Application independent map-based cycle life testing of battery cells
A method and system for application independent map-based cycle life testing of battery cells is provided. A target depth of discharge (DOD) and a charge/discharge current level is selected for the battery test. The battery is discharged to the target DOD. The battery is cycled within the DOD range one or more times, wherein the cycling comprises a charge pulse and a discharge pulse at the selected current levels. A reference performance test (RPT) is performed on the battery, wherein the RPT comprises a static capacity test and a dynamic power test. The cycling and RPT testing are repeated until an end of test condition is detected.
1. A method for cycle life testing of a battery, said method comprising:
selecting a target depth of discharge (DOD) for said battery test;
selecting a DOD range that includes a DOD range minimum value that is less than the target depth of discharge and a DOD range maximum value that is greater than the target depth of discharge for said battery test;
selecting a charge current (I c ) and a discharge current (I d ) for said battery test;
discharging said battery to said target DOD;
cycling said battery within said DOD range one or more times, wherein said cycling comprises a charge pulse at I c and a discharge pulse I d ;
performing a reference performance test (RPT) on said battery, wherein said RPT comprises a static capacity test and a dynamic power test;
determining if an end of test condition has occurred;
repeating said cycling and said RPT testing until said end of test condition occurs; and
wherein said test is performed at a first power level, a second power level and a third power level, wherein said first power level is 39% to 41% of a rated power of said battery, said second power level is 24% to 26% of said rated power and said third power level is 9% to 11% of said rated power.
2. The method of claim 1 , wherein said rated power is the minimum of a measured discharge power and a measured charge power of said battery, said measurement performed at a DOD of said battery in the range of 49% to 51%.
3. The method of claim 1 , wherein said I d is selected as said test performance power level divided by the open circuit voltage of said battery at said target DOD.
4. The method of claim 3 , wherein said I c is selected as said I d divided by a scale factor, said scale factor in the range of 1.4 to 1.6.
5. The method of claim 1 , further comprising measuring battery voltage drift and adjusting the durations of said charge pulse and said discharge pulse based on closed loop proportional-integral control feedback in response to said measured battery voltage drift.
6. The method of claim 1 , further comprising maintaining said battery at a temperature of 29 to 31 degrees Celsius during said battery test.
7. The method of claim 1 , wherein said end of test condition comprises a drop in static capacity of said battery below 80% of a static capacity measurement of said battery performed prior to said battery test.
8. The method of claim 1 , wherein said end of test condition comprises a drop in dynamic discharge power of said battery below 70% of a dynamic power measurement of said battery performed prior to said battery test.
9. The method of claim 1 , wherein said end of test condition comprises exceeding a pre-determined testing time duration threshold.
10. An article comprising a non-transitory storage medium having stored thereon instructions that when executed by a machine result in the following operations:
selecting a target depth of discharge (DOD) for said battery test;
selecting a DOD range that includes a DOD range minimum value that is less than the target depth of discharge and a DOD range maximum value that is greater than the target depth of discharge for said battery test;
selecting a charge current (I c ) and a discharge current (I d ) for said battery test;
discharging said battery to said target DOD;
cycling said battery within said DOD range one or more times, wherein said cycling comprises a charge pulse at L and a discharge pulse I d ;
performing a reference performance test (RPT) on said battery, wherein said RPT comprises a static capacity test and a dynamic power test;
determining if an end of test condition has occurred; repeating said cycling and said RPT testing until said end of test condition occurs; and
wherein said test is performed at a first power level, a second power level and a third power level, wherein said first power level is 39% to 41% of a rated power of said battery, said second power level is 24% to 26% of said rated power and said third power level is 9% to 11% of said rated power.
11. The article of claim 10 , wherein said rated power is the minimum of a measured discharge power and a measured charge power of said battery, said measurement performed at a DOD of said battery in the range of 49% to 51%.
12. The article of claim 10 , wherein said I d is selected as said test performance power level divided by the open circuit voltage of said battery at said target DOD.
13. The article of claim 12 , wherein said I c is selected as said I d divided by a scale factor, said scale factor in the range of 1.4 to 1.6.
14. The article of claim 10 , further comprising measuring battery voltage drift and adjusting the durations of said charge pulse and said discharge pulse based on closed loop proportional-integral control feedback in response to said measured battery voltage drift.
15. The article of claim 10 , wherein said end of test condition comprises a drop in static capacity of said battery below 80% of a static capacity measurement of said battery performed prior to said battery test.
16. The article of claim 10 , wherein said end of test condition comprises a drop in dynamic discharge power of said battery below 70% of a dynamic power measurement of said battery performed prior to said battery test.
17. The article of claim 10 , wherein said end of test condition comprises exceeding a pre-determined testing time duration threshold.