High-current battery management system

Abstract

An apparatus includes a microcontroller and isolation circuitry including multiple transistor-based switches arranged electrically in parallel to isolate a battery from a load source, wherein the battery is capable of providing high levels of current. The apparatus includes a first buss bar to which first pins of the multiple switches are connected, wherein the first buss bar is to be connected to the battery and a second buss bar to which second pins of the multiple switches are connected, wherein the second buss bar is to be connected to the load source. A microcontroller is programmed to control the multiple switches substantially simultaneously to isolate the battery from the load source upon detecting a predetermined condition.

What is claimed is: 
     
         1 . An apparatus comprising:
 an isolation circuitry including multiple, transistor-based switches arranged electrically in parallel to isolate a battery from a load source, wherein the battery is capable of providing high levels of current;   a first buss bar to which first pins of the multiple switches are connected, wherein the first buss bar is to be connected to the battery;   a second buss bar to which second pins of the multiple switches are connected, wherein the second buss bar is to be connected to the load source; and   a microcontroller programmed to control the multiple switches substantially simultaneously to isolate the battery from the load source upon detecting a predetermined condition.   
     
     
         2 . The apparatus of  claim 1 , further comprising a heat-conducting bar made of a heat-conducting metal and thermally coupled to the multiple switches, to equalize a temperature across the multiple switches. 
     
     
         3 . The apparatus of  claim 1 , further comprising:
 a switching driver circuit operatively coupled to the microcontroller and to turn on and off the multiple switches responsive to signals from the microcontroller; and   a plurality of metal traces connecting gates of the multiple switches to the switching driver circuit that are of equal length, such that a signal from the switching driver circuit arrives at the multiple switches at substantially the same time.   
     
     
         4 . The apparatus of  claim 1 , wherein the multiple switches are arranged in a first subarray and a second subarray, wherein a number of the multiple switches in the first subarray are equal to those in the second subarray. 
     
     
         5 . The apparatus of  claim 4 , wherein the first buss bar and the second buss bar each include a first conductive path and a second conductive path that connect, wherein the multiple switches of the first subarray are located in a line along an edge of the first conductive path and the multiple switches of the second subarray are located in a line along an edge of the second conductive path. 
     
     
         6 . The apparatus of  claim 5 , wherein a first switch in the first subarray and a first switch in the second subarray are located so as to be equidistant from the load source along, respectively, the first buss bar and the second buss bar in order to synchronize a time for current to arrive at each of the first switches. 
     
     
         7 . The apparatus of  claim 5 , further comprising:
 a current measuring circuit to:
 determine a first current of the first conductive path; 
 determine a second current of the second conductive path; and 
 notify the microcontroller of the first current and the second current; and 
   wherein the microcontroller is further to generate an alert indicative of the first current and the second current differing beyond a pre-defined threshold amount indicative of degradation of one or more of the multiple switches.   
     
     
         8 . The apparatus of  claim 1 , wherein the predetermined condition comprises one of: a short circuit in the load source, overheating of the battery, overheating of the isolation circuitry, a low-voltage threshold of the battery, or a user-initiated shut off. 
     
     
         9 . The apparatus of  claim 1 , further comprising a metal oxide varistor (MOV) coupled to the first buss bar or to the second buss bar in parallel with the multiple switches, to provide voltage suppression by shunting current caused by high voltages away from the multiple switches. 
     
     
         10 . The apparatus of  claim 1 , further comprising:
 a printed circuit board located between the first buss bar and the second buss bar and to which is attached the microcontroller; and   a thermal sensor attached to the printed circuit board and operatively coupled to the microcontroller, wherein the thermal sensor is to:
 measure a temperature level of the second buss bar; and 
 responsive to detecting a temperature above a pre-determined threshold temperature, send a signal as an over-temperature indicator to the microcontroller; and 
   wherein the microcontroller is to switch off the multiple switches responsive to the signal.   
     
     
         11 . The apparatus of  claim 1 , further comprising measurement circuitry to:
 measure, to a high level of accuracy, a resistance of one buss bar selected from the first buss bar and the second buss bar;   determine a current level through the one buss bar in view of a voltage measured across the one buss bar and the resistance of the one buss bar; and   detect a high current surge condition in view of the current level being over a predetermined threshold high current.   
     
     
         12 . The apparatus of  claim 11 , wherein the load source is a vehicle, and wherein the measurement circuitry is further to distinguish the high current surge condition in view of the current level being below the predetermined threshold high current. 
     
