Patent ID: 8084989

Claim:
A battery charger comprising: a charging socket adapted to receive a charging signal; a damper unit including a pair of dampers; a rechargeable battery coupled to said clamper unit and adapted for providing electric power to an external rechargeable battery through said damper unit so as to charge the external rechargeable battery; a control unit coupled to said charging socket and said rechargeable battery and operable to charge said rechargeable battery through the charging signal received by said charging socket; and an alarm unit coupled to said rechargeable battery and said charging socket for generating a detecting signal based on a battery voltage of said rechargeable battery, for outputting a reminder output upon detecting that a potential of the detecting signal is less than that of a reference signal, and for terminating the reminder output when said charging socket receives the charging signal; wherein said charging socket includes a positive terminal coupled to said control unit and said alarm unit, a resilient negative terminal spaced apart from said positive terminal and coupled to at least one of said control unit and said damper unit, and a ground terminal spaced apart from said positive terminal, said charging socket being operable so as to switch from a non-charging state to a charging state when coupled with an external power plug that provides the charging signal, said negative terminal electrically contacting said ground terminal when said charging socket is at the non-charging state, said negative terminal being spaced apart from said ground terminal when said charging socket is at the charging state.