Techniques for enhanced battery pack recharging
View Patent ↗A method includes detecting that a battery pack requires charging and is currently operable for recharging. The method can identify a specific cell having a highest voltage in response to the detecting. The method can then recharge each cell of the battery pack to a predetermined voltage that is a sum of (i) a maximum open circuit voltage of the specific cell and (ii) a voltage based on a resistance of and a first current supplied to the specific cell. When a temperature of the specific cell is less than a predetermined temperature or an age of the specific cell is greater than a predetermined age, the method includes recharging each cell to the predetermined voltage at less than the first current when (i) a predetermined period has elapsed or (ii) a voltage of the specific cell is less than a voltage threshold.
1. A method, comprising:
detecting, at a controller of an electric vehicle, the controller including one or more processors, that (i) a battery pack of the electric vehicle requires recharging and (ii) the battery pack is currently operable to be recharged by an external charging unit, the battery pack including a plurality of cells;
identifying, at the controller, a specific cell of the plurality of cells that has a highest voltage in response to the detecting; and
commanding, by the controller, the external charging unit to recharge each cell of the battery pack to a predetermined voltage that is a sum of (i) a maximum open circuit voltage of the specific cell and (ii) a voltage based on a resistance of the specific cell and a first current supplied to the specific cell.
2. The method of claim 1 , further comprising:
determining, at the controller, at least one of a temperature of the specific cell and an age of the specific cell; and
selectively commanding, by the controller, the external charging unit to adjust a current supplied to each cell of the battery pack based on at least one of the temperature of the specific cell and the age of the specific cell.
3. The method of claim 2 , wherein the controller selectively commands the external charging unit to supply zero current to each cell of the battery pack based on at least one of the temperature of the specific cell and the age of the specific cell.
4. The method of claim 3 , wherein selectively commanding the external charging unit to adjust the current supplied to each cell of the battery pack includes commanding, by the controller, the external charging unit to decrease the current supplied to each cell to less than the first current when the temperature of the specific cell is less than a first predetermined temperature.
5. The method of claim 3 , wherein selectively commanding the external charging unit to adjust the current supplied to each cell of the battery pack includes commanding, by the controller, the external charging unit to decrease the current supplied to each cell to less than the first current when the age of the specific cell is greater than a first predetermined age.
6. The method of claim 2 , further comprising commanding, by the controller, the external charging unit to recharge each cell of the battery pack to the predetermined voltage at a second current that is less than the first current when (i) a predetermined period has elapsed or (ii) a voltage of the specific cell is less than a voltage threshold.
7. The method of claim 6 , further comprising determining, at the controller, whether (i) the temperature of the specific cell is less than a second predetermined temperature that is less than the first predetermined temperature or (ii) the age of the specific cell is greater than a second predetermined age that is greater than the first predetermined age.
8. The method of claim 6 , further comprising commanding, by the controller, the external charging unit to decrease the current supplied to each cell of the battery pack to less than the second current when the temperature of the specific cell is less than the second predetermined temperature or the age of the specific cell is greater than the second predetermined age.
9. The method of claim 8 , wherein the controller commands the external charging unit to supply zero current to each cell of the battery pack when the temperature of the specific cell is less than the second predetermined temperature or the age of the specific cell is greater than the second predetermined age.
10. The method of claim 8 , further comprising commanding, by the controller, the external charging unit to recharge each cell of the battery pack to the predetermined voltage at a third current that is less than the second current when (i) the predetermined period has elapsed or (ii) the voltage of the specific cell is less than the voltage threshold.
11. The method of claim 10 , wherein the predetermined period has a duration such that the external charging unit is able to recharge each cell of the battery pack to the predetermined voltage using the second or third currents.
12. The method of claim 2 , further comprising estimating, at the controller, the age of the specific cell based on a resistance of the specific cell.
13. The method of claim 12 , further comprising:
estimating, at the controller, a state of health (SOH) of the specific cell by dividing the resistance of the specific cell by a resistance of the specific cell at a beginning of its life to obtain an estimated SOH; and
estimating, at the controller, the age of the specific cell based on the estimated SOH.
14. The method of claim 13 , wherein the age of the specific cell is estimated based on the estimated SOH by calculating:
AGE=(300%/SOH R )−200%
where AGE represents the age of the specific cell as a percentage of full life and SOH R represents the estimated SOH.
15. The method of claim 1 , further comprising determining, at the controller, the predetermined voltage using a look-up table that includes varying predetermined values for the predetermined voltage based on various values for the first current.
16. A method, comprising:
detecting, at a controller of an electric vehicle, the controller including one or more processors, that (i) a battery pack of the electric vehicle requires recharging and (ii) the battery pack is currently operable to be recharged by an external charging unit, the battery pack including a plurality of cells;
identifying, at the controller, a specific cell of the plurality of cells that has a highest voltage in response to the detecting;
commanding, by the controller, the external charging unit to recharge each cell of the battery pack to a predetermined voltage that is a sum of (i) a maximum open circuit voltage of the specific cell and (ii) a voltage based on a resistance of the specific cell and a first current supplied to the specific cell;
determining, at the controller, a temperature of the specific cell and an age of the specific cell;
determining, at the controller, that the recharging of each cell of the battery pack is complete when the temperature is greater than or equal to a first predetermined temperature and the age is less than or equal to a first predetermined age;
commanding, by the controller, the external charging unit to decrease a current supplied to each cell of the battery pack to zero when the temperature is less than the first predetermined temperature or the age is greater than the first predetermined age;
determining, at the controller, that the recharging of each cell of the battery pack is complete when a voltage of the specific cell is greater than or equal to a voltage threshold; and
commanding, by the controller, the external charging unit to recharge each cell of the battery pack to the predetermined voltage at a second current that is less than the first current when a predetermined period has elapsed or the voltage of the specific cell is less than the voltage threshold.
17. The method of claim 16 , further comprising determining, at the controller, whether (i) the temperature of the specific cell is less than a second predetermined temperature that is less than the first predetermined temperature or (ii) the age of the specific cell is greater than a second predetermined age that is greater than the first predetermined age.
18. The method of claim 16 , further comprising commanding, by the controller, the external charging unit to decrease the current supplied to each cell of the battery pack to zero when the temperature of the specific cell is less than the second predetermined temperature or the age of the specific cell is greater than the second predetermined age.
19. The method of claim 18 , further comprising commanding, by the controller, the external charging unit to recharge each cell of the battery pack to the predetermined voltage at a third current that is less than the second current when (i) the predetermined period has elapsed or (ii) the voltage of the specific cell is less than the voltage threshold.
20. The method of claim 16 , further comprising determining, at the controller, the predetermined voltage using a look-up table that includes varying predetermined values for the predetermined voltage based on various values for the first current.