Minimum time defined in the experimental protocol

[optibikash]

Hi everyone!
The question is out of curiosity while experimenting with PyBaMM. In the pybamm.Experiment class, we define the time for which we wish to charge, discharge, or rest the battery. Is there a limitation to the definition of time?
Taking from the example script:
"Discharge at C/5 for 10 hours or until 3.3 V", "Rest for 1 hour", "Charge at 1 A until 4.1 V", "Hold at 4.1 V until 10 mA", "Rest for 1 hour",

Is it possible to define the time in milliseconds or microseconds? Do we have a limit for the definition of time?

[valentinsulzer]

Seconds is the smallest. But 1e-3 s should work (open an issue if it doesn't)

[optibikash]

Haven't heard back from you @tinosulzer . Can you suggest anything?

[valentinsulzer]

Please provide a complete code. The one line you gave is very generic and not enough information

[optibikash]

Sure @tinosulzer .This is one of the basic code
`
#Pulse Charging#

import csv
import pybamm
import numpy as np
import datetime

model = pybamm.lithium_ion.DFN(options = {"thermal": "lumped", "SEI":"reaction limited", "SEI porosity change" : "true", "lithium plating": "irreversible"})
parameter_values = pybamm.ParameterValues(chemistry=pybamm.parameter_sets.Chen2020_plating)
param = parameter_values
t1 = datetime.datetime.now()
f = open('completed.txt', 'w+')
f.write('Program execution started')
cycle = ["Discharge at C/30 until 2.8V"] + [
"Charge at 2C for 0.001 seconds", #Increase charge period
"Rest for 0.001 seconds"] * 225000 + ["Rest for 2 hours",
"Charge at C/30 until 4.2V", #Increase charge period
"Rest for 2 hours",
"Discharge at C/30 until 2.8V"]

experiment1 = pybamm.Experiment(cycle)

sim = pybamm.Simulation(model, experiment=experiment1, parameter_values=param)

sim.solve(solver=pybamm.CasadiSolver(mode="safe", dt_max=1000))
t2 = datetime.datetime.now()

sol = sim.solution

msg = "Program execution was completed at "+str(t1)+".\nTotal time elapsed\t"+str(t2-t1)+"."
f.write(msg)
f.close()
sol.save_data("Efficiency_500hz.csv", ["Time [s]", "Terminal voltage [V]" , "Current [A]","X-averaged cell temperature [K]"], to_format="csv")
sol.save_data("Efficiency_500hz.json", ["Time [s]", "Terminal voltage [V]" , "Current [A]","X-averaged cell temperature [K]"], to_format="json")
`

[koomarmdey]

Hey, I was looking into a similar project to simulate pulse charging using PyBaMM. Is it possible to this by defining small timesteps in my experiment? or is there any better way?

Any suggestions would be appreciated. Thanks

[optibikash]

@koomarmdey
I am not sure which version you are using, but I was using quite an old one. In the newer versions, I have not tried implementing pulse charging. You should have taken a look into the old comments, and you might have got the response. Quoting again what information was provided to me by @tinosulzer "Seconds is the smallest. But 1e-3 s should work (open an issue if it doesn't)."
Maybe with newer versions, it would have much smaller time steps compared to what it was 2 years back. The type of solver you select also plays a crucial role in the defining time steps. Since my code is already pasted in the previous comments, you know what I attempted and how. I hope this helps!