Resetable battery drain limitation circuit with complementary dual voltage setpoints

• US 6,066,899 A
• Filed: 07/30/1997
• Issued: 05/23/2000
• Est. Priority Date: 08/01/1996
• Status: Expired due to Fees

• Current Assignee: Power Technics Incorporated
• Original Assignee: Power Technics Incorporated
• Inventors: Rund, Larry D., Sigafoos, Stuart O., Hewitt, Richard P.
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US08/902,930
• Time in Patent Office: 1,028 Days
• Field of Search: 307/10.7, 307/10.6, 361/92, 340/636, 340/663, 320/132, 320/136
• US Class Current: 307/10.7
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

A battery drain limitation circuit for use in engine powered vehicles and equipment which rely upon a battery to start the engine and also to operate accessories. When the engine is not running, the circuit disconnects the battery from all loads when battery charge, as measured by either one of two complementary means responsive to high and low drain rates, respectively, falls to a level below which the battery charge may not be sufficient to start the engine. High drain rates exaggerate battery voltage reduction below no load voltage levels, and are detected by a low cutoff voltage level after which the battery voltage recovers to reflect sufficient charge to start the engine. Battery dissipation from low drain rates is prevented by a long timing delay following detection of a high cutoff voltage level. The circuit is rendered inoperable if the engine is running, by means of a microphone which detects engine noise. The device is simple to install at the battery.

Claims

1. In an engine powered vehicle or equipment having a battery operated electric starter motor and other electrical accessories, said battery having a threshold no load voltage level below which there may not be enough energy in said battery to operate said electric starter motor to start said engine, a battery drain limitation device, comprising:

a complementary dual voltage detection means for determining a low charge condition on said battery, said low charge condition being equivalent to a no load battery voltage at or below said threshold voltage level;

a second detection means for determining whether said engine is running;

interrupting means, responsive to said complementary dual voltage detection means and said second detection means, for disconnecting the flow of current from said battery when said low charge condition is detected and when said engine is not running, and

reset means for reconnecting the flow of current from said battery to said starter motor and said accessories.

2. The device of claim 1, wherein said complementary dual voltage detection means comprises a high drain detection means and a low drain detection means, said high drain detection means being operable to detect moderate to high drains and said low drain detection means being operable to detect low to moderate drains.

3. The device of claim 2, wherein said complementary dual voltage detection means includes means for setting a stable reference voltage.

4. The device of claim 3, wherein said high drain detection means comprises means for detecting a low voltage cutoff level and said low drain detection means comprises means for detecting a high voltage cutoff level and long timer means for delaying response of said interrupting means to said low drain detection means.

5. The device of claim 4, wherein said accessories include accessories normally operable when said engine is off, and wherein said high voltage cutoff level is set low enough so that under normal operating conditions of said vehicle or equipment said normally operable accessories will not cause said low drain detection means to be operable.

6. The device of claim 4, wherein said low voltage cutoff level is set so that if said battery reaches said low voltage cutoff level in response to discharge by a moderate to high drain source, there remains in said battery sufficient charge to operate said electric starter motor to start said engine, and wherein said high voltage cutoff level and said long delay timer are set so that if said battery reaches said high voltage cutoff level in response to discharge by a low to moderate drain source, when said long delay timer runs out there remains sufficient charge in said battery to operate said electric starter motor to start said engine.

7. The device of claim 6, wherein said long delay timer is reset when said battery is recharged above said high cutoff voltage level.

8. The device of claim 7, wherein said interrupting means includes short delay means for delaying battery disconnection long enough to start said engine.

9. The device of claim 8, wherein said high voltage cutoff level is set at a level which, under no load conditions, would indicate said battery retains about half its charge.

10. The device of claim 7, wherein said low voltage level detection means comprises first means for measuring the voltage of said battery relative to said low voltage cutoff level, said first measuring means having a first output voltage, said first output voltage being equal to said stable reference voltage when said battery voltage falls to said low cutoff voltage, and low voltage comparing means for determining when said first output voltage is equal to said stable reference voltage.

11. The device of claim 10, wherein said high voltage level detection means comprises second means for measuring the voltage of said battery relative to said high voltage cutoff level, said second measuring means having a second output voltage, said second output voltage being equal to said stable reference voltage when said battery voltage falls to said high cutoff voltage, and high voltage comparing means for determining when said second output voltage is equal to said stable reference voltage.

12. The device of claim 11, wherein said second detection means comprises sound-responsive means for detecting noise produced by operation of said engine or operation of said starter motor, wherein responsiveness of said interrupting means to said high drain detection means is delayed by said short delay means long enough to allow operation of said starter motor to be detected by said sound-responsive means.

13. A battery drain limitation device, comprising:

a complementary dual voltage setpoint detection circuit for determining a low charge condition on said battery; and

an interruption circuit, responsive to said complementary dual voltage setpoint detection circuit, for disconnecting the flow of current from said battery when said low charge condition is detected.

14. The device of claim 13, further comprising a reset circuit for reconnecting the flow of current from said battery.

15. The device of claim 13, wherein said complementary dual voltage setpoint detection circuit is comprised of a high drain detection circuit and a low drain detection circuit.

16. The device of claim 15, wherein said high drain detection circuit is operable when said battery voltage falls below a low cutoff voltage, said low cutoff voltage being chosen so that under moderate to high drain conditions said battery retains about half its charge.

17. The device of claim 16, wherein said low drain detection circuit is operable a set time period after said battery voltage falls below a high cutoff voltage, said high cutoff voltage and said set time period being chosen so that under low to moderate drain conditions said battery retains about half its charge.