Used high-voltage battery stack control enclosure

What it actually is The two silver modules inside are: BMS Stack Controller — the brains. It talks to cell interface modules, calculates SOC/SOH, handles faults, and talks to the outside world. BMS Power Interface — handles high-current contactors, current shunt measurement, stack voltage, and auxiliary power distribution. Together they form a single-stack high-voltage BMS (G4 generation, typically rated up to 1250 V DC). The rest of the box is the power hardware that the BMS controls. Front-panel connections B+ / B– — Battery stack positive and negative. P+ / P– — DC bus / pack output side (after the contactors). COM (three circular connectors) — Custom-wired communication and control ports. The handwritten labels (“OUT 1”, “HMI 2”, “#3 33A”) are integrator markings. These usually carry a mix of: Ethernet / Modbus TCP RS-485 / Modbus RTU CAN GPIO / interlock / HMI signals What’s inside (from the photos) Gigavac high-voltage DC contactors (main + pre-charge) High-current fuse (looks like a 350 A class fuse) Current shunt Isolated TOBSUN DC-DC converters (auxiliary 24 V power for the BMS and contactors) Wiring for Link Bus (goes out to separate Cell Interface modules that sit on the actual battery modules) The Cell Interface boards themselves are not in this box — they live on the battery modules and daisy-chain back to the Stack Controller via the Link Bus. Communications capabilities The Stack Controller supports: Modbus TCP over Ethernet (primary interface + web-based Operator Interface) Modbus RTU over isolated RS-485 Isolated CAN 2.0 USB (configuration / firmware) Configurable GPIO This is the same comms stack used in commercial utility-scale and C&I energy storage systems. It speaks SunSpec / MESA models so inverters and site controllers can talk to it directly. Typical use This style of enclosure is common in: Used / surplus commercial battery energy storage systems (BESS) Custom high-voltage Li-ion or LiFePO4 stacks Second-life EV battery packs that were converted into stationary storage