Fox ESS 4.32kWh Battery Slave Module | EQ4300-S | Replaces CS4300H

Description

The Fox ESS EQ4300-S Slave module adds 4.32kWh of LiFePO₄ storage to an EQ4300 stack. It is a battery-only expansion module that connects to the stack Master, so you can start small and scale up to 30.24kWh with up to 6 Slaves per Master. It is the current replacement for the CS4300H slave module and is compatible with ECS4300H systems, so owners of older Fox ESS stacks can still add capacity.

Each module is a floor-standing, plug-and-play unit with 90% depth of discharge, round-trip efficiency above 95% and a cycle life of 6000 cycles or more. Rated IP65 for outdoor or indoor installation with natural convection cooling, it is built to be stacked in minutes.

4.32kWh

Per Slave module

Up to 6

Slaves per Master

90%

Depth of discharge

≥6000

Cycle life

>95%

Round-trip efficiency

IP65

Outdoor / indoor

A Slave needs an EQ4300-M Master

The Slave has no stack controller of its own and cannot run without a Master. A system is 1 Master + 1 to 6 Slaves, and H3 Pro stacks need at least 2 Slaves per Master.

Replaces the CS4300H and extends ECS4300H systems

The EQ4300-S is the replacement for the CS4300H slave module and the EQ4300 range has superseded the ECS4300H range. Use it to add capacity to an existing ECS4300H stack with your original CM4300H master in place.

Mixing with older ECS modules

Fox ESS advises checking compatibility with your original modules before ordering, for example by confirming the model on your existing stack. In a mixed ECS and EQ stack the battery warm-up function is disabled.

Key features

Simple capacity expansion

Add 4.32kWh per module and grow your stack to a maximum of 30.24kWh (1 Master + 6 Slaves).

Plug-and-play installation

Plug-and-play connections and a modular, stackable design save valuable time for installers.

90% depth of discharge

Access 90% of rated capacity with pack round-trip efficiency above 95%.

LiFePO₄ long life

Prismatic LiFePO₄ cells rated at 6000 cycles or more (25°C, 90% DoD, 0.5C).

IP65, wide temperature range

IP65 enclosure for outdoor or indoor use, charging from 0 ~ 55°C and discharging from -10 ~ 55°C.

Backwards compatible

Replaces the CS4300H and extends ECS4300H stacks, subject to a compatibility check with your original modules.

Recommended Fox ESS inverters

EQ4300 Slaves work as part of a stack that is controlled by an EQ4300-M Master and connected to a Fox ESS hybrid inverter:

Fox ESS H1-G2 / AC1-G2

SINGLE PHASE | 3 ~ 6kW

Models H1-3.0, H1-3.7, H1-4.6, H1-5.0 and H1-6.0-E-G2, plus the AC-coupled AC1-G2. Supports an EQ4300 stack of 1 Master + 1 to 6 Slaves (2 to 7 modules).

Fox ESS KH / KA series

SINGLE PHASE | 7 ~ 10.5kW

The higher-power single-phase range for larger homes. Supports an EQ4300 stack of 1 Master + 1 to 6 Slaves (2 to 7 modules).

Fox ESS H3 Smart

THREE PHASE | 5 ~ 15kW

Models H3-5.0 to H3-15.0-Smart with a single battery input. Supports an EQ4300 stack of 1 Master + 1 to 6 Slaves (2 to 7 modules).

Fox ESS H3 Pro

THREE PHASE | 15 ~ 30kW

Two independent battery inputs. Each stack needs 1 Master + at least 2 Slaves (3 to 7 modules per stack), so a dual-stack system uses 2 Masters and up to 12 Slaves (14 modules).

Matching the stack to the inverter

Each stack connects to the inverter battery input over CAN through the Master module. The module count you can use depends on the inverter family, so pick the stack size from the table above, then confirm the combination against the Fox ESS inverter and battery configuration guide.

Battery power depends on stack size

Maximum charge and discharge current is 50A per stack, so the battery power you can draw depends on the number of modules and the inverter you pair them with. Check the Fox ESS configuration guide for the exact figure for your combination.

