EV Battery Liquid Cold Plate RFQ Checklist

# EV Battery Liquid Cold Plate Aluminum RFQ Checklist

EV battery liquid cold plates are not ordinary aluminum plates with coolant ports. In a battery pack, the cold plate can affect cell temperature uniformity, pressure drop, pack height, thermal-interface compression, leak risk, corrosion exposure, and assembly reliability.

That is why a cold-plate RFQ should not begin with only outer dimensions and annual quantity. A supplier needs to understand the thermal map, coolant circuit, sealing boundary, flatness targets, joining process, inspection scope, and what part of the battery thermal-management assembly is actually being sourced.

This guide is for battery-pack engineers, thermal-system buyers, procurement teams, and SQE reviewers preparing an RFQ for EV battery liquid cold plates, aluminum coolant plates, thermal spreader plates, cast or machined fluid housings, and related aluminum thermal-management parts.

Important supplier-fit note: many battery cold plates are stamped, brazed, roll-bonded, extruded, machined, or friction-stir-welded aluminum assemblies rather than castings. Bohua's fit should be reviewed from the drawing. For casting-plus-machining RFQs, the best-fit opportunities are often aluminum fluid housings, manifolds, covers, mounting structures, end plates, thermal-management housings, and selected cast features around the cold-plate assembly.

For connected Bohua paths, review the leak-tight aluminum casting hub, quality control overview, casting drawing requirements guide, and formal RFQ form.

Why this keyword matters now

Ducker Carlisle's public aluminum-content study separates battery cooling plates into EV-specific aluminum content and notes that thermal-management aluminum content changes materially when battery cooling plates are counted with that family. Eaton's EV liquid-cooling guidance also highlights battery and inverter cooling as a core EV thermal-management challenge.

For sourcing, the point is practical: battery thermal management is a real aluminum demand center, but the winning supplier is the one that understands the RFQ boundary. A quote that ignores pressure drop, leak validation, TIM contact, flatness, and cleanliness may be cheap only because important work was left out.

Start by defining what you are buying

Before sending drawings, state whether the RFQ is for:

• •the liquid cold plate itself
• •a cast or machined aluminum coolant housing
• •an inlet/outlet manifold or end tank
• •a battery tray or enclosure feature that carries coolant routing
• •a mounting plate or thermal interface structure
• •a prototype sample, design validation batch, or production program

This matters because the manufacturing route can be completely different. Eaton's EV cooling guidance notes that battery cold plates can be large and thin, with the fluid path designed to cover as much surface area as possible. If the part is too thin or requires a specific bonded plate construction, a casting supplier should say so early rather than force the wrong process into the quote.

Use a clear RFQ note:

> Please review the drawing for process fit. If the liquid cold plate itself is not a casting fit, quote only the cast or machined aluminum thermal-management parts that match your process capability and list any excluded cold-plate operations.

That sentence protects both buyer and supplier.

Include the thermal map, not just the CAD model

Eaton's custom cold-plate design guidance starts with defining the thermal map: component locations, heat loads, maximum surface temperatures, coolant composition, flow rate, inlet temperature, and available pressure drop. Those inputs affect the circuit concept and whether the supplier can quote the correct machining, joining, and inspection scope.

For a battery cold-plate RFQ, include:

• •cell layout or module footprint
• •heat-load zones or hot-spot map
• •maximum cold-plate surface temperature target
• •thermal-interface material type or compression requirement
• •flatness target under cells or modules
• •coolant type, concentration, and corrosion inhibitors if known
• •flow rate, inlet temperature, and available pressure drop
• •target mass or thickness limit
• •whether CFD, thermal simulation, or test validation is buyer-owned or supplier-owned

If you do not have all thermal data yet, state what is frozen and what is still under design review.

