Method for fast charging of different types of batteries

• US 5,625,274 A
• Filed: 11/08/1995
• Issued: 04/29/1997
• Est. Priority Date: 11/11/1994
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Naskali, Matti
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Law, Patrick B.
• Application Number:
  US08/555,206
• Time in Patent Office: 538 Days
• Field of Search: 320/20, 320/21, 320/22, 320/23
• US Class Current: 320/149
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

The invention relates to a method for terminating the charging of a battery, in which a certain decrease in the battery voltage is detected when the battery is fully charged and the charge begins to decrease. With the invention it is possible to prevent battery overcharge reliably and efficiently. The solution can be applied to the charging of both Ni--Cd and Ni--MH batteries with a same charger and/or same charge control program.

Claims

1. A method for charging a battery wherein the charging of the battery voltage is terminated when the battery is fully charged and the voltage of the battery begins to decrease, comprising the steps of:

step 1, a voltage decrease -Δ

V of a battery;

step 2, measuring 9 length of the time during which the voltage decrease is detected,

step 3, integrating the detected voltage decrease -Δ

V over the measured length of time of step 2,

step 4, comparing the integrated detected voltage decrease of step 4 to a predetermined total value, and

step 5, terminating the charging of the battery when the integrated detected voltage decrease exceeds the predetermined total value.

2. The method of claim 1, characterized in that the predetermined total value to be detected is selected to equal the smallest possible voltage decrease -Δ

V that can be detected.

3. The method of claim 1, characterized in that, in addition, the integrating of step 3 is continued only for a predetermined observation period and if the integrating result does not reach said total value within the observation period, the integrating is stopped and will be started again from the beginning when a new predetermined decrease is detected (in step 1).

4. The method of claim 1, characterized in that the steps 1, 2, 3, 4, and 5 are applied for terminating the charging of different types of batteries.

5. The method of claim 4, characterized in that the steps 1, 2, 3, 4, and 5 are used to charge at least Ni--Cd and Ni--MH batteries with a same charger and same charge control program.

6. The method of claim 4, characterized in that the steps 1, 2, 3, 4, and 5 are used to charge at least Ni-Cd and Ni-MH batteries with a same charger.

7. The method of claim 4, characterized in that the steps 1, 2, 3, 4, and 5 are used to charge at least Ni--Cd and Ni--MH batteries with a same charge control program.

8. The method of claim 1 for charging and terminating the charging of batteries contained in mobile stations.