Hello, I want to know why my code is not working properly, please help !!!

[KwanjuEUN]

I try to make different nominal capacity battery data with same compound battery (In this case, LCO).

Below code is working in my environment and I can take the excel file. However, when I change the capacity value, experiment condition is changed but nominal capacity is same with default.

Anyone who know this problem, please help !!!

import pybamm
import numpy as np
import pandas as pd

def simulate_battery_chemistry(chemistry_name, capacity):
    # 1. Define the model (including SEI and lithium plating)
    options = {
        "SEI": "ec reaction limited",
        "SEI film resistance": "distributed",
        "SEI porosity change": "true",
        "lithium plating porosity change": "true",
    }
    model = pybamm.lithium_ion.DFN(options=options)

    # 2. Define the battery chemistry
    chemistry = pybamm.parameter_sets[chemistry_name]
    parameter_values = pybamm.ParameterValues(chemistry)
    parameter_values.update({"Nominal cell capacity [A.h]": capacity})

    print("Updated Nominal cell capacity [A.h]:", parameter_values["Nominal cell capacity [A.h]"])

    # 3. Set the experimental conditions (now for 200 cycles)
    experiment = pybamm.Experiment(
        [("Discharge at 1 C until 2.7V", # NMC = 2.5V / LCO = 2.7V
          "Rest for 15 minutes",
          "Charge at C/2 until 4.2 V",
          "Hold at 4.2 V until C/20",
          "Rest for 15 minutes")] * 10
    )

    # 4. Run the simulation
    sim = pybamm.Simulation(model, experiment=experiment, parameter_values=parameter_values)
    
    # Increase the maximum timestep size
    sim.solver.dt_max = 1e3  # Adjust this value as needed
    
    sim.solve()

    return sim

def segment_cycles_based_on_current(current, time, voltage):
    """Segment the data based on the current pattern to define each cycle."""
    cycles = []
    i = 0
    cycle_count = 0

    while i < len(current) - 1 and cycle_count < 10:
        # Check for the discharge phase (positive current)
        if current[i] > 0:
            start_idx = i
            while i < len(current) - 1 and current[i] > 0:
                i += 1

            # Rest after discharge (current ~ 0)
            while i < len(current) - 1 and abs(current[i]) < 1e-3:
                i += 1

            # Charging phase (negative current)
            while i < len(current) - 1 and current[i] < 0:
                i += 1

            # Rest after charge (current ~ 0)
            while i < len(current) - 1 and abs(current[i]) < 1e-3:
                i += 1

            end_idx = i
            cycles.append((start_idx, end_idx))
            cycle_count += 1
        else:
            i += 1

    return cycles

def save_cycles_to_excel(solutions, filename):
    # Desired resolution per cycle
    num_points_per_cycle = 10000

    with pd.ExcelWriter(filename) as writer:
        for chem_key, sol in solutions.items():
            time = sol.solution["Time [s]"].entries
            current = sol.solution["Current [A]"].entries
            voltage = sol.solution["Voltage [V]"].entries

            # Segment the cycles based on the current pattern
            cycles = segment_cycles_based_on_current(current, time, voltage)

            for cycle_num, (start_idx, end_idx) in enumerate(cycles):
                # Interpolating within each cycle
                cycle_time = np.linspace(time[start_idx], time[end_idx-1], num_points_per_cycle)
                interpolated_current = np.interp(cycle_time, time[start_idx:end_idx], current[start_idx:end_idx])
                interpolated_voltage = np.interp(cycle_time, time[start_idx:end_idx], voltage[start_idx:end_idx])

                df = pd.DataFrame({
                    "Time [s]": cycle_time,
                    "Current [A]": interpolated_current,
                    "Voltage [V]": interpolated_voltage
                })
                df.to_excel(writer, sheet_name=f"Cycle_{cycle_num+1}", index=False)

            print(f"Saved data for {chem_key} to {filename}")

# Run simulations for each battery chemistry
chems = ["Ramadass2004"] # LCO = Ramadass2004 / NMC = Marquis2019, Ecker2015
**capacities = [0.5]** # LCO = 1 / NMC = 0.68, 0.15625 (default capacity)
solutions = {}


for chem in chems:
    print(f"Default Nominal cell capacity [A.h] for {chem}:", pybamm.parameter_sets[chem]["Nominal cell capacity [A.h]"])
    for cap in capacities:
        key = f"{chem}_{cap}Ah"
        solutions[key] = simulate_battery_chemistry(chem, cap)

# Save the results to an Excel file
save_cycles_to_excel(solutions, "filename_0.5_LCO_R_C10.xlsx")

[brosaplanella]

Nominal capacity is only used to convert between C-rate and current, changing it has no effect on the true capacity of the battery. To change that, you need to update physical parameters that affect the true capacity of the battery (e.g. electrode thickness).

[KwanjuEUN]

Thanks, today I solve the problem with changing the electrodes thickness. Is there any other solutions? 2023년 11월 9일 (목) 오후 7:13, Ferran Brosa Planella ***@***.***>님이 작성:

…

Nominal capacity is only used to convert between C-rate and current, changing it has no effect on the true capacity of the battery. To change that, you need to update physical parameters that affect the true capacity of the battery (e.g. electrode thickness). — Reply to this email directly, view it on GitHub <#3493 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/A7MHWVVVKOIMPLHLHQKKORLYDSUDPAVCNFSM6AAAAAA62MMVLWVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM3TKMRQGY3DC> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[brosaplanella]

See #3458 for more details.

[KwanjuEUN]

Got it, thanks! 2023년 11월 9일 (목) 오후 7:17, Ferran Brosa Planella ***@***.***>님이 작성:

…

See #3458 <#3458> for more details. — Reply to this email directly, view it on GitHub <#3493 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/A7MHWVUS4JT277MI4FQ23WTYDSUTVAVCNFSM6AAAAAA62MMVLWVHI2DSMVQWIX3LMV43SRDJONRXK43TNFXW4Q3PNVWWK3TUHM3TKMRQG4YDG> . You are receiving this because you authored the thread.Message ID: ***@***.***>