Charging device with multi-step voltage charging source

A charging device with a multi-step voltage charging source with means for taking active control over charging source voltage to further control its outputted charging current in the course of charging process executed by a (dis)chargeable storage discharging device so that when the charging from the (dis)chargeable storage discharging device arrives at a preset voltage, a primary control switch connected in series with a charging circuit is driven by the preset voltage to execute cutoff so to stop charging the (dis)chargeable storage discharging device.