Battery management of multi-cell batteries

Abstract

Apparatus for a modular battery management system for a battery having a plurality of cells. The system includes interchangeable chargers each associated with a slave module. The chargers are connected to each cell and a master module controlling the system. All the modules receive power through a transfer switch that selectively switches between external sources and the battery. With the transfer switch connecting the battery to the charger modules, each charger operates independently to maintain its associated cell. Each charger is electrically isolated from the other chargers. The external sources provide capacity information used by the master module. The slave modules are autonomous and shut down the battery and disconnect the module when a critical parameter of the cell is reached. When the battery is in service and a cell parameter approaches the critical level, the master controller instructs the corresponding slave module to charge the cell using battery power.

What is claimed is: 
     
         1 . An apparatus for managing a battery with a plurality of cells, said apparatus comprising:
 a plurality of chargers, each one of said plurality of chargers having an output configured to be electrically connected to at least one of the plurality of cells, each one of said plurality of chargers configured to charge said at least one of the plurality of cells, each one of said plurality of chargers having an input selectively connectable to the battery; and   a plurality of isolation circuits, each one of said plurality of isolation circuits associated with a corresponding one of said plurality of chargers, wherein each one of said plurality of isolation circuits electrically isolates the battery from said at least one of the plurality of cells associated with said corresponding one of said plurality of chargers.   
     
     
         2 . The apparatus of  claim 1  further including a transfer switch, said transfer switch operatively connected to said plurality of chargers, said transfer switch having a first state wherein an external power source is connected to power said plurality of chargers, said transfer switch having a second state wherein the battery is connected to provide power to said plurality of chargers. 
     
     
         3 . The apparatus of  claim 1  wherein each one of said plurality of chargers is energized to charge an associated cell after an associated cell monitoring circuit detects a first operating parameter with a specified value and said transfer switch is in said second state. 
     
     
         4 . The apparatus of  claim 1  further including a first load connection configured to electrically connect a first load across the battery and a second load connection configured to electrically connect a second load across a portion of the battery, and said portion of the battery defined as at least one and less than all of the plurality of cells of the battery, wherein said portion of the battery is maintained by at least one of said plurality of chargers. 
     
     
         5 . The apparatus of  claim 1  further including a plurality of modules, each one of said plurality of modules including a corresponding one of said plurality of chargers, each one of said plurality of modules including a cell monitoring circuit and a module disconnect switch, wherein each said module disconnect switch operates to isolate said at least one of the plurality of cells from said corresponding one of said plurality of chargers when said cell monitoring circuit determines said at least one of the plurality of cells has a first operating parameter outside an acceptable range. 
     
     
         6 . The apparatus of  claim 5  wherein each one of said plurality of modules is initialized with a unique identification based on an identification of said at least one of the plurality of cells. 
     
     
         7 . An apparatus for managing a battery having a plurality of cells that are series connected, said apparatus comprising:
 a first charger, said first charger having a first charger output electrically connectable to a first set of cells including at least one of the plurality of cells, said first charger having a first charger input electrically connectable to the battery; and   a second charger, said second charger having a second charger output electrically connectable to a second set of cells including at least one of the plurality of cells, said first set of cells and said second set of cells being disjoint sets, said second charger having a second charger input electrically connectable to the battery.   
     
     
         8 . The apparatus of  claim 7  further including a first isolation circuit associated with said first charger wherein the battery is electrically isolated from said first set of cells, and further including a second isolation circuit associated with said second charger wherein said the battery is electrically isolated from said second set of cells. 
     
     
         9 . The apparatus of  claim 7  further including a first isolation circuit associated with said first charger wherein said first charger has said first charger output electrically isolated from said first charger input, and further including a second isolation circuit associated with said second charger wherein said second charger has said second charger output electrically isolated from said second charger input. 
     
     
         10 . The apparatus of  claim 7  further including a transfer switch, said transfer switch operatively connected to said first charger and said second charger, said transfer switch having a first state wherein an external power source is connected to provide power to said first charger and said second charger, said transfer switch having a second state wherein the battery is connected to provide power to said first charger and said second charger. 
     
     
         11 . The apparatus of  claim 10  wherein said first charger is energized to charge said first set of cells after a cell monitoring circuit associated with said first charger detects a first operating parameter with a specified value and said transfer switch is in said second state. 
     
     
         12 . The apparatus of  claim 10  wherein said first charger is energized to charge said first set of cells after a cell monitoring circuit associated with said first charger detects a first operating parameter with a specified value and said transfer switch is in said second state, and said second charger is energized to charge said second set of cells after a cell monitoring circuit associated with said second charger detects a second operating parameter with a specified value and said transfer switch is in said second state. 
     
     
         13 . The apparatus of  claim 7  further including a first module and a second module, said first module including said first charger, said second module including said second charger. 
     
     
         14 . The apparatus of  claim 13  wherein each one of said first module and said second module further includes a cell monitoring circuit and a module disconnect switch, wherein said first module disconnect switch in said first module operates to isolate said first set of cells from said first module when said cell monitoring circuit determines said first set of cells has a first operating parameter outside an acceptable range, and said second module disconnect switch in said second module operates to isolate said second set of cells from said second module when said cell monitoring circuit determines said second set of cells has a second operating parameter outside an acceptable range. 
     
     
         15 . The apparatus of  claim 7  further including a first load connection configured to electrically connect a first load across the battery and a second load connection configured to electrically connect a second load across a portion of the battery, said portion of the battery defined as at least one and less than all of the plurality of cells of the battery, wherein said portion of the battery is maintained by at least one of said first charger and said second charger. 
     
     
         16 . An apparatus for managing a battery having a plurality of cells, said apparatus comprising:
 a transfer switch having a first state wherein an external power source is connected to provide power, said transfer switch having a second state wherein the battery is connected to provide power; and   a plurality of chargers each configured to be electrically connected to an associated cell of the battery, said plurality of chargers connected to said transfer switch whereby said plurality of chargers receive power from said external source with said transfer switch in said first state and from the battery with said transfer switch in said second state, each one of said plurality of chargers configured to charge said associated cell.   
     
     
         17 . The apparatus of  claim 16  further including a first load disconnect switch operatively connected to a master module, said first load disconnect switch configured to isolate a first load from the battery, said master module causing said first load disconnect switch to isolate said first load from the battery when any one of the plurality of cells is determined to have an operating parameter outside an acceptable range as determined by a cell monitoring circuit associated with a corresponding one of said plurality of chargers associated with said one of said plurality of cells. 
     
     
         18 . The apparatus of  claim 16  further including a first load connection configured to electrically connect a first load to the battery and a second load connection configured to electrically connect a second load across a portion of the battery, said portion of the battery defined as at least one and less than all of the plurality of cells of the battery, wherein each one of said plurality of cells in said portion of the battery is independently maintained by a corresponding one of said plurality of chargers. 
     
     
         19 . The apparatus of  claim 16  wherein a master module receives data from said external power source, said data including a capacity of said external power source, and said master module controlling said plurality of chargers to ensure said capacity is not exceeded by said plurality of said chargers. 
     
     
         20 . The apparatus of  claim 16  further including a connector between said external power source and said transfer switch, said connector communicating a connector status with a master module, said connector status including information that said external power source is about to be disconnected from said transfer switch, and said master module causing said external power source to be electrically disconnected before said connector breaks an electrical connection between said external power source and said transfer switch.