proper way of setting initial SOC in lead acid model

[csengerib]

Dear all,
I am using pybamm.lead_acid.Full() model, and I could set the initial SOC by changing the model parameter "Initial State of Charge" to the required value. It was worked well on v23.1 version of PyBaMM. However, it is not working on v23.5.

Example code:

      import pybamm
      
      model = pybamm.lead_acid.Full()
      param = pybamm.ParameterValues("Sulzer2019")
      param['Initial State of Charge'] = 0.5
      sim = pybamm.Simulation(model, parameter_values=param)
      sim.solve([0, 3600])
      
      solution = sim.solution
      U_initial = solution['Terminal voltage [V]'].data[0]
      SOC_initial = solution['State of Charge'].data[0]
      print(f'{SOC_initial=}   {U_initial=}')

running the same code using the different versions, the output of last line is different:

• v23.1: SOC_initial=49.999999999999915 U_initial=2.0119020542246284

• v23.5: SOC_initial=100.00000000000023 U_initial=2.160802233175138

In the case of v23.5, the SOC remained at 100% instead of changing to 50%.

I would like to ask what is the proper way to set the initial SOC in lead acid model?
(Note: sim.solve([0, 3600], initial_soc=0.5) not working too.)

Thanks in advance!