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.

Abstract: An intrinsically safe battery pack arrangement for electrically powering electrical devices is disclosed. The power pack has a device for electronically determining a short in a cable or device and switching off the voltage to the power pack. The electronic device includes a transisterized circuit for sensing and controlling current through the cable. When the current exceeds a predetermined maximum, the circuit limits the current in the cable to a maximum value. The circuit is latched in the off position when the short is present for an extended time and the circuit may be reset after the short is removed and the problem corrected. This form of circuitry in power packs for use with mining equipment such as lamps, provides a unit which will not cause hazardous sparks when shorted thereby constituting an intrinsically safe device for use in mines.

Abstract: A lamp rechargeable dry cell power pack and recharging device therefor is disclosed. The recharging device comprises a socket for receiving the power pack, a plurality of electrodes are presented in the socket and arranged to contact corresponding electrodes on the power pack when it is fully inserted in the socket. The power pack is irregular shaped in cross-section and the socket is correspondingly shaped to receive and support the power pack in only one orientation of the power pack relative to the socket to ensure the registration of the plurality of socket electrodes with corresponding power pack electrodes.