Installation and safety

Install only through a qualified electrician or MCS-registered installer in line with BS 7671 and the manufacturer manual, and notify the DNO under G98/G99 where required. Fox ESS EQ series guidance specifies 10 ~ 16mm² battery cable and a 63A battery breaker for overcurrent protection.

Specifications

Module

Model

EQ4300-S (Slave)

Replaces

CS4300H slave module (ECS4300H range)

Module role

Slave: battery expansion module, requires a Master

Battery type

LiFePO₄ prismatic cell

Module capacity

4.32kWh

Communication

CAN (via the stack Master)

Display

1 × LED

Electrical characteristics (stack level)

Depth of discharge

90%

Battery pack round-trip efficiency

>95%

Cycle life

≥6000 cycles (25°C, 90% DoD, 0.5C charge and discharge)

Recommended discharge current

37.5A

Max. charge / discharge current

50A

Peak discharge current

65A for 60 seconds

Scalability

Max. 7 modules in series (1 Master + 6 Slaves), up to 30.24kWh

Operating conditions

Installation location

Outdoor or indoor (floor stand)

Operating temperature

Charge: 0 ~ 55°C | Discharge: -10 ~ 55°C

Charge derating

Applies between 0°C and +15°C

Storage temperature

-10 ~ 40°C

Cooling method

Natural convection

Humidity

5 ~ 95% (non-condensing)

Altitude

Max. 2,000m

Certificates and protection

Ingress protection

IP65

Safety

IEC 62619

EMC

IEC 61000-6-1/2/3/4

Transportation

UN38.3

EQ4300 stack configurations

Every configuration below uses one EQ4300-M Master plus the number of EQ4300-S Slaves shown.

Stack

Composition

Nominal capacity

Nominal voltage

Operating voltage

W × H × D (mm)

Weight

EQ4300-L2

1 Master + 1 Slave

8.64kWh

115.2 V

97.2 ~ 131.4 V

570 × 368 × 380

78.5 kg

EQ4300-L3

1 Master + 2 Slaves

12.96kWh

172.8 V

145.8 ~ 197.1 V

570 × 506 × 380

115.5 kg

EQ4300-L4

1 Master + 3 Slaves

17.28kWh

230.4 V

194.4 ~ 262.8 V

570 × 644 × 380

152.5 kg

EQ4300-L5

1 Master + 4 Slaves

21.60kWh

288 V

243 ~ 328.5 V

570 × 782 × 380

189.5 kg

EQ4300-L6

1 Master + 5 Slaves

25.92kWh

345.6 V

291.6 ~ 394.2 V

570 × 920 × 380

226.5 kg

EQ4300-L7

1 Master + 6 Slaves

30.24kWh

403.2 V

340.2 ~ 459.9 V

570 × 1058 × 380

263.5 kg

Frequently asked questions

Can a Slave be used without a Master?

No. The EQ4300-S is a battery module only. Every stack needs an EQ4300-M Master to manage the stack and communicate with the inverter.

How many Slaves can I add to one Master?

Up to 6 Slaves per Master, a total of 7 modules and 30.24kWh nominal capacity. A single-phase or H3 Smart system needs at least 1 Slave, and an H3 Pro stack needs at least 2.

Does the EQ4300-S replace the CS4300H?

Yes. The EQ4300 range has superseded the ECS4300H range, and the EQ4300-S is the current CS4300H slave equivalent.

Can I add EQ4300 Slaves to an older ECS4300H stack?

Yes, EQ4300-S modules can be paired with an existing ECS4300H stack and its CM4300H master, but you should confirm compatibility with your original modules before ordering. The battery warm-up function is disabled in a mixed stack.

Which Fox ESS inverters can I use?

The H1-G2 / AC1-G2, KH / KA, H3 Smart and H3 Pro ranges, with the Master connecting the stack to the inverter over CAN.

Can I mix EQ4300 Slaves with other EQ models?

Use matching EQ4300 modules within a stack. Other EQ models such as EQ4800 use their own Master and Slave modules.

Where can I install it?

Outdoor or indoor on the floor stand, rated IP65, in 5 ~ 95% non-condensing humidity and at altitudes up to 2,000m.

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