     
         13 . An apparatus comprising:
 an isolation circuitry including multiple, transistor-based switches arranged electrically in parallel to isolate a battery from a load source, wherein the battery is capable of providing high levels of current of at least 400 amperes;   a switching driver circuit operatively coupled to the isolation circuitry such as to switch off the multiple switches simultaneously; and   a microcontroller operatively coupled to the switching driver circuit, wherein the microcontroller is to direct the switching driver circuit to turn off the multiple switches responsive to detecting a predetermined condition.   
     
     
         14 . The apparatus of  claim 13 , wherein the multiple switches are arranged in a first subarray and a second subarray, wherein a number of the multiple switches in the first subarray are equal to those in the second subarray, wherein a first switch in the first subarray and a first switch in the second subarray are located so as to be equidistant from the load source. 
     
     
         15 . The apparatus of  claim 13 , wherein the multiple switches operate within a range of switching rates, and wherein the switching driver circuit is to switch off the multiple switches at a slowest rate within the range of switching rates without exceeding a maximum allowable power dissipation caused by switching. 
     
     
         16 . The apparatus of  claim 13 , wherein the battery includes a plurality of banks of cells, further comprising an analog-to-digital converter (ADC) to measure a voltage of a bank of the plurality of banks of cells and to send the voltage to the microcontroller, wherein the microcontroller is further to:
 determine a number of charge cycles in which the voltage has cycled between a specified first voltage and a specified second voltage;   determine an amount of time in which the bank is at a critical voltage level that depends on a type of the battery; and   generate an alert indicative of degradation of the bank responsive to passing a threshold number of charge cycles and a pre-defined amount of time at the critical voltage.   
     
     
         17 . The apparatus of  claim 13 , wherein the predetermined condition comprises a high pre-set current level over a short period of time, wherein an amount of the high pre-set current level depends on the load source. 
     
     
         18 . The apparatus of  claim 13 , wherein the predetermined condition comprises a reserve voltage below which the microcontroller is to generate an alert to reset the battery in order to access reserve capacity. 
     
     
         19 . The apparatus of  claim 13 , wherein the predetermined condition comprises a low-voltage threshold below which the microcontroller is further to:
 shut off the multiple switches to protect the battery from over-discharging; and   require charging the battery above the low-voltage threshold before accepting a reset to begin drawing on the battery again.   
     
     
         20 . The apparatus of  claim 13 , wherein the microcontroller is further to:
 retrieve a critical low voltage for the battery;   track an amount of time at which the battery is at or below the critical low voltage;   responsive to the battery being at or below the critical low voltage for a predetermined minimum period of time, cause the battery to enter a hibernation mode of extremely low current consumption when compared with normal operation of the battery; and   require recharging the battery above the critical low voltage before accepting a reset to again draw power from the battery.   
     
     
         21 . The apparatus of  claim 13 , wherein the load source is a vehicle, and wherein the microcontroller is further to:
 restrict amperes available to the vehicle, as drawn through the multiple switches, to an amount insufficient to turn on the vehicle; and   reverse the restriction in amperes responsive to receiving a signal indicating presence of an authorized operator.   
     
     
         22 . An apparatus comprising:
 an isolation circuitry including multiple, transistor-based switches arranged electrically in parallel on a circuit board, wherein the isolation circuitry is to isolate a load source from a battery that is capable of providing high levels of current;   a surge detection circuit including an operation amplifier to detect a surge in current by measuring a voltage difference between source and drain of a subset of the multiple switches;   a surge measuring circuit to measure a magnetic field and to determine a current level of the surge in current; and   a microcontroller operatively coupled to the surge detection circuit and the surge measuring circuit, wherein the microcontroller is to:
 receive a first signal from the surge detection circuit, wherein the first signal is indicative of detecting the surge in current; 
 turn on the surge measuring circuit responsive to the first signal; 
 receive the current level of the surge from the surge measuring circuit; and 
 send a second signal to switch off the multiple switches responsive to determining that the current level is above a pre-defined threshold current level indicating a short circuit. 
   
     
     
         23 . The apparatus of  claim 22 , wherein the surge measuring circuit includes a Hall Effect sensor attached to the circuit board with which to measure the magnetic field. 
     
     
         24 . The apparatus of  claim 22 , wherein the surge detection circuit further includes a digital-to-analog (ADC) circuit to generate the first signal responsive to the surge detection circuit detecting the surge in current. 
     
     
         25 . The apparatus of  claim 22 , wherein the microcontroller is further to set the pre-defined threshold current level according to a size of the battery or a size of the load source.