Separate flatness from surface finish

Cold-plate buyers often ask for "good surface finish" when the real issue is contact uniformity. The RFQ should separate:

• •global flatness across the plate
• •local flatness under cell/module contact zones
• •surface roughness for TIM contact
• •burr limits around holes and ports
• •post-coating or post-anodizing dimensional effects
• •whether inspection is by CMM, surface plate, fixture, or customer-specific method

For cast or machined aluminum housings around the cold plate, identify which face is the sealing face, which face is the mounting datum, and which face only needs general machining.

Define coolant path and pressure drop assumptions

Cold-plate quote quality depends heavily on the coolant circuit. Eaton notes that liquid circuits must meet required performance at acceptable pressure drop. If the buyer sends only a CAD model without the flow intent, suppliers may quote different internal passage assumptions.

Include:

• •inlet and outlet locations
• •flow direction and circuit sequence
• •parallel versus serial passages
• •allowable pressure drop
• •minimum wall thickness around channels
• •port thread or hose-interface standard
• •drain, vent, or sensor boss requirements
• •pressure rating and burst-test requirement if applicable
• •cleanliness limits for chips, residues, or particles

For cast fluid housings and manifolds, also state whether passages are as-cast, cored, drilled, plugged, welded, or assembled from multiple parts.

Specify leak-test stage and record format

Eaton's EV liquid cooling page states that cold plates must be tested and manufactured to be leak free, reliable, and durable. For RFQs, avoid saying only "leak test required." That is not enough for comparable quotes.

Ask suppliers to state:

• •leak-test medium: air, helium, water/glycol, or customer-specific fluid
• •test pressure and hold time
• •pass/fail criterion
• •test stage: before machining, after machining, after joining, after coating, or final assembly
• •whether each part, each lot, or only samples are tested
• •fixture responsibility
• •record format: sample report, serial-number record, lot record, PPAP/FAI attachment

For battery components, also clarify whether the test boundary is the coolant circuit only or the entire assembled module boundary.

Treat corrosion and material compatibility as RFQ inputs

Battery cooling circuits may use water-glycol mixtures and corrosion inhibitors. If aluminum parts are joined to dissimilar metals or exposed to specific coolants, the RFQ should include material compatibility expectations.

Include:

• •aluminum grade or acceptable equivalent
• •coolant chemistry and concentration
• •target service temperature range
• •coating, anodizing, passivation, or conversion-coating requirement
• •galvanic corrosion concerns with fasteners, inserts, or tubes
• •salt spray or environmental test requirements if specified by the buyer

If the buyer has a company coolant specification, attach it or reference the exact revision.

Ask for supplier-fit feedback before price lock

For a drawing-ready cold-plate or thermal-management RFQ, ask the supplier to return a process-fit note with the quote:

That table turns the RFQ into a technical comparison instead of a unit-price contest.

What to send Bohua for review

For a battery cold-plate-adjacent aluminum RFQ, send:

• •2D drawing with revision status
• •STEP or IGES model
• •part role in the battery thermal-management assembly
• •target annual volume and sample quantity
• •alloy, temper, coating, or buyer material standard
• •flatness and surface-roughness requirements
• •coolant type, pressure, and leak-test requirement
• •machining datums and critical ports
• •inspection record and traceability scope
• •whether the buyer expects Bohua to quote the full assembly or only casting-plus-machining parts

If drawings are ready, use the formal RFQ form. If the project is NDA-first or the process fit is uncertain, start with the contact page.

Sources used for this RFQ guide

• •Ducker Carlisle 2023 aluminum content public summary
• •Eaton liquid cooling solutions in electric vehicles
• •Eaton custom liquid cold plate design guidance
• •Eaton EV battery liquid cold plate case study

Bottom line

The highest-quality EV battery cold-plate RFQ is not the one with the most CAD files. It is the one that tells suppliers the thermal map, coolant circuit, flatness target, leak-test boundary, corrosion assumptions, record requirements, and exact sourcing scope.

For aluminum casting and machining supplier review, Bohua can assess drawing fit, identify which parts of the thermal-management assembly match casting-plus-machining capability, and route the project to the correct quote path. Submit the drawing pack for RFQ review when the technical boundary is ready.