Patent ID: 6181107
Filing Date: 2001-01-30
Classification: H01M,H02J,Y02E

Abstract:
A recharger (400) for recharging an Li-ion (lithium ion) secondary battery pack comprising:(a) a recharging power supplying circuit (420) connected to recharging terminals of a battery case, for supplying recharging power;(b) a recharging voltage measuring circuit (430);(c) a recharging control circuit (440) for controlling said recharging power supplying circuit (420) based upon a measured voltage measured by said recharging voltage measuring circuit (430); wherein:a recharging operation is classified into a first process operation (from S101 to S103) and a second process operation (from S104 to S109); said first process operation (from S101 to S103) is performed until an output voltage of said recharging power supplying circuit (420) becomes a constant voltage; and, said second process operation (from S104 to S109) is performed until a voltage of said Li-ion secondary battery pack becomes its full recharging voltage; wherein said first process operation comprises a first step (S101), second step (S102) and a third step (S103); andin said first step (S101), said recharging control circuit (440) commences said charging operation at a constant current issued from said recharging power supplying circuit (420);in said second step (S102), said recharging voltage measuring circuit (430) measures said output voltage of said recharging power supplying circuit (420);in said third step (S103), said recharging control circuit (440) judges as to whether or not the thus measured output voltage of said recharging power supplying circuit (420) is higher than, or equal to said constant voltage; said third step (S103) is followed by said first step (S101) when the thus measured output voltage of said recharging power supplying circuit (420) does not reach said constant voltage; said third step (S103) is followed by a fourth step (S104) of said second process operation (from S104 to S109) when the thus measured output voltage of said recharging power supplying circuit (420) is higher than, or equal to said constant voltage, so that said first process operation (from S101 to S103) is completed and followed by said second process operation (from S104 to S109); the improvement wherein:said fourth step (104) of said second process operation (from S104 to S109), rechargaing, is temporarily stopped, said fourth step (104) being followed by a fifth step (S105);in said fifth step (S105), said recharging control circuit (440) causes said recharging voltage measuring circuit (430) to measure a recharging voltage of said secondary battery pack, said fifth step (S105) bein followed by a sixth step (S106);in said sixth step (S106), said recharging control circuit (440) judges as to whether or not the thus measured voltage of said secondary battery pack is equal to said full recharging voltage, raid sixth step (S106) being followed by a seventh step (S107);in said seventh step (S107), said recharging control circuit (440) controls said recharging power supplying circuit (420) in such a manner that said output voltage of said recharging power supplying circuit (420) becomes slightly higher than said constant voltage to form a first slightly higher output voltage, said seventh step (S107) being followed by an eight step (S108);in said eighth step (S108), said first slightly higher output voltage is applied from said recharging power supplying circuit (420) to said Li-ion secondary battery, said eighth step (S108) being followed by a ninth step (S109);in said ninth step (S109), said first slightly higher output voltage is applied for a predetermined time; andin said ninth step (S109) of said second process operation (from S104 to S109) is followed by said fourth step (S104) of said second process operation (from S104 to S109) to complete a first cycle of said second process operation, said first cycle being followed by a second cycle of said second process operation (from S104 to S109), said second cycle being followed by a subsequent cycle, said subsequent cycle being followed by a further subsequent cycle, and so on until the recharging voltage of said Li-ion secondary battery reaches its full recharging voltage;wherein said slightly higher output voltages intermittently applied to said Li-ion secondary battery are gradually increased in magnitude to effectively shorten a recharging period of time for said Li-ion secondary battery.