Publisher Summary Constant-current charging is suitable when the discharged ampere hours taken out in the previous discharge cycle are known. It is necessary to monitor battery voltage or manually cut off the current at the end of charge to ensure a good service life for the battery. This type of charging requires regulation by means of an automatic timer. A normal recharge time of 20 h is recommended, whereby the constant-current charging rate is established to give an input of 110% of the previous output. There are many constant-current methods that permit satisfactory charging of sealed nickel-cadmium batteries. These methods differ in the length of time required to charge, the complexity of the circuits used and the various techniques for charging with maximum safety and reliability. Numerous charging systems mentioned are: normal rate charge, accelerated charge, and permanent or floating charge. In addition, two-step constant-current charging and constant-current charger designs for normal-rate charging is explained.