Battery pack and over-voltage alarm therefor

• US 6,297,615 B1
• Filed: 05/25/2000
• Issued: 10/02/2001
• Est. Priority Date: 06/09/1999
• Status: Expired due to Fees

• Current Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Original Assignee: Snap-On Technologies Incorporated (Snap-On Incorporated)
• Inventors: Crass, Matthew M.
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/578,094
• Time in Patent Office: 495 Days
• Field of Search: 320/112, 320/134, 320/162, 320/DIG.18, 320/DIG.19, 340/636
• US Class Current: 320/112
• CPC Class Codes: H01M 10/06 Lead-acid accumulators semi-lead accumulators H01M10/20
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 6/5033 used as charging means for another battery
• CPC Class Codes: H01M 6/5044 Cells or batteries structurally combined with cell condition indicating means
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/19 Charger status, e.g. voltmeter

Abstract

A battery pack has a pair of input/output terminals adapted to be connected across a source of charging voltage, and a lead-acid battery connected across the input/output terminals. A Zener diode is connected in series with a resistance across the input/output terminals, the resistance forming part of a trigger circuit for triggering an alarm signal to actuate a visible and/or audible annunciator when the charging voltage exceeds a threshold level. In one embodiment the trigger circuit is an IC comparator having one input connected to a reference voltage drive from a voltage divider connected across the input/output terminals, and the other input connected to the trigger voltage across the resistance in series with the Zener. In another embodiment the trigger circuit includes a pair of transistors, one being turned ON by the trigger voltage and in turn ON the second transistor to produce the output signal and provide a feedback to latch on the first transistor.

Claims

1. A battery pack comprising:

a housing;

a pair of input/output terminals coupled to the housing and adapted to be connected across a source of charging voltage;

a lead-acid battery having positive and negative electrodes respectively connected to the input/output terminals;

a threshold circuit including a Zener diode connected to the input/output terminals and establishing a threshold voltage;

a trigger circuit connected to the threshold circuit and to tie input/output terminals and generating an output signal when the charging voltage exceeds the threshold voltage;

the trigger circuit includes a potentiometer connected in series with the Zener diode across the input/output terminals and having a wiper terminal,

a first transistor switch connected to the threshold circuit and including a transistor having a base connected to the potentiometer wiper and an emitter-collector junction connected across the input/output terminals and becoming conductive in response to to charging voltage exceeding the threshold level, and

a second transistor switch connected to the input/output terminals and to the first transistor switch and becoming conductive in response to conduction of the first transistor switch;

a feedback circuit connected from the output of the second transistor switch to a control input of the first transistor switch and responsive to conduction of the first transistor switch for latching it in a conductive condition; and

an annunciator coupled to the second transistor switch and responsive to conduction thereof to produce an indication of an over-voltage condition,

the battery and the circuits and the annunciator all being disposed in the housing.

2. The battery pack of claim 1, wherein the annunciator includes an audible annunciator.

3. The battery pack of claim 1, wherein the annunciator includes a visible annunciator.