Pulsed Discharge of a Lithium-Ion Cell in an Equivalent-Circuit Simulation: Effect of Peak Current and Pulse Period on Usable Capacity

Battery-powered cyber-physical devices often draw current in pulses, for example during radio transmission, and the effect of pulsing on the usable capacity is not obvious. This paper simulates a lithium-ion cell with a Thevenin equivalent circuit (nominal capacity 2.5 Ah, series resistance 60 mΩ, one RC branch with a time constant of 45 s) discharged to a 3.0 V cut-off with five current profiles. A constant 1 A load delivered 2.27 Ah, whereas pulsed loads with the same average current of 1 A (2 A at 50 % duty) delivered 2.17 Ah for a 10 s period and 2.16 Ah for a 120 s period. A 3 A / 33 % duty profile delivered 2.03 Ah. In the model, higher peak currents reach the voltage cut-off earlier because of larger resistive and polarisation voltage drops, leaving more charge unused. The cell parameters and the open-circuit-voltage curve are assumed, not measured. This is a simulation study; all results are outputs of the deposited Python code with assumed parameters. Source code is attached.