Device for determining the state of charge in batteries

• US 3,969,667 A
• Filed: 12/20/1974
• Issued: 07/13/1976
• Est. Priority Date: 08/23/1972
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: McWilliams, Gerald E.
• Primary Examiner(s): Rolinec, R. V.
• Assistant Examiner(s): Tokar, Michael J.
• Application Number:
  US05/534,990
• Time in Patent Office: 571 Days
• Field of Search: 324/29.5, 324/62, 324/182, 324/133, 320/21, 320/29, 320/32, 320/39, 320/43, 320/48, 320/13, 320/9, 320/44
• US Class Current: 324/427
• CPC Class Codes: G01R 31/3646 for indicating electrical conditions or variables, e.g. visual or audible indicators
• CPC Class Codes: Y10S 320/21 State of charge of battery

Abstract

A device for determining the state of charge in batteries. The battery un test is discharged to its maximum capability by controlling the discharge current in a linear manner. The product of the current and battery voltage is recorded until the battery power reaches maximum at the maximum power point. The readings, peak power and the potential of the battery at the peak power, are held on meters by peak read and hold and track and hold circuits, respectively. From the readings obtained the state of charge can be determined by using a calibration curve for the type of battery being tested.

Claims

1. A device for determining the state of charge in an electrochemical system said system comprising in combination:

a. power measuring means connected to said electrochemical system having an output voltage proportional to the power output of said electrochemical system,

b. peak read and hold circuit means connected to said power measuring means and providing a first output that is proportional to the output voltage of said power measuring means and a second output that is proportional to the error signal of said peak read and hold circuit,

c. power indicating means connected to the first output of said peak read and hold circuit means,

d. a current control means coupled to said electrochemical system for controlling the current flow from said electrochemical system to increase in a linear manner;

e. a means for generating a ramp function signal coupled to said current control means for controlling said current control means in a linear manner.

f. track and hold circuit means coupled to said electrochemical system for providing an output voltage proportional to the output voltage of said electrochemical system,

g. voltage indicating means connected to the output of said track and hold circuit means,

h. first control means coupled between said current control means and said ramp function signal generating means and having an input connected to said second output of said peak read and hold circuit means for disconnecting said ramp function signal generating means from said current control means in response to a predetermined value of said error signal,

i. second control means coupled between said track and hold circuit means and said electrochemical system and having an input connected to said second output of said peak read and hold circuit means for disconnecting said track and hold circuit means for said electrochemical system in response to said predetermined value of said error signal.

2. A device for determining the state of charge in an electrochemical system said system comprising in combination:

a. first circuit means coupled to said electrochemical system for measuring and holding the power output of said electrochemical system,

b. second circuit means coupled to said electrochemical system for controlling the current flow from said electrochemical system to increase in a linear manner,

c. third means coupled to said electrochemical system for measuring and holding the voltage across the output of said electrochemical system,

d. fourth circuit means connected to said first and second circuit means for disconnecting said second circuit means from said electrochemical system in response to a sensed peak power signal,

e. fifth circuit means connected to said first and third circuit means for disconnecting said third circuit means from said electrochemical system in response to said sensed peak power signal,

f. first and second indicator means connected respectively to said first and third circuit means for indicating respectively the output power and output voltage of said electrochemical system when said fourth and fifth circuit means disconnect said second and third circuit means respectively from said electrochemical system.