Termination of nickel-cadmium battery charging process - by detecting terminal voltage peak which occurs when fully charged

摘要

The application is principally to fast charging of nickel cadmium cells for model or toy power supplies. In particular it is useful for batteries with sintered electrodes. To determine the fully charged state, use is made of the voltage peak coincident with a state of full charge which is a characteristic of the cell. The cell voltage is continuously monitored, and the charge switched off when the peak is detected. In a practical design the voltage is converted into a voltage dependant frequency and applied in successive equal time intervals to an up-down counter. If at the end of such a cycle the count is greater than zero the battery is assumed to be charged and the charger switched off. This monitoring method overcomes the strong temperature dependence of the voltage peak.