US 7,508,171 B2Granted

Protection methods, protection circuits and protective devices for secondary batteries, a power tool, charger and battery pack adapted to provide protection against fault conditions in the battery pack

AssigneeBlack & Decker Inc.

InventorsDave Carrier, Steve Phillips, Jeffrey J. Francis, R. Roby Bailey, Danh Thanh Trinh, Andrew E. Seman, Jr., Christopher R. Yahnker, Daniele C. Brotto, John C. Vanko, Robert Bradus

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Abstract

In a cordless power tool system, protection methods, circuits and devices are provided to protect against fault conditions within a battery pack that is operatively attached to a power tool or charger, so as to prevent internal or external damage to the battery pack or attached tool or charger. The exemplary methods, circuits and devices address fault conditions such as over-charge, over-discharge, over-current, over-temperature, etc.

Claims38

Dependent claims

A battery pack configured to power a cordless power tool and including a plurality of serially-connected battery cells, the battery pack including a protection arrangement adapted to limit or interrupt current in the battery pack upon a fault condition that is sensed in the battery pack;

and
at least one protection circuit monitoring pack voltage for a potential over-discharge fault condition in the pack and adapted to perform an automatic shutdown of current flow in the pack if the monitored voltage reaches a given dynamic voltage threshold, wherein the dynamic voltage threshold is varied by subtracting a proportion of instant discharge current from an absolute threshold level to compensate for impedance of the battery pack and to avoid a spurious automatic shutdown of current flow, if monitored voltage momentarily drops below the threshold.

Dependencies are inferred from the claim text.

Facts

Application: 10/959,193Filed 7 Oct 2004 · us provisional application
Priority: 14 Oct 2003
Published: US 2005/0077878 A114 Apr 2005
Granted: 24 Mar 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification34 codes

B25F 5/00
Details or components of portable power-driven tools not particularly related to the
B60L 53/18
Conductive energy transfer: cables specially adapted for charging electric vehicles
H01M 10/42
Secondary cells; Manufacture thereof: methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
H01M 10/425
Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells: structural combination with electronic…