Method of charging a plurality of lithium ion rechargeable batteries

• US 5,808,442 A
• Filed: 09/27/1996
• Issued: 09/15/1998
• Est. Priority Date: 09/29/1995
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Kaite, Osamu, Okuyama, Toshiaki
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): SHIN, KYUNG E
• Application Number:
  US08/724,230
• Time in Patent Office: 718 Days
• Field of Search: 320/15, 320/16, 320/17, 320/6, 320/2, 320/39
• US Class Current: 320/125
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In the method of charging a plurality of lithium ion rechargeable batteries, if another battery is attached during battery charging, open circuit voltages of those respective batteries are measured and compared. When the open circuit voltage of the battery attached later is greater than that of the battery being charged, charging of the previously attached battery is suspended and the battery attached later is given priority and charged. When the open circuit voltage of the battery being charged is greater than that of the battery attached later, the battery being charged is given priority and charged.

Claims

1. A method of charging a plurality of lithium ion rechargeable batteries, which gives priority to charging batteries with a high amount of charge first, comprising the steps:

(1) when the amount of charge of any lithium ion rechargeable battery is greater than a reference charge, the battery with amount of charge greater than the reference charge is given priority and charged; and

(2) when the amounts of charge of all lithium ion rechargeable batteries are less than the reference charge or the amounts of charge of all lithium ion rechargeable batteries are greater than the reference charge, all batteries are connected in parallel and charged by constant current and constant voltage charging.

2. A method of charging a plurality of lithium ion rechargeable batteries as recited in claim 1 wherein when the amounts of charge of some, but not all, lithium ion rechargeable batteries are greater than the reference charge, batteries with amounts of charge greater than the reference charge are charged in a predetermined order.

3. A method of charging a plurality of lithium ion rechargeable batteries as recited in claim 2 wherein when the open circuit voltages of some, but not all, lithium ion rechargeable batteries are greater than 3.80 V/cell to 3.95 V/cell, those batteries are charged in a predetermined order.

4. A method of charging a plurality of lithium ion rechargeable batteries, which gives priority to charging batteries with a high amount of charge first, characterized by the steps:

(1) a plurality of lithium ion rechargeable batteries are charged to a specified amount of charge but charging is suspended prior to reaching full charge; and

(2) subsequently all batteries not fully charged are connected in parallel and simultaneously constant current and constant voltage charged to full charge.

5. A method of charging a plurality of lithium ion rechargeable batteries as recited in claim 4 wherein a plurality of lithium ion rechargeable batteries are charged until an open circuit voltage of 4.05 V/cell has been attained, and subsequently all batteries are connected in parallel and charged to full charge.

6. A method of charging a plurality of lithium ion rechargeable batteries, which gives priority to charging batteries with a high amount of charge first, comprising the steps of charging a plurality of lithium ion rechargeable batteries to a specified amount of charge but suspending charging prior to reaching full charge, subsequently connecting all batteries not fully charged in parallel, and simultaneously charging the batteries with constant current and constant voltage to full charge, wherein

(1) if another lithium ion rechargeable battery is attached while a lithium ion rechargeable battery is being charged, the amount of charge of the battery being charged and the amount of charge of the battery attached later are compared,

(2) when the amount of charge of the battery attached later is greater than that of the battery being charged, charging of the previously attached battery that was being charged is interrupted and the battery attached later is given priority and charged;

and

(3) when the amount of charge of the previously attached battery that was being charged is greater than that of the battery attached later, the previously attached battery that was being charged is given priority over the battery attached later and charged.

7. A method of charging a plurality of lithium ion rechargeable batteries as recited in claim 6 wherein a plurality of lithium ion rechargeable batteries are charged until an open circuit voltage of 4.05 V/cell has been attained, and subsequently all batteries are connected in parallel and charged to full charge.

8. A method of charging a plurality of lithium ion rechargeable batteries, which gives priority to charging batteries with a high amount of charge first, comprising the steps of measuring the amounts of charge of a plurality of lithium ion rechargeable batteries, comparing the amounts of charge with a reference charge, dividing the batteries into a group with amount of charge greater than the reference charge and a group with amount of charge less than the reference charge, charging batteries of the group with amount of charge greater than the reference charge to full charge in a predetermined order, and subsequently charging batteries of the group with amount of charge less than the reference charge to full charge in a predetermined order, wherein

(1) if another lithium ion rechargeable battery is attached while a lithium ion rechargeable battery is being charged, the amount of charge of the battery being charged and the amount of charge of the battery attached later are compared,

(2) when the amount of charge of the battery attached later is greater than that of the battery being charged, charging of the previously attached battery that was being charged is interrupted and the battery attached later is given priority and charged;

and

(3) when the amount of charge of the previously attached battery that was being charged is greater than that of the battery attached later, the previously attached battery that was being charged is given priority over the battery attached later and charged.

9. A method of charging a plurality of lithium ion rechargeable batteries as recited in claim 8 wherein the reference charge is an amount of charge corresponding to an open circuit battery voltage of 3.80 V/cell to 3.95 V/cell.