## 5 Validation Results
### Gothenburg
The charging current decay (\(\beta\)) of 0.23, when battery SoC exceeds 90%, accurately models the measured charging current. There is a deviation between the measured SoC and simulated SoC at two points; one when the bus was standing idle and the measured SoC showed greater than expected energy usage for an idle vehicle, and the other when the reference speed of the bus was 83 km/h, which exceeded the modeled maximum speed of the bus of 80 km/h. Figure 11 shows the results of the May 29 th demonstration based on the assumptions listed in Table 6. The total demonstration was conducted over 12.5 h; however, the measurements are only available after the 5 h mark. The bus was charged using an opportunity charger, with a rated power of 450 kW at 14 different locations; all the charging events were short in duration. For this demonstration, all charging events occurred entirely in the CV mode. Unlike the other demonstrations, which were modeled with high passenger loads, this one is modeled with only the driver to account for the minimal energy utilization observed. There is a deviation between the measured SoC and simulated SoC at a few locations; the deviations are most likely due to inaccurate battery models for LFP battery chemistry above 90% SoC. The deviations in the beginning can be explained by the fact that the measurements prior to the 5 h mark are not presented; thus, it was not possible to determine the state of the bus prior to the start of the simulation. The deviation at the end was most likely due to a more efficient energy recovery process during regenerative braking than was accounted for in the vehicle model. There is a deviation between the measured SoC and simulated SoC at a few locations in Figure 11; the deviations are most likely due to inaccurate battery models for LFP battery chemistry above 90% SoC. The deviations in the beginning can be explained by the fact that the measurements prior to the 5 h mark are not presented; thus, it was not possible to determine the state of the bus prior to the start of the simulation. The deviation at the end was most likely due to a more efficient energy recovery process during regenerative braking than was accounted for in the vehicle model. One of the clear outcomes of the validation process was an accurate determination of the current decay factor (\(\beta\)) during the CV mode of charging and the CC/CV cutoff SoC value. It is understood that after the bulk charging phase of a battery in CC mode, the charging switches to the CV mode, where the current reduces to a trickle. This reduction of the current was modeled as an exponential decay once the battery SoC exceeds 87.5%. The decay amount is given as:  
\[ \begin{split}\text{Iout}=&\quad\left|\text{I}_{ \text{max\_cc}}\times\text{e}^{\beta\times(\text{SoC}-90)},\quad\text{SoC}>87.5 \\ &\quad\left|\text{I}_{\text{max\_cc}},\quad\quad\quad\quad\quad \quad\quad\quad\text{otherwise}\end{split} \right. \tag{2}\]  
where \(\text{I}_{\text{max\_cc}}\) is the maximum charging c-rate during the CC charging mode (-3C for an LFP battery chemistry), and \(\beta\) is the decay factor; it was found that a \(\beta\) of 0.23 models the charging current that gives the closest correlation between the measured and simulated battery SoC profile during charging. Figure 10: Validation of the May 27 th demonstration of 12 m bus in Gothenburg city using the estimates in Table 6. (**a**) Scenario inputs, (**b**) Scenario outputs and validation. Figure 11: Validation of the May 29 th demonstration of 12 m bus in Gothenburg city using the estimates in Table 6. (**a**) Scenario inputs, (**b**) Scenario outputs and validation.