Hybrid thermoelectric and air cooling of a 104-cell lithium-ion battery pack coupled with thermal modelling of cooling performance, power cost and safe operating limits

Thermoelectric coolers (TECs) are proposed to augment forced-air battery thermal management, and hybrids are commonly reported to exceed the combined performance of their constituent modes. Such assessments prescribe the thermoelectric hot-side temperature rather than solving for it, leaving the reported interaction unverified. This study develops a coupled electro-thermal model of a 104-cell (13S8P) cylindrical pack in a staggered duct in which cell, air, cold-plate and hot-side temperatures are solved simultaneously from energy balances and fan power is derived from the tube-bank friction factor. Heat generation follows the Bernardi formulation, convection the Zukauskas correlation, and module properties come from catalogue data. The model reproduces a closed-form analytical solution to 1×10¹² K, with a grid convergence index of 0.06%. Additivity was assessed on a temperature basis⁻ (S=0.607±0.102, 48 conditions), where the hybrid achieves substantially less than the sum of the individual depressions, and on a capacity basis (SQ=0.994±0.079, 72 conditions), where it is additive within scatter. Prescribing the hot side at Tamb+10 K standalone against Tamb+3 K hybrid raises SQ to 1.096, identifying it as the source of the reported enhancement. Deactivating the thermoelectric stage while retaining the cold plate recovers 25–60% of the uniformity improvement for under 9% of the parasitic power. At equal electrical power, augmentation is advantageous in 45% of conditions. With airflow limited to 1.2 m s¹, fan-only regulation exceeds 45 °C for 1033 s of a 2400 s profile at 30 °C⁻ ambient whereas the hybrid remains below the limit, and across 2000 Monte Carlo builds at 60 A the limit is exceeded in 99.8% of forced-air against 1.2% of hybrid cases. Fixed-current operation overcools the pack at low load, and the cold plate falls below the dew point across 22% of hybrid operating points. A fan-first control hierarchy with a dew-point-limited thermoelectric stage is recommended.