Methods and system for a battery

Abstract

Systems and methods for operating a redox flow battery system may include switching the redox flow battery system to an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode; in response to switching to the idle mode, repeatedly cycling operation of an electrolyte pump between an idling threshold flow rate less than a charging threshold flow rate and a deactivation threshold flow rate; and in response to switching to the charging mode, maintaining operation of the electrolyte pump at the charging threshold flow rate greater than the idling threshold flow rate. In this way, a responsiveness of the redox flow battery system to charging and discharging commands can be maintained while in idle, while reducing parasitic pumping losses due to pumping and heating, and reducing shunt current losses.

1 . A method of operating a redox flow battery system, the method comprising:
 operating the redox flow battery system in an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode; and   while operating the redox flow battery system in the idle mode,
 repeatedly cycling operation of an electrolyte pump between an active state and an inactive state, wherein the active state comprises pumping electrolyte via the electrolyte pump at an idling threshold flow rate that is less than a charging threshold flow rate, and wherein the inactive state comprises operating the electrolyte pump at a deactivation threshold flow rate that is less than the idling threshold flow rate. 
   
     
     
         2 . The method of  claim 1 , wherein the electrolyte pump is ON in the active state. 
     
     
         3 . The method of  claim 1 , wherein the redox flow battery system is switched from a different operational mode to being operated in the idle mode. 
     
     
         4 . The method of  claim 3 , wherein the different operational mode is the charging mode or the discharging mode. 
     
     
         5 . The method of  claim 1 , further comprising:
 switching operation of the redox flow battery system to the discharge mode;   in response to switching to the discharge mode, increasing the flow rate to be greater than the idling threshold flow rate; and   maintaining the flow rate at greater than the idling threshold flow rate while operating the electrolyte pump in the discharge mode.   
     
     
         6 . The method of  claim 1 , wherein operation of the electrolyte pump at the deactivation threshold flow rate is maintained for at least a first threshold duration, wherein operation of the electrolyte pump at the idling threshold flow rate is maintained for at least a second threshold duration, and wherein the first threshold duration is greater than the second threshold duration. 
     
     
         7 . The method of  claim 1 , wherein the electrolyte pump is OFF in the inactive state. 
     
     
         8 . A method of operating a redox flow battery system, the method comprising:
 operating the redox flow battery system in an idle mode during a condition when the redox flow battery system is operating outside of a charging mode and outside of a discharge mode while a DC current remains zero;   during operation in the idle mode,
 repeatedly cycling operation of at least one electrolyte pump between an active state and an inactive state, wherein the electrolyte pump is ON in the active state, wherein the active state comprises pumping electrolyte at an idling threshold flow rate less than a charging threshold flow rate, and wherein the inactive state comprises pumping electrolyte at a deactivation threshold flow rate that is less than the idling threshold flow rate; 
   switching to operation in the discharge mode; and   in response to switching to the discharge mode, maintaining operation of the at least one electrolyte pump at a discharge threshold flow rate.   
     
     
         9 . The method of  claim 8 , wherein cycling operation of the electrolyte pump between the active state and the inactive state includes deactivating the at least one electrolyte pump when switching to operation in the inactive state. 
     
     
         10 . The method of  claim 9 , wherein the electrolyte pump is OFF when in the inactive state. 
     
     
         11 . The method of  claim 8 , wherein the discharge threshold flow rate is greater than the idling threshold flow rate. 
     
     
         12 . The method of  claim 8 , wherein the idling threshold flow rate is adjusted based on an anticipated load demand of the redox flow battery system. 
     
     
         13 . The method of  claim 12 , wherein the idling threshold flow rate is adjusted higher in response to the anticipated load demand of the redox flow battery system being higher, and wherein the idling threshold flow rate is adjusted lower in response to the anticipated load demand of the redox flow battery system being lower. 
     
     
         14 . The method of  claim 8 , wherein the DC current is positive during the charging mode, and wherein the DC current is negative during the discharge mode. 
     
     
         15 . A redox flow battery system, comprising:
 a power module, including a plurality of redox flow battery cell stacks, each of the plurality of redox flow battery cell stacks including a respective redox flow battery cell having a positive electrolyte chamber and a negative electrolyte chamber;   an electrolyte pump capable of delivering electrolyte from an electrolyte tank to the power module;   and a power control system with a controller including instructions thereon, the instructions executable to:
 operate the redox flow battery system in an idle mode, wherein the idle mode includes operation of the redox flow battery system outside of a charging mode and outside of a discharge mode; and 
 while operating the redox flow battery system in the idle mode, 
 repeatedly cycle operation of an electrolyte pump between an active state and an inactive state, wherein the active state comprises pumping electrolyte via the electrolyte pump at an idling threshold flow rate that is less than a charging threshold flow rate, and wherein the inactive state comprises operating the electrolyte pump at a deactivation threshold flow rate that is less than the idling threshold flow rate. 
   
     
     
         16 . The system of  claim 15 , further comprising a heater thermally coupled to the electrolyte, wherein the instructions are further executable to reduce an electrolyte temperature to an idling threshold temperature in response to switching to the idle mode. 
     
     
         17 . The system of  claim 16 , wherein the idling threshold temperature is increased in response to an anticipated load demand of the redox flow battery system being higher, and the idling threshold temperature is decreased in response to the anticipated load demand of the redox flow battery system being lower. 
     
     
         18 . The system of  claim 17 , wherein power electronics are deactivated in response to switching to the idle mode. 
     
     
         19 . The system of  claim 18 , wherein the idling threshold temperature corresponds to a temperature below which electrolyte precipitation occurs. 
     
     
         20 . The system of  claim 15 , wherein the electrolyte pump is ON in the active state.