Method of charging a battery array

Abstract

The method of charging a battery array performs constant current and constant voltage charging of a battery array while detecting the voltage of each battery. The battery array is a plurality of series connected batteries. The charge method detects the voltage of each battery cell at a prescribed sampling rate. When the voltage of any battery cell exceeds a preset maximum specified voltage, charging power is reduced for constant current, constant voltage charging of the battery array.

1 - 20 . (canceled) 
     
     
         21 . A method of charging a battery array that performs constant current and constant voltage charging of a battery array, which is a plurality of series connected batteries, while detecting the voltage of each battery, the method comprising:
 detecting a voltage of each of a plurality of battery cells of a battery array at a prescribed sampling rate; and   performing a constant current and constant voltage charging of all the plurality of battery cells of the battery array at a same reduced charging power when a voltage of any battery cell of the battery array exceeds a maximum specified voltage.   
     
     
         22 . The method of  claim 21 , wherein the plurality of series connected batteries of the battery array are lithium ion rechargeable batteries. 
     
     
         23 . The method of  claim 21 , wherein the voltage of each battery cell of the battery array is detected at a prescribed sampling rate, and when the voltage of any battery cell exceeds a preset maximum specified voltage, a charging voltage is reduced for performing constant current and constant voltage charging of the battery array. 
     
     
         24 . The method of  claim 23 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, a voltage for charging the battery array is reduced by a prescribed ratio. 
     
     
         25 . The method of  claim 23 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced, and a ratio for reducing the charging voltage is determined from a voltage difference between the maximum specified voltage and a voltage of a battery cell, and when the voltage difference is large, the ratio for reducing the charging voltage is made large. 
     
     
         26 . The method of  claim 23 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced, and a ratio for reducing the charging voltage is determined from an internal resistance of a battery cell that exceeded a maximum specified voltage, and when battery cell internal resistance is large, the ratio for reducing the charging voltage is made large. 
     
     
         27 . The method of  claim 23 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced to a battery voltage, which is a sum of the voltages of each battery cell. 
     
     
         28 . The method of  claim 21 , wherein the voltage of each battery cell is detected at a prescribed sampling rate, when the voltage of any battery cell of the battery array exceeds a preset maximum specified voltage, a set current is reduced for performing constant current and constant voltage charging of the battery array. 
     
     
         29 . The method of  claim 28 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced by a prescribed ratio. 
     
     
         30 . The method of  claim 28 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced, and a ratio for reducing the set current is determined from a voltage difference between the maximum specified voltage and a voltage of the battery cell, and when the voltage difference is large, the ratio for reducing the set current is made large. 
     
     
         31 . The method of  claim 28 , wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced, and a ratio for reducing the set current is determined from an internal resistance of a battery cell that exceeded the maximum specified voltage, and when battery cell internal resistance is large, the ratio for reducing the set current is made large. 
     
     
         32 . The method of  claim 21 , wherein the maximum specified voltage is set in a range from 4.20V to 4.24V. 
     
     
         33 . The method of  claim 21 , wherein the maximum specified voltage changes with battery temperature. 
     
     
         34 . The method of  claim 33 , wherein a maximum specified voltage for battery charging in a low temperature region is set lower than a maximum specified voltage for battery charging in a standard temperature region. 
     
     
         35 . The method of  claim 34 , wherein the maximum specified voltage in the low temperature region is set from 30 mV to 300 mV lower than the maximum specified voltage in the standard temperature region. 
     
     
         36 . The method of  claim 33 , wherein a maximum specified voltage for battery charging in a high temperature region is set lower than a maximum specified voltage for battery charging in a standard temperature region. 
     
     
         37 . The method of  claim 33 , wherein a maximum specified voltage in a high temperature region is set lower than a maximum specified voltage in a standard temperature region, and is set higher than the maximum specified voltage in a low temperature region. 
     
     
         38 . The method of  claim 37 , wherein the maximum specified voltage in the high temperature region is set to make a voltage difference between the maximum specified voltage in the high temperature region and the maximum specified voltage in the standard temperature region 30% to 80% of a voltage difference between the maximum specified voltage in the low temperature region and the maximum specified voltage in the standard temperature region. 
     
     
         39 . The method of  claim 28 , wherein the set current changes with battery temperature. 
     
     
         40 . The method of  claim 39 , wherein reduction in set current is in accordance with multiple levels of a prescribed set current. 
     
     
         41 . The method of  claim 21 , wherein the charging power for charging the battery cells is reduced according to output from a difference amplifier which compares a reference voltage with the voltage of the battery cell. 
     
     
         42 . The method of  claim 41 ,
 wherein the difference amplifier comprises a positive-side difference amplifier to which a positive-side battery cell voltage is input, and a negative-side difference amplifier to which a negative-side battery cell voltage is input, and   wherein the charging power for charging the plurality of battery cells is reduced according to a signal issued by an OR circuit to which each output of the positive-side difference amplifier and the negative-side difference amplifier is input.