TY JOUR TI MATHEMATICAL MODELLING OF A LITHIUM-ION BATTERY IN STEADY-STATE CHARGE AND DISCHARGE MODES KW battery KW mathematical model KW validation KW Shepherd equation KW steady-state operating mode JO Automation and modeling in design and management AU Davoyan, G.Y. AU Sidorov, K.M. PY 2026 IS 2026 PB Bryansk State Technical University