Battery charge control device having function to decide gassing without temperature sensor

• US 6,246,216 B1
• Filed: 07/03/2000
• Issued: 06/12/2001
• Est. Priority Date: 07/02/1999
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Takemoto, Hisashi, Satake, Syuji
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/609,411
• Time in Patent Office: 344 Days
• Field of Search: 320/147, 320/137, 320/1, 429/96, 429/97, 429/98, 429/99
• US Class Current: 320/147
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• 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: H02J 7/00719 in response to degree of gas development in the battery

Abstract

A battery charge control device is capable of detecting a gassing state in a battery without using a temperature sensor. Under condition of charging the battery 5 with a charging current, when a terminal voltage Vi of the battery 5 monitored by the device exceeds a threshold value, a temporary-gassing detecting unit 23 informs a voltage regulation calculating unit 24 that the battery 5 is in course of reaching its gassing state. The voltage regulation calculating unit 24 calculates a changing rate of terminal voltage Vi of the battery 5 while it is in course of reaching the gassing state. When the calculated changing rate exceeds a preset decision value, a gassing detecting unit 25 judges that the battery 5 has just reached the gassing state. A decision value renewing unit 27 changes the decision value corresponding to the charging current.

Claims

1. A battery charge control device for controlling to charge a battery electrically connected with a load, the battery charge control device being constructed so as to charge the battery while lowering a charging current brought from the load in a step manner when the battery'"'"'s residual capacity drops during the load'"'"'s operation, the capacity measuring device comprising:

a memory unit for collecting and storing a sequential data of terminal voltage of the battery;

a temporary-gassing detecting unit connected to the memory unit, the temporary-gassing detecting unit generating a signal representing that the battery is in course of reaching its gassing state when the so-collected terminal voltage of the battery exceeds a threshold value during charging the battery with a charging current;

a voltage regulation calculating unit connected to the temporary gassing detecting unit so as to input the signal therefrom, the voltage regulation calculating unit calculating a changing rate of terminal voltage of the battery while the battery is in course of reaching the gassing state; and

a gassing detecting unit connected to the voltage regulation calculating unit, for judging that the battery has just reached the gassing state when the calculated changing rate exceeds a preset decision value for the changing rate.

2. A battery charge control device as claimed in claim 1, further comprising:

a charging current switching unit which allows the battery to be charged with a designated charging current corresponding to the beginning of charging and further switches the designated charging current to a next lower charging current as soon as the gassing state of the battery has been detected.

3. A battery charge control device as claimed in claim 2, further comprising:

a decision value renewing unit that, whenever the charging current is switched, changes the preset decision value for the changing rate to a new decision value for the changing rate of the voltage corresponding to the so-switched charging current.

4. A battery charge control device as claimed in claim 3, wherein the decision value is previously stored in another memory unit, corresponding to each of the charging currents and each of the stages of switching.

5. A battery charge control device as claimed in claim 1, wherein the threshold value is identical to one of terminal voltages predetermined on the ground of the temperatures of the battery and the charging currents at the initial stage of the charging.

6. A battery charge control device as claimed in claim 2, wherein the load comprises:

an alternator; and

a converter which converts a discharge power from the battery into a designated voltage thereby to transmit it to the alternator and which also converts a regenerative power from the alternator into the charging current of a current value switched by the charging current switching unit thereby to charge the battery.