Issue with Increased Cycles in Simulation Output

[lappemic]

Hello PyBaMM Community,

I have been working on a simulation using the SPM model with specific parameter values and a custom drive cycle. My initial setup performs well for a lower number of cycles (actually just for <3), but as I increase the number of cycles to 3 or more, the output becomes inaccurate. Specifically, I do not get the expected 3 drive cycles in one complete cycle.

Here is the code snippet for reference:

import pybamm
import pandas as pd

# Parameter setup
parameter_values = pybamm.ParameterValues("Chen2020")
parameter_values.update({"SEI kinetic rate constant [m.s-1]": 1e-12})
#parameter_values.update({"SEI kinetic rate constant [m.s-1]": 1e-14})
model = pybamm.lithium_ion.SPM({
    "thermal": "lumped", 
    "SEI": "reaction limited",
    "SEI film resistance": "distributed", 
    "SEI porosity change": "false"
})
pybamm.set_logging_level("ERROR")

# Number of cycles
cycles = 2

# Load drive cycle
drive_cycle = pd.read_csv("pybamm/input/drive_cycles/WLTC.csv", comment='#', header=None).to_numpy()

# Scale the current
scale_factor = 0.1
drive_cycle[:, 1] *= scale_factor

# Define experiment
experiment = pybamm.Experiment(
    [
        (
            pybamm.step.current(drive_cycle),
            "Rest for 1 hour",
            pybamm.step.current(drive_cycle),
            "Rest for 1 hour",
            pybamm.step.current(drive_cycle),
            "Rest for 1 hour",
            "Charge at 1C until 4.2V",
            "Hold at 4.2V until C/50"
        ),
    ] * cycles,
)

# Run simulation
sim = pybamm.Simulation(
    model, parameter_values=parameter_values, experiment=experiment
)

sol = sim.solve(save_at_cycles=10)
sol.plot()

As mentioned, the simulation runs as expected for a small number of cycles, but when increasing the cycle count, the output does not correctly reflect the three drive cycles in one complete cycle.

I am unsure what might be causing this. Could it be an issue with how the experiment is defined or perhaps how the cycles are being handled in my code? Any insights or suggestions to troubleshoot this issue would be greatly appreciated.

Thank you in advance for your help!

Best regards,
Michael