Seeking Guidance on Estimating State of Health (SoH) Calculation

[kimo707]

Hi All,

I'm currently working on estimating the State of Health (SoH) in PyBaMM, and I'm seeking some guidance on the calculation process. I have the nominal capacity and various outputs from the model, such as Total Lithium Capacity [A.h] and Total Lithium Lost [mol].

To calculate SoH, I've implemented two methods, and I'd appreciate your expertise in determining their correctness or if there's a better approach. Here are the methods I've used:

Method 1:

nominal_capacity = np.array(sim.solution["Total lithium capacity [A.h]"].entries)[0]
total_lithium_lost = np.array(sim.solution["Total lithium lost [mol]"].entries * 96485.3 / 3600)
current_capacity = nominal_capacity - total_lithium_lost
soh_percentage_1 = (current_capacity / nominal_capacity) * 100

Method 2:

nominal_capacity = 51 # Ah this from Battery info
total_lithium_lost = np.array(sim.solution["Total lithium lost [mol]"].entries * 96485.3 / 3600)
current_capacity = nominal_capacity - total_lithium_lost
soh_percentage_2 = (current_capacity / nominal_capacity) * 100

I'm uncertain which method is more accurate or if there's an alternative approach. Additionally, I'm interested in exploring other outputs like "Loss of Lithium Inventory [%]" and understanding how it differs from "Total Lithium Capacity [A.h]". Any insights or suggestions you could provide would be immensely helpful.

Thank you in advance for your time and assistance.