Temperature Behavior of Ni Cad Batteries and the Determination of their "State of Charge" States

A research task was undertaken to evaluate the behavior of Ni Cad batteries under extreme temperature conditions. Identical tests were repeatedly performed in order to record the spread of terminal voltages and discharge capacity during (a) initial conditions, (b) after several charge/discharge cycles, and (c) under different temperature conditions. The test proved that significant degradation of performance took place due to exposure to high and low temperatures and due to repeated charge/discharge cycles. Furthermore, it showed that the state of charge status cannot be extracted from the terminal voltages since the variations in this parameter were extremely large.