Protection Methods, Protection Circuits and Protection Devices for Secondary Batteries, a Power Tool, Charger and Battery Pack Adapted to Provide Protection Against Fault Conditions in the Battery Pack

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.

1 - 24 . (canceled) 
   
   
       25 . A method of providing over-voltage protection in a battery pack removably attachable to a cordless power tool and a charger, the battery pack operatively attached to the charger charging the pack, comprising:
 sensing an over-voltage fault condition in the pack; and   terminating charge current in the battery pack or charger based on the sensed fault condition.   
   
   
       26 . The method of  claim 25 , wherein terminating includes generating a control signal in the pack to turn off a semiconductor device in the pack that is adapted to limit or interrupt current in a charge path of the pack. 
   
   
       27 . The method of  claim 25 , wherein terminating further includes
 generating a control signal in the pack, and   communicating the control signal to the charger to turn off a semiconductor device in the charger that is adapted to limit or interrupt current in a charge path of the charger to terminate current flow in the battery pack.   
   
   
       28 . A watchdog circuit of a charger, the charger operatively attached to a battery pack for charging the battery pack, the watchdog circuit monitoring parameters in both the battery pack and the charger for one or more control signals from the battery pack or charger to terminate current flow in the battery pack. 
   
   
       29 . The watchdog circuit of  claim 28 , wherein the parameters include one or more of battery pack temperature, individual cell voltages, battery stack voltage, a charge current reset pulse from the battery pack, and a clock reset pulse from the battery pack, and/or a charge current reset pulse from the charger. 
   
   
       30 . In a charger adapted to charge a battery pack, the charger and battery pack part of a cordless power tool system, the charger comprising:
 a charge current interruption circuit monitoring parameters in both the battery pack and the charger for one or more control signals from the battery pack or charger to terminate current flow in the battery pack.   
   
   
       31 . The charge current interruption circuit of  claim 30 , wherein the parameters include one or more of battery pack temperature, individual cell voltages, battery stack voltage, a charge current reset pulse from the battery pack, a clock reset pulse from the battery pack, and/or a charge current reset pulse from the charger. 
   
   
       32 - 49 . (canceled)