Battery charger

• US 6,225,786 B1
• Filed: 03/16/2000
• Issued: 05/01/2001
• Est. Priority Date: 03/25/1999
• Status: Expired due to Term

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Sakakibara, Kazuyuki, Muramatsu, Tomoo
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/527,126
• Time in Patent Office: 411 Days
• Field of Search: 320/116, 320/119, 320/124, 320/125, 320/127, 320/128, 320/137, 320/144, 320/150, 320/151, 320/152, 320/153
• US Class Current: 320/150
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A map is retrieved based on a battery temperature, a temperature rise value and an allowable current value, with which a battery can be charged while battery temperature rise is being suppressed, is obtained and the battery is charged with the allowable current value. By doing so, it is possible to charge a nickel metal hydride battery cell which temperature tends to rise during battery charge in a short time without causing deterioration due to temperature rise. This battery charger makes determinations after dividing the battery. Due to this, compared with a case of simultaneously determining all battery cells, it is possible to accurately determine the completion of charge.

Claims

1. A battery charger dividing and charging a battery consisting of a plurality of battery cells, characterized by comprising:

a storage device storing a map, in which an allowable current value, with which the battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value;

a temperature detecting section for detecting a present battery temperature;

a temperature rise value outputting section for obtaining the temperature rise value from the temperature detected by said temperature detecting section;

an allowable current value retrieving section for retrieving the map of said storage device based on the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section, and for obtaining said allowable current value;

a charging section for charging said divided battery with the allowable current value retrieved by said allowable current value retrieving section; and

a charge switching section for alternately switching divided blocks to be charged by said charging section.

2. A battery charger dividing a battery consisting of a plurality of battery cells into two or more blocks and charging the divided blocks, characterized by comprising:

a storage device storing a map, in which an allowable current value, with which the battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value, the allowable current value set at a low value if the battery temperature value is high and set at a low value if the temperature rise value is high;

a temperature detecting section for detecting a present battery temperature;

a temperature rise value outputting section for obtaining the temperature rise value from the temperature detected by said temperature detecting section;

an allowable current value retrieving section for retrieving the map of said storage device based on the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section, and for obtaining said allowable current value;

a charging section for charging said divided battery blocks with the allowable current value retrieved by said allowable current value retrieving section;

a charge switching section for alternately switching the divided battery blocks to be charged by said charge section;

a charge completion determining section for determining completion of charge of each of the divided battery blocks based on whether frequency, with which the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section belong to regions indicating a final charging period in the map of said storage device, is high; and

a charge completing section for completing charge of the divided battery blocks based on determination of completion of battery charge by said charge completion determining section.

3. A battery charger capable of simultaneously a battery consisting of a plurality of battery cells and dividing the battery into two or more blocks and then charging the divided battery blocks, characterized by comprising:

a storage device storing a map, in which an allowable current value, with which the battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value;

a temperature detecting section for detecting a present battery temperature;

a temperature rise value outputting section for obtaining the temperature rise value from the temperature detected by said temperature detecting section;

an allowable current value retrieving section for retrieving the map of said storage device based on the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section, and for obtaining said allowable current value;

a charging section for charging the battery with the allowable current value retrieved by said allowable current value retrieving section; and

a charge switching section for switching said charging section and charging the battery consisting of the plurality of battery cells simultaneously or charging the battery separately, wherein

said charge switching section simultaneously charges the battery consisting of the plurality of battery cells at beginning of battery charge, and alternately switches the divided battery blocks and charges the divided battery blocks in a final charging period.

4. A battery charger dividing a battery consisting of a plurality of cells into two or more blocks and charging the divided battery blocks, characterized by comprising:

a storage device storing a map, in which an allowable current value, with which the battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value, the allowable current value set at a low value if the battery temperature value is high and set at a low value if the temperature rise value is high;

a temperature detecting section for detecting a present battery temperature;

a temperature rise value outputting section for obtaining the temperature rise value from the temperature detected by said temperature detecting section;

an allowable current value retrieving section for retrieving the map of said storage device based on the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section, and for obtaining said allowable current value;

a charge switching section for switching said charging section and charging the battery consisting of the plurality of battery cells simultaneously or charging the battery separately;

a final charging period determining section for determining that a battery charge period is in a final charging period based on whether or not frequency, with which the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section belong to regions indicating the final charging period in the map of said storage section, is high; and

a charge completion determining section for determining completion of charge of each of the divided battery blocks based on whether or not the frequency, with which the temperature detected by said temperature detecting section and the temperature rise value outputted from said temperature rise value outputting section belong to the regions indicating the final charging period in the map of said storage section, is high, wherein

said charge switching section simultaneously charges the battery consisting of the plurality of battery cells at beginning of battery charge and, if the battery charge period is determined to be in the final charging period by said final charging period determining section, alternately switches the battery divided by the charge switching section and charges the battery until said charge completion determining section determines the completion of charge.