Battery Cooling Glossary

A solid-state welding process. A rotating tool friction-heats the seam between two abutting aluminum panels, softening but not melting the metal; the tool shoulder consolidates the stirred metal behind it into a fully bonded joint. Result: a solid-state joint structurally indistinguishable from the parent metal — no heat-affected zone weakening, no porosity, no thermal distortion. For battery cold plates, FSW joints leak roughly 30× less over a 10-year service life than brazed equivalents. Equipment cost $400K–1.2M per machine. Common models: Dahenergy DH-FSW-1825A, ESAB FSW, MTS, Bond Technologies.

The global automotive sector quality management standard, developed by the International Automotive Task Force, published in 2016 to replace ISO/TS 16949. Builds on ISO 9001:2015 with automotive-specific additions: mandatory PPAP, statistical process control on key characteristics, PFMEA/DFMEA, traceability, customer-specific requirements (CSR), 8D corrective action. Any part going on a vehicle needs an IATF-16949-certified supplier. Re-certification every 3 years, surveillance audits every year. "Zero non-conformities" is the meaningful supplier-quality signal — vendors holding it for several consecutive years are operationally far ahead of recently-certified ones.

A flat aluminum structure with internal coolant channels, sandwiched between battery cells and the cooling circuit. Its job is to transfer heat from cells into circulating coolant. Commercial-vehicle and ESS cold plates are typically 8–25mm thick, 0.6–2m long. The two aluminum panels are joined by brazing, TIG welding, or FSW — the joint method directly determines 10-year leak rate and pack-level temperature uniformity. Common alloys: 6061, 6063, 1100 series.

A vehicle architecture with traction-battery system voltage at 1500V (vs older 800V platforms). At constant power, current halves, copper losses halve, charging is faster. But three things change: series cell count doubles, insulation spacing per IEC 60664-1 jumps from 4.0mm to 8.0mm, cell-to-cell uniformity tolerance tightens from ±5°C to ±1.5°C. This means air cooling is no longer viable and single-zone liquid cooling is insufficient — you need multi-zone liquid cooling with active flow balancing. 1500V is in mass production for mining trucks, heavy haulers, and utility-scale ESS containers; rolling into mainstream commercial vehicles from 2026.

A statistical metric of how reliably a production process stays within tolerance. Calculation combines distance from process mean to spec midpoint with process standard deviation. Quick reading: Cpk ≥ 1.33 = capable (defect rate < 64 ppm), Cpk ≥ 1.67 = industry-leading (< 0.6 ppm), Cpk < 1.0 = process can't reliably meet spec. IATF 16949 requires Cpk ≥ 1.33 on key characteristics with trend tracking. For cold plates, the key characteristics are usually leak rate and pressure drop. Vendors that say they 'run SPC' but can't produce Cpk trend charts are not actually running SPC.

Protection rating per IEC 60529. First digit 6 = dust-tight; second digit 7 = temporary immersion protection (1 m depth, 30 min). Commercial vehicle battery enclosures almost universally require IP67 (buses, mining trucks, heavy trucks see water fording and pressure washing). Note: IP67 does NOT mean continuous immersion — that's IP68. Verifying IP67 means an IEC 60529 third-party test report (TÜV, SGS), not vendor self-testing.

The standardized supplier-qualification submission process used across the automotive industry. Covers 18 elements: design records, engineering change documents, customer engineering approval, DFMEA, process flow diagram, PFMEA, control plan, MSA studies, capability studies, sample parts, appearance approval, material certifications, sample inspection report, etc. Used for full-scope validation of a new part before mass production. OEMs typically require PPAP Level 3 (full submission with sample parts approved by customer). Clearing PPAP first time is a meaningful signal of supplier maturity.

A systematic analysis of every potential failure mode in a production process. Each failure gets severity (S), occurrence (O), detection (D) ratings; RPN = S × O × D. High-RPN modes must have controls implemented. Example for cold plate production: 'FSW tool wear causes incomplete weld penetration' is a failure mode — severity 9 (leak risk), occurrence 4 (depends on tool inspection cadence), detection 3 (in-line leak test catches it), RPN = 108. That RPN must be controlled via tool-life monitoring + 100% in-line leak test. A vendor handing you a blank PFMEA template hasn't actually implemented one.

An uncontrolled chain reaction where rising battery cell temperature accelerates the chemical reactions inside, which generate more heat, which accelerates the reactions further. Once a critical temperature is crossed (~150°C for NCM lithium cells, ~200°C for LFP), the cell goes exothermically out of control and can ignite or vent flammable gas. Pack-level thermal runaway can propagate to every cell within minutes. Cooling system failure — e.g., a cold plate leaking coolant into the battery enclosure — is one of the primary external triggers. Commercial vehicle battery designs typically require 'single-cell thermal runaway must not propagate for 60 minutes' as a minimum safety threshold.

The engineering system that keeps a battery within its optimal temperature window (~25–35°C for lithium chemistries). Includes: cooling under load, heating in cold-start conditions, cell-to-cell uniformity control, and thermal-runaway containment when a single cell fails. Commercial-vehicle BTM typically combines liquid cold plates, a coolant pump-and-radiator unit, BMS temperature control, insulation, and venting paths. Pack-level uniformity inside ±1.5°C is the safety threshold for high-voltage (1500V) platforms; ±5°C is acceptable at 800V.

A lithium battery cathode chemistry, formula LiFePO4. Compared to NCM (nickel-cobalt-manganese), LFP has lower energy density (~160 Wh/kg vs NCM ~250 Wh/kg) but longer cycle life (3000–6000 cycles vs 1500–2500), better thermal stability (thermal runaway at ~200°C vs NCM ~150°C), and lower cost (no cobalt). Commercial vehicles and ESS use LFP heavily for cycle-life and safety reasons. 280Ah is the current mainstream ESS cell format, driving 1P52S/1P104S module architectures and the cold-plate dimensions matched to them.

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