4V / 1.5 AH Rechargeable Battery for Arduino/Raspberry-Pi/Robotics

Charging at constant voltage is the most suitable and commonly used method for charging batteries. The charger voltage must be stabilized in a narrow range and with a device to suppress the initial current to less than 0.3C. The initial current limitation can be accomplished by a constant-current regulator, a properly designed output-voltage from the power transformer, or by designing the overall impedance of the circuit (such as using a current regulating resistor). During the final stage of charge, the current decreases automatically. Show constant voltage charger circuits provided with constant voltage functions, composed of transformers, transistors, silicon diodes, IC’s etc.

It is an effective method for supplementary charge of many batteries at one time in series during storage but the charging time must be strictly controlled. It is because if the charging is continued at the same rate for an extended period of time after the battery has reached a fully charged state, battery voltage rises excessively, water decomposes, heat generates, and a severe overcharge may occur resulting in a heavy damage to the battery. For longest life, it is not recommended to repeatedly use constant current charging for refreshing batteries