Why Is My Simulation Loop Much Slower Than a Single Experiment?

[ErfanSamadi1998]

Hi,

I noticed a big difference in the time it takes to run two similar simulations in PyBaMM, and I don't understand why. Here's what I mean:

Case 1:

This code runs in 12.6 seconds:

import pybamm

options = {"thermal": "lumped"}
model = pybamm.lithium_ion.DFN(options=options)
parameter_values = pybamm.ParameterValues("Chen2020")
experiment = pybamm.Experiment(["Charge at 1 A for 1 second"], period="1 second")
sim = pybamm.Simulation(model, parameter_values=parameter_values, experiment=experiment)
sol = sim.solve()

voltage_entries = sol["Terminal voltage [V]"].entries
voltage = float(voltage_entries[-1])
print(voltage)

def battery(current):
    global sol
    
    new_model = model.set_initial_conditions_from(sol, inplace=False)
    sim = pybamm.Simulation(new_model, parameter_values=parameter_values, experiment=experiment)
    sol = sim.solve()
    
    voltage_entries = sol["Terminal voltage [V]"].entries
    voltage = float(voltage_entries[-1])

    return voltage

for i in range(10):
    current = 1
    voltage = battery(current)
    print(voltage)

Case 2:

This code, which does the same total charge duration (11 seconds), runs in 1.2 seconds:

import pybamm

options = {"thermal": "lumped"}
model = pybamm.lithium_ion.DFN(options=options)
parameter_values = pybamm.ParameterValues("Chen2020")
experiment = pybamm.Experiment(["Charge at 1 A for 11 seconds"], period="1 second")
sim = pybamm.Simulation(model, parameter_values=parameter_values, experiment=experiment)
sol = sim.solve()

voltage_entries = sol["Terminal voltage [V]"].entries
print(voltage_entries)

Question:

Both codes are charging the battery for 11 seconds. The only difference is that in the first case, I run the simulation in a loop for 1 second each time and update the initial conditions.

Why is the first case much slower? Is there a way to make the loop faster?

Thanks!

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