Apparatus and method for charging and testing batteries

• US 4,876,495 A
• Filed: 06/27/1988
• Issued: 10/24/1989
• Est. Priority Date: 06/27/1988
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Mendelson, Stuart E., Palanisamy, Thirumalai G.
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US07/211,609
• Time in Patent Office: 484 Days
• Field of Search: 320/20, 320/21, 320/22-24, 320/17, 320/18
• US Class Current: 320/106
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

This invention relates to a method for charging a rechargeable battery especially lead-acid batteries. In this method, the open circuit voltage of the battery is measured and the minimum number of cells is estimated from this value. The battery is then charged at any charge rate and at a constant current until the battery voltage is substantially equal to the estimated number of cells multiplied by a voltage which is characteristic of the battery, and thereafter the battery is charged at any charge rate and at the aforesaid battery voltage until the current decreases to some predetermined value. The foregoing steps are repeated alternatively until a constant or substantially constant value for the estimate number of cells is obtained. Thereafter, the battery is charged at a voltage equal to the number of cells multiplied by the characteristic voltage of the battery until the current reaches a predetermined value and then the battery is charged at some predetermined current for a predetermined period of time.

Claims

1. A method for charging a rechargeable battery which comprises the steps of:

(a) measuring the open circuit voltage of said battery and estimating the minimum number of cells possible for the measured open circuit voltage;

(b) charging said battery at any charge rate and at a substantially constant or constant current until the battery charge voltage equals or is substantially equal to the estimated number of cells of the battery multiplied by a predetermined voltage which is characteristic of the battery;

(c) charging said battery at a charge rate and at a constant or substantially constant voltage equal to or substantially equal to the battery charge voltage in step (b) until the charge current decreases to a predetermined low value;

(d) repeating steps (a), (b) and (c) until step (a) indicates a constant or substantially constant value for the estimated number of cells;

(e) charging said battery at a constant or substantially constant voltage equal to or substantially equal to said constant or substantially constant value of step (d) times a voltage which is characteristic of the battery cells until the current decreases to zero or a predetermined low value; and

(f) charging the said battery with a predetermined constant or substantially constant current at any voltage for a predetermined period of time.

2. A method according to claim 1 wherein said battery is a lead-acid battery.

3. A method according to claim 1 which further comprises determining the state of charge of the battery from the measured open circuit voltage of said battery.

4. A method according to claim 1 which further comprises determining the presence of fault conditions from the measured open circuit voltage of said battery.