Battery heat generation that occurs during battery charging and discharging can lead to excessive and non-uniform battery temperature in the battery pack. As a result, the battery is more vulnerable to rapid degradation and short cycle life. Effective heat dissipation methods therefore become crucial. In the present study, sawtooth waves with linearly increasing wave amplitude and an inlet notch on the distribution plenum (DP) have been introduced in a typical Z-type battery thermal management system (BTMS) to maximise the cooling effectiveness of the System. Numerical analysis is carried out to investigate the effect of various geometric parameters such as saw tooth wave position, saw tooth wave amplitude, saw tooth wave base width, inlet notch width, and inlet notch height on the performance of BTMS. Velocity contours, streamlines, temperature contours, and maximum battery temperature plots are used to discuss the effects of various factors on the operation of a BTMS. Compared with the typical Z-type BTMS, the modified enclosure design reduced the maximum average battery temperature ( T max ) and maximum temperature differential within the battery pack ( Δ T max ) by 5.11 and 9.01 K respectively, which are 1.56% and 94.90% less than the typical Z-type BTMS respectively.