Pass/fail battery indicator

Abstract

A battery tester, includes a voltage controlled display. The battery tester is disposed on a battery with a first voltage divider having a terminal coupled to a terminal of the voltage controlled display and a second voltage divider having a terminal coupled to a second terminal of the voltage controlled display. The second voltage divider includes a non-linear device. A major advantage of the tester compared to other testers is that a consumer can merely look at the tester on the battery to determine whether the battery is good or not. This tester eliminates the need to hold the battery and depress a switch to engage the battery tester.

What is claimed is:  
     
         1 . A battery tester, comprises: 
 a voltage controlled display;    a voltage divider having a terminal coupled to a terminal of the voltage controlled display; and    a non-linear device coupled to the voltage divider and a second terminal of the voltage controlled display.    
     
     
         2 . The battery tester of  claim 1  wherein the display is an electrophoretic display.  
     
     
         3 . The battery tester of  claim 1  wherein the non-linear device is a metal-insulator-metal diode.  
     
     
         4 . The battery tester of  claim 1  wherein the voltage divider includes a pair of resistors having the same resistance.  
     
     
         5 . The battery tester of  claim 1  further comprising a resistor and wherein the resistor is coupled in series with the non-linear device.  
     
     
         6 . The battery tester of  claim 1  wherein the tester in operation is always coupled to the battery.  
     
     
         7 . The battery tester of  claim 1  wherein a voltage potential at the first terminal of the display is a fraction of a battery cell voltage and a potential at the second terminal of the display is determined by a voltage across the non-linear element and resistor.  
     
     
         8 . The battery tester of  claim 7  wherein as current is drawn from a battery due to use or leakage, the voltage of one of the terminals of the display will vary with respect to the voltage at the other terminal of the display.  
     
     
         9 . The battery tester of  claim 8  wherein the non-linear device will switch states causing the voltage at one terminal of the display to become negative with respect to the voltage at the other terminal of the display to cause a change in color of the display to indicate that the battery is no longer within some defined specification.  
     
     
         10 . A battery comprising: 
 a cell having an outer circumference; and    a battery tester disposed on the outer circumference of the cell, said battery tester comprising: 
 a voltage controlled display;  
 a voltage divider having a terminal coupled to a terminal of the voltage controlled display; and  
 a circuit path coupled in parrallel with the voltage divider including a non-linear device and a resistor coupled in series wherein the non-linear device has a switching voltage characteristic that corresponds in magnitude to a voltage of the cell.  
   
     
     
         11 . The battery of  claim 10  wherein the display of the tester is an electrophoretic display.  
     
     
         12 . The battery of  claim 10  wherein the non-linear device of the tester is a metal-insulator-metal diode.  
     
     
         13 . The battery of  claim 10  wherein the voltage divider of the tester includes a pair of resistors having the same resistance.  
     
     
         14 . The battery of  claim 11  wherein the non-linear device of the tester is a metal-insulator-metal diode and the voltage divider of the tester includes a pair of resistors having the same resistance.  
     
     
         15 . The battery of  claim 10  wherein the tester is in continuous electrical contact with the cell.  
     
     
         16 . The battery of  claim 10  wherein a voltage potential at the first terminal of the display is some fraction of a battery cell voltage and a potential at the second terminal of the display is determined by voltage across the nonlinear element and resistor.  
     
     
         17 . The battery of  claim 16  wherein as current is drawn from a battery due to use or leakage, the voltage of one of the terminals of the display will vary with respect to the voltage at the other terminal of the display.  
     
     
         18 . The battery of  claim 17  wherein the non linear device will switch states causing the voltage at one of the terminal of the display to become negative with respect to the voltage at the other terminal of the display to cause a change in color of the display to indicate that the battery is no longer within some defined specification.