SIMULATION OF TEMPERATURE-COMPENSATED VOLTAGE LIMIT CURVES FOR AEROSPACE NI-CD BATTERIES USING A FIRST PRINCIPLES 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 therma l runaway during overcharge. The voltage limits are experimentally det ermined from extensive testing of cells for a proper design of the cha rge control system to achieve the desired charge/discharge ratio in or bit. Here, we demonstrate the use of first-principles', mathematical m odels to construct the V/T curves theoretically. The predicted charge/ discharge ratios under various orbit conditions such as different stat es of charge, in-rush currents and temperatures are compared with the experimental data.