The Fox ESS CQ16 BMS Control Box (branded by the manufacturer as the CQ BOX) is the
master battery management unit required by every Fox ESS CQ16 high-voltage battery system. It monitors
and coordinates the connected CQ16 modules across an operating voltage range of 101–1000Vdc, managing
up to 240A of charge and discharge current with ±0.5% FSR voltage measurement accuracy and
>92% charge/discharge efficiency, communicating with the Fox ESS H3 Plus inverter via CAN bus.
101–1000V
Operating Voltage Range
240A
Max Charge/Discharge
±0.5% FSR
Voltage Accuracy
64.28–241.05kWh
Rated Energy Range
One Required Per System
Every Fox ESS CQ16 battery system requires exactly one BMS Control Box, regardless of the number of battery stacks connected. It must be installed and commissioned by a qualified electrician.
Sold Separately from Battery Modules
The Control Box is not included with individual CQ16 battery modules and must be ordered as a separate line item to complete a working battery system.
System Role
The Control Box acts as the central battery management system (BMS), aggregating voltage, current and communication data from every connected CQ16 module stack and relaying it to the Fox ESS H3 Plus inverter over CAN.
Wide Operating Voltage Window
Supporting 101–1000Vdc, the Control Box accommodates the full voltage range of a CQ16 system as it scales from the minimum 4-module configuration up to the maximum 15-module, 241.05kWh build.
Precise Voltage Monitoring
A ±0.5% FSR total voltage measurement accuracy gives the connected inverter reliable state-of-charge data, supporting safe and efficient charge/discharge management across the whole battery bank.
Bidirectional Current Sensing
Current measurement across a −240A to +240A range allows the Control Box to track both charging and discharging in real time, protecting the battery stack from over-current conditions.
CAN Bus Communication
A dedicated CAN communication interface links the Control Box directly to the Fox ESS H3 Plus inverter, forming the data backbone for the whole battery system's charge/discharge coordination.
High Round-Trip Efficiency
A rated charge/discharge efficiency above 92% means minimal energy loss is introduced by the management layer itself, preserving the round-trip efficiency of the wider storage system.
Matched Form Factor
Sharing the same 390 × 235 × 810mm footprint as the CQ16 battery modules, the Control Box stacks alongside battery banks for a consistent, space-efficient plant room installation.
| Battery Management System |
| Model |
CQ BOX |
| Operating Voltage Range |
101 – 1000 Vdc |
| Max. Charge/Discharge Current |
240 A / 240 A |
| Total Voltage Measurement Accuracy |
±0.5% FSR |
| Current Measurement Range |
−240 to +240 A |
| Communication Interface |
CAN |
| Charge/Discharge Efficiency |
>92% |
| Rated Energy Range (System) |
64.28 – 241.05 kWh |
| General Specification |
| Dimensions (W×H×D) |
390 × 235 × 810 mm |
| Weight |
29 ±1 kg |
| Operating Temperature |
Charge: 0–55°C / Discharge: −10–55°C |
| Storage Temperature |
−10 to 55°C |
| Humidity |
5 – 95% |
How many BMS Control Boxes does my system need?
Just one per CQ16 battery system, regardless of how many battery stacks or modules are connected — it acts as the single master battery management unit.
Is the Control Box included with the CQ16 battery modules?
No, it is sold as a separate item and must be ordered alongside the battery modules, battery bases and cable packs to complete a working system.
What voltage range does the Control Box support?
It operates across 101–1000Vdc, covering the full voltage span of a CQ16 system from its minimum to maximum configuration.
How does the Control Box communicate with the inverter?
It connects to the Fox ESS H3 Plus inverter via CAN bus, relaying real-time voltage, current and system status data.
What is the charge/discharge efficiency of the Control Box?
The unit is rated at greater than 92% charge/discharge efficiency, minimising energy loss introduced by the battery management layer.
