When charging rechargeable batteries, there are various charging methods adapted to the corresponding batteries with their chemical conversions, which ensure gentle charging. The charging procedure is sufficiently characterized by the time control of the charging current and the charging voltage.
In order not to impair the service life of the battery, the charging process must exclude risks of too rapid charging as well as overcharging and undercharging. The various charging methods are implemented in the chargers and adapted to the battery types accordingly. It is crucial that the charging current and voltage are controlled in such a way that the accumulator is not damaged. This also includes cut-off mechanisms that protect the accumulators from damage caused by overcharging or by excessively high accumulator temperatures.
There are several voltage-, current- and time-controlled charging methods. These include the constant voltage charging method, the constant current charging method and its pulsed variant, the pulse charging method, the IU charging method and the reverse current charging method. As for the cut-off mechanisms, the battery charge can be cut off when the maximum charge voltage is reached, it can be cut off when the temperature exceeds a specified value, this is called temperature cut-off, or when a voltage drop occurs during full charge. This procedure is called minus-delta-U disconnection.