signal 28 the control and monitor module 20 monitors the feedback signal 28 to determine when to send a control signal 26 to the switching regulator 18 to change modes from current limiting to constant voltage this signal is preferably sent to the switching regulator 18 when the feedback signal 28 is around the threshold value the control and monitor module 20 then monitors the feedback signal 28 to ramp up the charger output 24 as the rechargeable battery 25 is charged to the final desired voltage level fully charged the switching regulator 18 thus produces an output signal 24 at a voltage that is higher than the voltage of the rechargeable battery 25 the charging continues until the rechargeable battery 25 is fully charged around 4 1 v or the charger battery voltage drops to 1 0 v if the charger battery voltage drops to 1 0 v then the control and monitor module 20 may send a signal to the mobile device 23 which can notify a user that the charger battery 11 is in a low voltage state and charging has stopped the control and monitor module 20 thus monitors the charge in both batteries to determine how to charge the rechargeable battery 25 from the charger battery 11 for example when a user determines that the rechargeable battery 25 in the mobile device.