Modular battery system having a pluggable charging module

• US 5,635,814 A
• Filed: 02/16/1995
• Issued: 06/03/1997
• Est. Priority Date: 02/16/1995
• Status: Expired due to Fees

• Current Assignee: International Components Corporation (ICC-Nexergy, Inc)
• Original Assignee: International Components Corporation (ICC-Nexergy, Inc)
• Inventors: Pontius, Darrel W., Bylund, Bradley E., Afzal, Ejaz, Frank, Charles W. Jr.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US08/389,248
• Time in Patent Office: 838 Days
• Field of Search: 320/2, 320/5, 320/30, 320/35, 320/36, 320/39, 320/40, 320/49, 320/57, 429/96, 429/97, 429/98, 429/99, 429/100, 429/149, D13/103, D13/107, D13/108
• US Class Current: 320/111
• CPC Class Codes: H01M 50/213 adapted for cells having curved cross-section, e.g. round or elliptic H01M50/209, H01M50/216 take precedence
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0045 concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A modular battery system for a portable device including a charging module with a retractable plug and charging circuit for converting an AC line voltage to a DC battery charging current. The charging module combines with a battery module and optional fuel gauge (if present) to form a single unit for recharging, preconditioning the battery, and connection to the portable device. The modules are releasably connected, preferably involving conductive fasteners, so that a user may connect a new battery module to an old charging module. The releasable connection serves as both the mechanical and the electrical interface between the battery module and the charging module. The conductive fasteners may be located in different positions on the modules to accommodate different connector geometries. The charging module may also combine with a battery mounting module, rather than the battery module, so that the system works with conventional battery packs. The preferred charging module incorporates a PWM charging circuit having a transformer with a primary winding, a secondary winding, and a control winding. The control winding has two purposes, it provides feedback information and it provides operating current for the continued operation of the PWM charging circuit. The transformer is designed so that the primary winding has a better magnetic coupling with the secondary winding than with the control winding so that the charging circuit will run in a safe low-power "standby" mode in the event of a short circuit in the secondary circuit. The feedback circuit from the control winding is preferably filtered through a low-pass filter to remove "flyback" transients.

Claims

1. A modular battery system useful for recharging a rechargeable battery and for applying power to a pair of terminals of a portable device, the system comprising:

a battery module for supporting the rechargeable battery within the battery module;

a charging module having a retractable plug for connecting the charging module to an AC line voltage, said retractable plug controlled by a rotatable thumbwheel disposed in said charging module, said thumbwheel for moving said retractable plug, and a battery charging circuit for converting the AC line voltage to a DC charging current;

interconnecting means for releasably mechanically fastening the charging module to the battery module, said interconnecting means comprising;

a pair of conductive nuts connected to the rechargeable battery cells in the battery module;

a pair of battery module apertures in a side of the battery module, the conductive nuts accessible through the battery module apertures;

a pair of charging module apertures through the charging module aligned with the battery module apertures; and

a set of conductive screws extending through the charging module apertures and battery module apertures into the conductive nuts to mechanically and electrically couple the two modules, the conductive screws and nuts making electrical contact with and between the charging module'"'"'s charging circuit and the battery module'"'"'s rechargeable battery, said fastening couple electrically connecting the circuit board of said charging module to a thermistor in said battery module;

the battery module including connecting means for engaging with the interconnecting means each being electrically conductive for conducting the DC charging current of the charging module to the rechargeable battery cells of the battery module; and

means for attaching the battery system, as a unit, to apply power to the terminals of the portable device.

2. The modular battery system of claim 1 wherein the conductive screws make electrical contact with the charging module'"'"'s charging circuit by compressing a contact between the screw head and a conductive pad on the circuit board containing the charging circuit.

3. A modular battery system useful for recharging a rechargeable battery and for applying power to a pair of terminals of a portable device, the system comprising:

a rechargeable battery comprising a plurality of battery cells, means for binding the cells in a stacked arrangement, and means for electrically connecting the cells to define a pair of battery terminals;

a battery module for supporting the rechargeable battery within the battery module;

a charging module having a retractable plug for connecting the charging module to an AC line voltage, said retractable plug controlled by a rotatable thumbwheel disposed in said charging module, said thumbwheel for moving said retractable plug, and a battery charging circuit for converting the AC line voltage to a DC charging current, said charging module sandwiched between the battery module and the portable device when the battery system is connected to the portable device;

interconnecting means for releasably mechanically connecting the charging module to the battery module, said interconnecting means including;

a pair of conductive nuts connected to the rechargeable battery cells in the battery module;

a pair of apertures in a side of the battery module, the conductive nuts accessible through the battery module apertures;

a pair of apertures through the charging module aligned with the battery module apertures; and

a set of conductive screws extending through the charging module apertures and battery module apertures into the conductive nuts to mechanically and electrically couple the two modules, the conductive screws and nuts making electrical contact with and between the charging module'"'"'s charging circuit and the battery module'"'"'s rechargeable battery and thermistor;

the battery module including connecting means for engaging with the interconnecting means, and the connecting means and the interconnecting means each being electrically conductive for conducting the DC charging current of the charging module to the rechargeable battery cells of the battery module; and

means for attaching the battery system, as a unit, to apply power to the terminals of the portable device.

4. The modular battery system of claim 3 wherein the conductive screws make electrical contact with the charging module'"'"'s charging circuit by compressing a contact between the screw head and a conductive pad on the circuit board containing the charging circuit.

5. A modular battery system for a portable device, comprising:

a housing separable from the portable device;

means for supporting a rechargeable battery within the housing;

a retractable electrical plug attached to the housing for connecting to an alternating current supply line, said retractable plug controlled by a rotatable thumbwheel disposed in said charging module, said thumbwheel for retracting and extending said retractable plug from within said housing; and

a battery charging circuit within the housing for converting an AC voltage from the plug to a DC battery charging current, the battery charging circuit comprising;

a transformer having a primary winding, a secondary winding, and a control winding, the primary winding having a reduced magnetic coupling with the control winding as compared to the secondary winding;

a switch for periodically grounding the primary winding to store magnetic energy in response to a switching control pulse of variable width; and

a pulse width modulation (PWM) controller circuit for providing the switching control pulse in response to a feedback signal from the control winding of the transformer, the control winding further providing the PWM controller circuit with a bootstrapped operating voltage for continued operation, the reduced coupling between the primary winding and the control winding preventing the PWM controller circuit from continuing to receive an adequate bootstrapped operating voltage in the event of a short circuit connected to the secondary winding.

6. A charger for use with a portable device having a battery mounting surface and a battery pack having a device mounting surface that electromechanically connects to the battery mounting surface, the charger comprising:

a battery charging circuit for converting an AC line voltage to a DC charging current;

a supplemental battery mounting surface that matches the portable device'"'"'s battery mounting surface for electromechanically mounting the battery pack to the charger rather than the portable device;

a supplemental device mounting surface that matches the battery pack'"'"'s device mounting surface for electromechanically mounting the charger and a mounted battery pack to the portable device for operating the portable device by discharging the mounted battery pack through the charger, the charger remaining present during operation of the portable device for later recharging the mounted battery pack;

means for alternatively connecting the charger and the mounted battery pack to the AC line voltage for charging the battery pack with the DC charging current;

a device module having the supplemental device mounting surface;

a battery mounting module having the supplemental battery mounting surface; and

means for electromagnetically connecting the battery mounting module to the device mounting module wherein the electromechanical connecting means comprises a plurality of conductive screws and conductive nuts.