Battery maintenance apparatus

• US 4,562,398 A
• Filed: 01/31/1984
• Issued: 12/31/1985
• Est. Priority Date: 06/08/1983
• Status: Expired due to Fees

• Current Assignee: Zarlink Semiconductor Inc. (Microchip Technology Incorporated)
• Original Assignee: Zarlink Semiconductor Inc. (Microchip Technology Incorporated)
• Inventors: Kotlarewsky, Paul
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Ault, Anita M.
• Application Number:
  US06/575,527
• Time in Patent Office: 700 Days
• Field of Search: 320/21, 320/31, 320/37, 320/38, 320/39, 320/40
• US Class Current: 320/157
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation

Abstract

A method and apparatus is disclosed for automatic control of battery maintenance including fast recharge and equalizing of the voltages on individual cells of the battery. The charging current through a resistance in series with the battery is monitored, and in response, a control circuit energizes a relay which controls the output voltage of a power supply used to charge the battery and drive a load. The control circuit includes a clock, connected to a recharge counter, which effects the recharge process for a predetermined period of time. The recharge counter is connected to the relay which regulates the output voltage of the power supply. The control circuit also includes a battery current sensor, which monitors the charging current of the battery, and a second counter, which provides an enabling signal to the relay for initiating a longer cycle which equalizes the charges on individual cells of the battery if the battery has been recharged from a severely discharge state.

Claims

1. A battery maintenance apparatus for maintaining charge in a battery connected across a source of battery charging current, comprising:

(a) means for monitoring a sum current comprised of battery drain current and float charging current of the battery;

(b) means for controlling repetitive recharging of the battery at a high charging rate for first predetermined time periods in the event the monitored sum current is greater than a predetermined level; and

(c) means for controlling recharging of the battery for a second predetermined time period which is much greater than any of the first predetermined time periods in the event the battery has been recharged a predetermined number of times for said predetermined first time periods.

2. A battery maintenance apparatus as defined in claim 1, in which said recharge controlling means includes means for causing continuation of the repetitive charging for said first predetermined time periods until the monitored sum current is less than said predetermined level.

3. A battery maintenance apparatus as defined in claim 2 further including means for initiating a first one of said first predetermined time periods after a first predetermined delay time period, and for causing successive ones of said first predetermined time periods to follow successive ones of said first predetermined delay time period.

4. A battery maintenance apparatus as defined in claim 2 further including means for causing said second predetermined time period to follow a predetermined second delay time period which follows a last one of said first predetermined time periods.

5. A battery maintenance apparatus as defined in claim 2, in which said recharge controlling means further includes means for causing said second predetermined time period to follow a last one of said first predetermined time periods.

6. A battery maintenance apparatus as defined in claim 5 further including means for initiating a first one of said first predetermined time periods after a first predetermined delay time period, and for causing successive ones of said first predetermined time periods to follow successive ones of said first predetermined delay time period.

7. A battery maintenance apparatus as defined in claim 5 further including means for causing said second predetermined time period to follow a predetermined second delay time period which follows a last one of said first predetermined time periods.

8. A battery maintenance apparatus as defined in claim 1 further including means for initiating a first one of said first predetermined time periods after a first predetermined delay time period, and for causing successive ones of said first predetermined time periods to follow successive ones of said first predetermined delay time period.

9. A battery maintenance apparatus as defined in claim 1 further including means for causing said second predetermined time period to follow a predetermined second delay time period which follows a last one of said first predetermined time periods.

10. A battery maintenance apparatus for maintaining charge in a battery, comprising:

(a) a source of battery charging current for said battery having a voltage control input for causing a high current battery charging rate if enabled and a lower current float charging rate if not enabled;

(b) resistance means for connection in series with said battery and a load; and

(c) a control circuit, including current sensing means connected to said resistance means for monitoring the sum of a float charging current and a drain current of the battery, for enabling said source of battery charging current for a first predetermined period of time, constituting a recharge cycle, in the event the float charging current is higher than a predetermined threshold, and for enabling said source of battery charging current to provide an equalize cycle for a second predetermined period of time significantly longer than the first predetermined period of time in the event a predetermined number of recharge cycles have occurred.

11. A battery maintenance apparatus as defined in claim 10 wherein said control circuit includes means for enabling said source of battery charging current for successive first predetermined periods of time, each constituting a recharge cycle, in the event the float charging current is higher than the predetermined threshold for a predetermined first delay time period, and wherein said source of battery charging current is enabled to provide said equalize cycle for the second predetermined period of time in the event no recharge cycle has occurred within a predetermined second delay time period and a predetermined number of consecutive recharge cycles has occurred.

12. A battery maintenance apparatus as defined in claim 11 in which the control circuit further includes a relay, and means for energizing the relay whereby a pair of contacts of the relay are operated to enable the source of battery charging current.

13. A battery maintenance apparatus as defined in claim 12 wherein the control circuit further includes:

(a) a switch means for providing a circuit path for energizing said relay, when enabled,

(b) clock means for providing a train of timing pulses,

(c) a first counter means connected to said current sensing means and said clock means for generating said predetermined first and second delay time periods, and for generating the first output signal for enabling said switch means for said first predetermined period of time in the event the float charging current is greater than said predetermined threshold for said predetermined first delay time period, and for generating a flag signal if said predetermined number of consecutive recharge cycles have occurred,

(d) memory means for storing said flag signal, and

(e) a second counter means connected to said memory means, said clock means, and the first counter means for generating a second output signal for enabling the switch means for said second predetermined period of time, and for disabling the first counter if no recharge cycle has occurred within said predetermined second delay time period and said flag signal is stored, and for generating a reset signal for resetting said memory means after said second predetermined time period.

14. A method for automatic control of battery maintenance comprised of:

(a) applying a nominal charging current to a battery,

(b) monitoring the sum of a float charging current and a drain current of the battery to determine if it is in excess of a predetermined threshold, indicating a discharged battery,

(c) providing a recharge cycle if the battery is discharged, consisting of charging the battery at a high voltage for a first predetermined period of time, and

(d) providing an equalize cycle for unifying the voltages on the individual cells if a predetermined number of recharge cycles have been performed, consisting of applying said high voltage to the battery for a period of time longer than that of the recharge cycle.

15. A method as defined in claim 14, in which the recharge cycle is repeated until the battery is fully charged, and in which the equalize cycle is performed by applying said high voltage to the battery following a last one of the recharge cycles for a second predetermined period of time which is longer than the first predetermined period of time.

16. A method for automatic control of battery maintenance as defined in claim 15, further including causing a first predetermined delay time period between successive repetitions of said recharge cycle.

17. A method for automatic control of battery maintenance as defined in claim 16, further including causing a second predetermined delay time period before said equalize cycle.