## 4 Results and Discussion
### Performance Prediction and Analysis
For example, the prediction results of Figure 7(c4,c5) fail to reflect the detailed voltage fluctuations of the local cell voltage around the 75 th cell, while the prediction curves of Figure 7(c1,c2,c3) could follow the experimental results with detailed voltage distributions. This is mainly attributed to the dimension-reduction of the voltage output for the model. When the number of data groups diminishes, the data input becomes insufficient for artificial intelligence to anticipate the curve in detail. Furthermore, the peak, as mentioned earlier, and valley of the curves are not shown in these groups, while the curve in these groups clearly illustrates the trend in cell voltages. In Figure 8, groups D4 (6-8-5-50) and D5 (6-8-5-100) reach the curves close to the experimental result of the \(U_{cell}\) and the _range_. However, for groups D1 (6-8-5-5), D2 (6-8-5-10), and D3 (6-8-5-20), there is a gap between the predicted and the experimental curves, and the gap is broader in the groups with fewer data groups. The gap keeps increasing as the load current increases. In Figure 8(b1), all of the predicted and experimental results have lower starting and ending \(U_{cell}\), indicating better cell voltage uniformity. Similarly, the starting and ending _ranges_ of all groups in Figure 8(b2) are also lower than those in Figure 8(a2,c2), as is consistent with the result of \(U_{cell}\). At the starting point, the \(U_{cell}\) difference in all groups is relatively small, but the gap is increasingly broadened at the points where a 330 A load current is applied. Unlike the \(U_{cell}\) difference, the _range_ difference in different groups also increases as the load current increase, but it is evident at a low load current. Under a high load current, the predicted _range_ curves in the D1 (6-8-5-5), D2 (6-8-5-10), and D3 (6-8-5-20) groups show diversion both in the increasing gap between the \(U_{cell}\) predictions of larger group numbers and smaller group numbers at 330 A and in the significantly increasing gap between D3 (6-8-5-20), D2 (6-8-5-10), and D1 (6-8-5-5) at a load current around 650 A. In contrast, the \(U_{cell}\) curve does not show this diversion. Figure 8(b1,b2) shows that D5 (6-8-5-100) and D4 (6-8-5-50) do not fit the experimental results well at a low load current under assembly torque 14 N.m, but that the gap is eliminated at around 330 A. Additionally, the fluctuation of Figure 8(b1,b2) for groups D3 (6-8-5-20), D2 (6-8-5-10), and D1 (6-8-5-5) is higher than the curves of the same groups in Figure 8(a1,a2) or Figure 8(c1,c2). Figure 8 (a1,b1,c1) shows the predicted and tested \(U_{cell}\) under changing currents with different assembly torques and grouping strategies. In the D4 (6-8-5-50) and D5 (6-8-5-100) groups, the predicted outputs match the experimental results closely, but in D3 (6-8-5-20), D2 (6-8-5-10), or D1 (6-8-5-5) the predicted \(U_{cell}\) decreases as the number of the group decreases due to the detail losses in cell voltage distribution as the number of group decreases. Interestingly, D3 (6-8-5-20) has a higher predicted \(U_{cell}\) than that of D4 (6-8-5-50) at the assembly torque of 14 N.m and at the load currents from 500 A to 600 A. This is possibly due to the overall consistency of every five neighboring cells being better than every ten neighboring cells within this load current range. The three figures above also show that when the assembly torque is 14 N.m, the predicted and tested results have the lowest \(U_{cell}\) under different groups. For example, when the current load is 732 A and the assembly torque is 14 N.m, the experimental and predicted results are lower than 5.5 mV. In contrast, when the assembly torque is 12 N.m or 15 N.m, the experimental and the predicted results are around 6.5 mV. However, the assembly torque of 15 N.m is more consistent than that of 12 N.m at low-current loads.