Issue when trying to use the "number of cells connected in series to make a battery" setting in Prada2013

[skywo1f]

I am trying to simulate a system with 16 lfp batteries in series. I modified the Prada2013 file to reflect that:

"Number of electrodes connected in parallel to make a cell": 4.0,
"Number of cells connected in series to make a battery": 16.0,
"Lower voltage cut-off [V]": 2.5,
"Upper voltage cut-off [V]": 3.65,
"Initial concentration in negative electrode [mol.m-3]": 28831.45783,
"Initial concentration in positive electrode [mol.m-3]": 35.3766672,
"Initial temperature [K]": 298.15,

Then I set the ranges of my experiment:

exp = pybamm.Experiment(
[
(
"Charge at 1 C until 58.4 V",
"Hold at 58.4 V until C/10",
"Rest for 5 minutes",
"Discharge at 1 C until 40 V",
"Rest for 5 minutes",
)
]
)

But it is still complaining:

2022-12-14 15:16:49.165 - [ERROR] callbacks.on_experiment_error(226): Simulation error: Could not find consistent states: Could not find acceptable solution: .../casadi/core/linsol.cpp:173: Assertion "m->is_nfact" failed:

Are there any other parameters in Prada2013 that I need to modify?

[brosaplanella]

Is it crashing at the very beginning? It seems that you start with a fully charged battery but the first step is charging. Could be related to that.

[skywo1f]

That wasn't an issue when it was only 1 battery

[skywo1f]

sorry I also forgot to show the solve line:
sim.solve([0, 3600],initial_soc=0) # solve for 1 hour

[skywo1f]

If I change the experiment and solution to:

exp = pybamm.Experiment(
    [
        (
#            "Charge at 1 C until 58.4 V",
#            "Hold at 58.4V until C/10",
            "Rest for 5 minutes",
            "Discharge at 0.01 C until 40 V",
            "Rest for 5 minutes",
        )
    ]
    )
sim.solve([0, 3600])  # solve for 1 hour

Then it complains:
2022-12-15 07:22:16.631 - [ERROR] callbacks.on_experiment_error(226): Simulation error: Events ['Maximum voltage'] are non-positive at initial conditions
Traceback (most recent call last):
File "lfp_sag16.py", line 40, in
sim.solve([0, 3600]) # solve for 1 hour
File "/home/iviti/.local/lib/python3.8/site-packages/pybamm/simulation.py", line 746, in solve
raise error
File "/home/iviti/.local/lib/python3.8/site-packages/pybamm/simulation.py", line 724, in solve
step_solution = solver.step(
File "/home/iviti/.local/lib/python3.8/site-packages/pybamm/solvers/base_solver.py", line 1184, in step
self._check_events_with_initial_conditions(t_eval, model, ext_and_inputs)
File "/home/iviti/.local/lib/python3.8/site-packages/pybamm/solvers/base_solver.py", line 1063, in _check_events_with_initial_conditions
raise pybamm.SolverError(
pybamm.expression_tree.exceptions.SolverError: Events ['Maximum voltage'] are non-positive at initial conditions

[skywo1f]

it is odd, but

exp = pybamm.Experiment(
    [
        (
#            "Charge at 1 C until 58.4 V",
#            "Hold at 58.4V until C/10",
            "Rest for 5 minutes",
            "Discharge at 0.01 C until 40 V",
            "Rest for 5 minutes",
        )
    ]
    )
sim.solve([0, 3600],initial_soc=1)  # solve for 1 hour 

seems to work

[skywo1f]

another odd thing is that if I do:

solution = sim.solution
A1 = solution["Current [A]"]
t1 = solution["Time [s]"]
V1 = solution["Terminal voltage [V]"]

I get ranges in the 2.5-3.65 V, instead of the expected 40-58.4V range (for V1.entries)

I will start a new discussion thread for this line of questions

[valentinsulzer]

The variable to use here is "Battery voltage [V]"

[skywo1f]

Another odd thing, this doesnt seem to work for Mohtat2020. There I set similar conditions:

exp = pybamm.Experiment(
    [
        (
            "Rest for 5 minutes",
            "Discharge at 0.01 C until 43.4 V",
            "Rest for 5 minutes",
        )
    ]
    )
model = pybamm.lithium_ion.SPM()
sim = pybamm.Simulation(model,experiment=exp,parameter_values=param)
sim.solve([0, 3600],initial_soc=1)  # solve for 1 hour

and

  "Number of cells connected in series to make a battery": 14.0,
        "Lower voltage cut-off [V]": 43.4,
        "Upper voltage cut-off [V]": 58.8,

but it tells me:
ValueError: The upper bound of the voltage, 5.2539V, is less than the target maximum voltage, 58.8000V. Stoichiometry limits are x:[0.0000, 0.8659], y:[0.0000, 0.8925].

[valentinsulzer]

Voltage cut-offs are at the single cell level, not battery