Method for determining battery pack temperature and state of charge

Abstract

Disclosed is a battery system comprising a battery pack having a plurality of cells, each of the plurality of cells each having a cell temperature; a battery management system coupled to the battery pack and designed to obtain temperature plurality of temperatures from the battery pack wherein the battery management system is configured to output a single battery pack temperature value. Further disclosed is a battery system comprising a battery pack having a plurality of cells, each of the plurality of cells each having a cell state of charge; a battery management system coupled to the battery pack and designed to obtain a plurality of state of charges from the battery pack, wherein the battery management system is configured to output a single battery pack state of charge value.

We claim: 
     
         1 . A battery system comprising:
 a. a battery pack having a plurality of cells, each of the plurality of cells each having a cell temperature such that the battery pack comprises a plurality of cell temperatures;   b. a battery management system coupled to the battery pack and designed to obtain a plurality of temperatures from the battery pack and output a single battery temperature, the battery management system including:
 i. a high temperature threshold value; 
 ii. a low temperature threshold value; 
 iii. a drop value; 
   c. wherein the battery management system is further configured to:
 i. using the plurality of cell temperatures, calculate a maximum value, a minimum value, a high-middle value, and a low-middle value; 
 ii. if a first criteria is satisfied, assign a high value to the battery temperature; 
 iii. if a second criteria is satisfied but not the first criteria, assign a mid-high value to the battery temperature; 
 iv. 
 v. if a third criteria is satisfied but not the first or second criteria, assign a mid-low value to the battery temperature; 
 vi. if a fourth criteria is satisfied but not the first, second, or third criteria, assign a low value to the battery temperature; and 
 vii. output the battery temperature as a single battery pack temperature value. 
   
     
     
         2 . The system of  claim 1 , wherein the battery management system is further configured to use the cell temperature and threshold values to determine if there is a battery fault or error. 
     
     
         3 . The system of  claim 1 , wherein the battery management system is further configured to assign the minimum value to the battery temperature when none of the criteria are fulfilled. 
     
     
         4 . The system of  claim 1 , wherein the battery management system is further configured to assign the average value to the battery temperature when none of the criteria are fulfilled. 
     
     
         5 . The battery system of  claim 1 , wherein the battery system is configured to obtain a state of charge from each of the plurality of batteries. 
     
     
         6 . The battery system of  claim 5 , wherein the battery management system is further configured to evaluate the state of charge from each of the plurality of batteries against certain criteria. 
     
     
         7 . The battery system of  claim 6 , wherein the battery management system outputs a single state of charge for the battery. 
     
     
         8 . A method of determining battery pack temperature using the system of  claim 1 . 
     
     
         9 . A system for determining battery pack state of charge, the system comprising:
 a. a battery management system coupled to the battery pack and designed to obtain a plurality of state of charge readings from the plurality of cells and output a single battery state of charge, the battery management system including:
 i. a high state of charge threshold value; 
 ii. a low state of charge threshold value; 
 iii. a drop value; 
   b. wherein the battery management system is further configured to:
 i. if a first criteria is satisfied, assign a high value to the battery state of charge; 
 ii. if a second criteria is satisfied but not the first criteria, assign a mid-high value to the battery state of charge; 
 iii. if a third criteria is satisfied but not the first or second criteria, assign an average of the obtained cell temperatures to the battery state of charge; 
 iv. if a fourth criteria is satisfied but not the first, second, or third criteria, assign a mid-low value to the battery state of charge; 
 v. if a fifth criteria is satisfied but not the first, second, third, or fourth criteria, assign a low value to the battery temperature; and 
 vi. output a single battery pack state of charge value. 
   
     
     
         10 . The system of  claim 9 , wherein the battery management system is further configured to use the cell state of charge and threshold values to determine if there is a battery fault or error. 
     
     
         11 . A method for determining a battery pack temperature, the method comprising:
 a. assigning a plurality of temperature threshold variables;   b. obtaining a plurality of temperature readings from a battery pack;   c. evaluating the plurality of temperature readings against a plurality of criteria, including:
 i. determining if a first criteria is satisfied and, if so, assigning a high value to the battery temperature; 
 ii. determining if a second criteria is satisfied but not the first criteria, and if so, assigning a mid-high value to the battery temperature; 
 iii. determining if a third criteria is satisfied but not the first or second criteria, and if so, assigning an average of the obtained cell temperatures to the battery temperature; 
 iv. determining if a fourth criteria is satisfied but not the first, second, or third criteria, and, if so, assigning a mid-low value to the battery temperature; 
 v. determining if a fifth criteria is satisfied but not the first, second, third, or fourth criteria, and, if so, assigning a low value to the battery temperature; and 
   d. outputting a single battery pack temperature value.   
     
     
         12 . The method of  claim 11  further comprising:
 a. assigning a plurality of state of charge threshold variables; 
 b. obtaining a plurality of state of charge readings from the battery pack; 
 c. evaluating the plurality of state of charge readings against a plurality of criteria; and 
 d. outputting a single battery pack state of charge to a vehicle system. 
 
     
     
         13 . The method of  claim 9 , wherein evaluating the plurality of state of charge readings against a plurality of criteria further comprises:
 a. determining if a first criteria is satisfied and, if so, assigning a high value to the battery state of charge;   b. determining if a second criteria is satisfied but not the first criteria, and if so, assigning a mid-high value to the battery state of charge;   c. determining if a third criteria is satisfied but not the first or second criteria, and if so, assigning an average of the obtained cell temperatures to the battery state of charge;   d. determining if the fourth criteria is satisfied but not the first, second, or third criteria, and, if so, assigning a mid-low value to the battery state of charge.   
     
     
         14 . A vehicle system which performs the method of  claim 11 . 
     
     
         15 . A vehicle having the system of  claim 1 . 
     
     
         16 . A vehicle having the system of  claim 9 . 
     
     
         17 . The battery system of  claim 1 , wherein the first criteria is whether the maximum value exceeds the high temperature threshold value. 
     
     
         18 . The battery system of  claim 1 , wherein the second criteria is whether the high-middle value is less than or equal to the maximum value which is also less than the high temperature threshold value. 
     
     
         19 . The battery system of  claim 1 , wherein the third criteria is whether the low temperature threshold value is less than the minimum value which is less than or equal to the low-middle value. 
     
     
         20 . The battery system of  claim 1 , wherein the fourth criteria is whether the minimum value is less than or equal to the low temperature threshold value.