Abstract: An electronic battery charger for charging various types of dry cells including nickel-cadmium batteries provides for a cool down phase during battery charging cycle once a maximum predetermined temperature or voltage for the battery has been sensed. Subsequent to the cool down phase, a charging current is controlled in a manner such that, as battery temperature continues to decrease, a control device increases the charging current applied to the battery. Once a reheating of the battery is detected, the control device decreases the charging current. In this manner, a maximum charge is achieved in the battery at a temperature close to the ambient temperature.

Abstract: Method and apparatus is disclosed for measuring battery temperature and battery voltage during battery charging. The system is designed to charge a battery using two charging terminals and sensing battery voltage and temperature through the charging terminals. In measuring the temperature of the battery, the battery is electrically isolated from the sensing circuit during a portion of the charging cycle where the charging voltage is less than the battery voltage. Should the temperature of the battery, as measured, increase to a predetermined upper limit, the charging cycle is switched to a trickle charge on the battery. The battery voltage is measured at the instant when charging voltage exceeds the battery voltage to give a true indication of the recharged potential of the battery. When the sensed battery voltage is at the desired level, charging is switched to trickle charge.