pro matrix.
Expanding an existing Energy CubeSame generation, same connector, same stack.
Systems that growAdd a slave at a time, up to seven modules.
Outdoor installationIP65 and no fans.
Time-of-use tariffs50 A charge, 90 % depth of discharge.
Tight plant rooms570 mm wide and 380 mm deep at any size.
Before you order

Things worth knowing about this listing

These notes come from us and from the manufacturer, and they are the ones that most often cause a problem after delivery:
  • Register the installation with Fox ESS to activate the 12-year product warranty. Without registration it is 5 years. The registration page is at fox-ess.com, and the warranty document on this listing has the full terms.
Technical specification

Fox ESS ECS4100 technical data

This product
Nominal capacity4.03 kWh
Usable capacity3.63 kWh
Modules in this productOne slave module, V2 connector B — it adds capacity to a stack that already has an ECM4100 master
Nominal voltage57.6 V
Operating voltage range48.6 – 65.7 V
Continuous charge / discharge current50 A
Peak power65 A for 30 s
Depth of discharge90 %
Common to the range
Cell chemistryLiFePO4 prismatic cell
Module nominal energy4.03 kWh
Module nominal voltage57.6 V
Recommended discharge current25 A
Maximum charge / discharge current50 A
Peak discharge current65 A for 30 s
Round trip efficiency>95 %
Cycle life≥6,000
CommunicationCAN / RS485
Modules per stack2 to 7 (one master plus one to six slaves)
Stack capacity at seven modules28.21 kWh
Stack dimensions (W × H × D)570 × 350 to 950 × 380 mm for two to seven modules
Stack weight74.3 kg at two modules to 254.3 kg at seven
InstallationOutdoor or indoor, floor standing on the Fox stand
Charge temperature range−10 °C to +55 °C
Discharge temperature range−10 °C to +55 °C
Storage temperature range−20 °C to +55 °C
CoolingNatural convection
Humidity0 – 100 %, non-condensing
Maximum altitude2,000 m
Ingress protectionIP65
DisplayOne LED on a slave, seven on a master
Compliance and warranty
CertificationIEC 62619, EN IEC 61000-6-1/2/3/4, UN 38.3
Warranty5 years as standard from Fox ESS; 12 years when the installation is registered
Specification sourceData Sheet Fox ECS4100, version 3.1, 9 December 2022
Goes with this

Ordered with this battery more often than anything else

A battery is one part of a storage system. These are the parts our customers add most often:

Fox ESS ECS4100 4.03kWh HV Battery (Master) V2 Connector BThe V2 connector B master module.
Frequently asked questions

Questions we get asked about this inverter

Is one module a battery?

No. A stack is one master plus at least one slave, so the smallest working system is two modules.

How many can I fit?

Seven in a stack, 28.21 kWh. How many your inverter will take is in the table on this page.

How much of it can I use?

3.63 kWh a module, at a 90 % depth of discharge.

Can I add these to an existing Fox stack?

Only to an ECS stack of the same module and the same connector type. Send us a photograph of the existing stack and we will confirm the part before you order.

Can it go outside?

Yes. IP65, outdoor or indoor, floor standing on the Fox stand.

ClearRay Solar

Documents, advice and trade pricing

Every datasheet, certificate, installation manual and warranty document we hold for this product is in the Documents tab below. See the rest of our battery range, our hybrid inverters and our solar panels, or email sales@clearraysolar.com if you would like us to check a battery and inverter pairing before you order.

IP65 RatedBuilt for UK weather conditions

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Documents & Certificates
CE Declaration of Conformity (Attestation of Conformity) ECS 2.9/4.1/4.3 CE Declaration of Conformity HV & ECS Batteries - EN Data Sheet FOX ECS 4100 DE Data Sheet FOX ECS 4100 EN
Shipping & Returns

Delivery times vary by region:

  • UK — 1-2 business days
  • Highlands & Islands — 1-2 business days

Returns accepted within 14 days of delivery for unused items in original packaging.