Method and unit for computing charging efficiency and charged electrical quantity of battery

• US 6,696,818 B2
• Filed: 10/03/2002
• Issued: 02/24/2004
• Est. Priority Date: 10/04/2001
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Arai, Youichi, Satake, Shuji
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US10/262,889
• Publication Number:
  US 20030067282A1
• Time in Patent Office: 509 Days
• Field of Search: 324/426, 324/430, 324/432, 324/433, 320/132, 320/149
• US Class Current: 320/132
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

A charging efficiency, which is a ratio of an electrical quantity charged in a battery as an electromotive force to a total electrical quantity supplied to the battery, is computed at a plurality of measuring points between a start and an end of charging of the battery. A resistance difference of the battery between a resistance at the charge start point and a resistance at one of the measuring points is obtained, and a full charged state resistance is obtained at a full charged state of the battery. By using a ratio of the resistance difference to the full charged state resistance, a charging efficiency of the battery is computed at the one of the measuring points. The battery is in an active state where no passivating film is formed on poles of the battery. A charged electrical quantity of the battery is obtained based on the charging efficiencies sequentially obtained during the charging of the battery when the battery is in the active state. In the mean time, a charged electrical quantity of the battery is obtained based on an integration of a charging current multiplied by a corresponding charging time during a transition period in which a passivating film remains on the poles of the battery before the charging current sufficiently breaks the passivating film.

Claims

1. A method for computing a charging efficiency, which is a ratio of an electrical quantity charged in a battery as an electromotive force to a total electrical quantity supplied to the battery, at any one point in time between a start and an end of charging of the battery, the method comprising:

measuring an initial resistance of the battery at the start of the charging,

measuring a voltage and a current between a pair of terminals of the battery at the one point to obtain an inner resistance of the battery at the one point,

obtaining a resistance difference which is a difference of the inner resistance at the one point and the initial resistance, and

obtaining a ratio of the resistance difference to a full charged state resistance that is a resistance of the battery at a full charged state of the battery,

whereby, a charging efficiency of the battery at the one point is computed based on the ratio.

2. A method for computing a charging efficiency according to claim 1 wherein the ratio of the resistance difference to the full charged state resistance is deducted from 1 (one) to provide a charging efficiency at the one point.

3. A method for computing a charged electrical quantity of the battery according to claim 1, wherein a charged electrical quantity stored in the battery at the charging end of the battery is obtained by using a plurality of the charging efficiencies each obtained at each of a plurality of the measuring points in time between the start and the end of charging of the battery.

4. A method for computing a charged electrical quantity according to claim 1, wherein the battery has poles that are in an active state where no passivating film is formed on the poles, and whether the poles are in the active state is determined based on a pattern of the charging current varying with time during the charging,

the charged electrical quantity charged in the battery being obtained by using a plurality of the charging efficiencies each obtained at each of a plurality of the measuring points in time between the start and the end of charging of the battery when the poles are in the active state,

the charged electrical quantity of the battery being obtained based on an integration of a charging current multiplied by a corresponding charging time during a transition period in which a passivating film remains on the poles of the battery before the charging current sufficiently breaks the passivating film.

5. A unit for computing a charging efficiency, which is a ratio of an electrical quantity charged in a battery as an electromotive force to a total electrical quantity supplied to the battery, at any one point in time between a start and an end of charging of the battery, the unit comprising:

a measuring device for measuring a voltage and a current between a pair of terminals of the battery at the one point to obtain an inner resistance of the battery at the one point,

an initial resistance computing device for obtaining an inner resistance of the battery at the charging start based on a terminal voltage and the corresponding current which are measured by the measuring device,

an on-charging resistance computing device for obtaining an inner resistance of the battery at the one point based on a terminal voltage and a corresponding current which are measured by the measuring device,

a resistance difference computing device for obtaining a difference between of the inner resistance at the one point and the initial resistance,

a storage device for storing an inner resistance at a full charged state of the battery, and

a resistance ratio computing device for obtaining a ratio of the resistance difference to the full charged state resistance,

whereby, a charging efficiency of the battery at the one point is computed based on the ratio.

6. A unit for computing a charging efficiency according to claim 5 wherein the resistance ratio computing device deducts the ratio of the resistance difference to the full charged state resistance from 1 (one) to provide a charging efficiency of the battery at the one point.

7. A unit for computing a charged electrical quantity according to claim 5, wherein a charged electrical quantity stored in the battery at the charging end of the battery is obtained by using a plurality of charging efficiencies each obtained at each of a plurality of sequential points in time between the start and the end of charging of the battery by means of the charging efficiency computing unit.

8. A unit for computing a charged electrical quantity according to claim 5, wherein the battery has poles that are in an active state where no passivating film is formed on the poles, and the charged electrical quantity computing unit further comprises:

an active state determining device for determining whether the poles are in the active state based on a pattern of the charging current varying with time during the charging, the charging current obtained by the measuring device,

the charged electrical quantity charged in the battery being obtained by using a plurality of charging efficiencies each obtained at each of a plurality of sequential points in time between the start and the end of charging of the battery when the poles are in the active state, and

a charged electrical quantity computing device for obtaining a charged electrical quantity during a transition period in which a passivating film remains on the poles of the battery so that the poles are not in the active state before the charging current sufficiently breaks the passivating film, the charged electrical quantity of the battery being obtained based on an integration of a charging current multiplied by a corresponding charging time during the transition period.