Prevent Dew & Reduce Thermal Load: A Complete Guide to ESS Cold Plate Bottom Foaming

Bottom foaming is a widely adopted thermal management solution for energy storage liquid cooling plates. It refers to closed-cell PU foam applied on the outer bottom surface of liquid cooling plates (between the cold plate and battery enclosure base plate), NOT foaming inside the cooling channels. This technology is highly suitable for commercial & industrial energy storage systems and bus battery packs.

1. Condensation Prevention (Primary Benefit) When the liquid cooling plate works at low temperatures, large temperature differences between the aluminum surface and ambient air cause moisture condensation, which may trigger short circuits on high-voltage components. The closed-cell foam layer isolates air and effectively eliminates dew risk, an essential requirement for ESS under large day-night temperature fluctuations.
2. Thermal Insulation With thermal conductivity ≤0.05 W/(m·K), the foam blocks external heat or cold intrusion. It stabilizes cell operating temperature and cuts power consumption of the liquid cooling system to reduce cooling load.
3. Vibration Buffering & Bottom Protection The foam absorbs vibration and impact from gravel or bumps, safeguarding the aluminum liquid cooling plate. It provides uniform support to keep the cold plate tightly attached to thermal conductive silicone. This prevents rising thermal resistance caused by poor thermal contact after long-term vibration.
4. Waterproof Sealing & Lightweight Design High closed-cell rate (>90%) delivers extremely low water absorption. Compared with separately assembled thermal insulation cotton, in-situ spray foaming forms an integrated layer, reduces part count and simplifies pack assembly.

• Flame rating: UL94 V-0, low smoke & halogen-free to meet strict ESS safety standards
• Operating temperature: -40℃ ~ 85℃ for wide-range energy storage working conditions
• Manufacturing methods: Robotic high-pressure spray foaming (preferred, fully covers complex contours and corners); Pre-fabricated foam sheet (POE/silicone foam, for small-batch orders)

1. Complete hydraulic leak testing of liquid cooling plates, clean and pretreat the aluminum bottom surface to improve adhesion.
2. Fix workpieces with tooling, then robotic arms spray PU raw materials under high pressure.
3. Raw materials expand and cure in place to form an integrated thermal insulation layer.
4. Edge trimming, thickness inspection and sampling test for bonding strength.
5. Deliver the finished cold plates to battery pack assembly line.

Common foam thickness: 3~10 mm, customized based on thermal simulation and structural clearance of each project.

1. Adhesion Performance: Repeated thermal cycling brings thermal expansion and contraction. The foam layer must not peel off from the aluminum plate; interfacial bonding strength is critical.
2. No Damage to Cold Plate Substrate: The foaming process is temperature-controlled. It will not damage friction stir welding seams or deform internal cooling channels.
3. Closed-cell Rate Control: Open-cell foam absorbs water and is forbidden for energy storage projects.
4. Slight weight increase; thickness and compression allowance should be calculated in BOM.

Trumony Aluminum Limited specializes in customized aluminum thermal management components for new energy and energy storage industries. Our product portfolio covers extruded liquid cooling plates, friction stir welded battery bottom enclosures, and bottom foaming services for ESS cold plates. We deliver reliable thermal solutions for bus battery packs and stationary energy storage systems across Europe, North America and Asia. Our engineering team supports custom thickness design, thermal simulation verification and strict quality inspection to satisfy your battery pack safety and thermal stability requirements. Contact us to discuss your liquid cooling plate foaming project today.