Simulation of temperature-compensated voltage limit curves for aerospace Ni---Cd batteries using a first principlesʹ model

Temperature-compensated voltage limits (V/T limits) are routinely used in Low Earth Orbit (LEO) satellites to permit fast charging of the Ni---Cd battery with minimum overcharge and without the problems of thermal runaway during overcharge. The voltage limits are experimentally determined from extensive testing of cells for a proper design of the charge control system to achieve the desired charge/discharge ratio in orbit. Here, we demonstrate the use of first-principlesʹ, mathematical models to construct the V/T curves theoretically. The predicted charge/discharge ratios under various orbit conditions such as different states of charge, in-rush currents and temperatures are compared with the experimental data.