Cooling battery cells directly in liquid creates an engineering challenge: keeping that liquid away from electrical equipment.

BYD has filed a patent application for a two-chamber cabinet that separates submerged battery modules from electronics and routes their connections through the upper part of the liquid-filled compartment.

The China National Intellectual Property Administration published the application, numbered CN 122868832 A, on October 5, 2026.

Filed in March 2025, it describes battery cabinets and energy storage equipment that use dielectric fluid to absorb heat directly from the modules.

The design places electrical equipment in a dry upper chamber and battery modules in a wet lower chamber.

Its focus is the boundary between those spaces, where connections must pass through without allowing cooling liquid to reach components intended to remain dry.

Many battery systems remove heat through an indirect cooling arrangement. Liquid circulates inside aluminum cold plates positioned against battery modules, drawing heat through the cell casing and materials between the cells and plates.

Immersion cooling changes that heat-transfer route. Battery modules sit directly in a non-conductive fluid, allowing heat to pass from their wetted surfaces into the surrounding liquid.

This shortens the thermal path, but containing the fluid becomes part of the cabinet’s design. Electrical equipment and connection points that are not intended for immersion still require protection from the liquid.

BYD’s application specifies dielectric cooling fluids, including hydrocarbon- or ester-based formulations. These fluids provide electrical insulation while cooling the submerged modules.

The proposed cabinet divides the battery and its electrical equipment into two isolated compartments.

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