Method and system for balancing a battery assembly
A system for balancing a battery assembly and related methods for making and using same are provided. The system can obtain a status of a battery assembly with a plurality of batteries. One or more of the batteries can be selected based on the obtained status, and the selected batteries can be balanced. The system, for example, can control active balancing of the selected batteries when the battery assembly is in a static state and control selective discharging of the selected batteries when the battery assembly is in a discharging state. When the battery assembly is in a charging state, selective charging of the selected batteries can be controlled. One or more cells that comprise the individual batteries alternatively can be selected for balancing. A protective circuit can help ensure safety of the balancing. Battery balancing can be energy-efficient and time-efficient. The lifetime of the battery assembly can be extended.
1. A method for balancing a battery assembly comprising a plurality of batteries in a static state, comprising:
measuring first status parameters of the plurality of batteries, each of the batteries including a plurality of cells, wherein in the static state, the battery assembly does not receive power from a power source and does not provide power to a load;
selecting a first battery and a second battery from the batteries, the first status parameters of the first battery and the second battery satisfying a first condition;
measuring second status parameters of the cells of the first battery and the cells of the second battery;
selecting, according to the second status parameters, one or more first candidate cells from the first battery that are less than the plurality of cells of the first battery, and one or more second candidate cells from the second battery that are less than the plurality of cells of the second battery; and
controlling active balancing between the one or more first candidate cells and the one or more second candidate cells, to transfer charge between the one or more first candidate cells of the first battery and the one or more second candidate cells of the second battery, wherein the controlling includes:
controlling a balancing path between the first battery and the second battery to transfer charge between the first battery and the second battery; and
isolating a particular cell of the one or more first candidate cells and the one or more second candidate cells from the balancing path upon detecting a current through the particular cell being outside a predetermined current range.
2. The method of claim 1 , wherein the plurality of cells of each of the batteries are connected in parallel and/or in series.
3. The method of claim 1 , further comprising:
isolating a particular cell of the one or more first candidate cells and the one or more second candidate cells from the balancing path upon detecting a voltage across the particular cell being outside a predetermined voltage range.
4. The method of claim 1 , wherein the first status parameters and the second status parameters comprise at least one of a voltage, a capacity, or a current.
5. The method of claim 1 , wherein the first condition comprises a difference between respective voltages across the first battery and the second battery being outside a predetermined voltage difference range.
6. The method of claim 5 , wherein the first condition comprises the difference between the respective voltages across the first battery and the second battery being greater than a predetermined voltage threshold.
7. The method of claim 1 , wherein the first condition comprises a difference between respective capacities of the first battery and the second battery being outside a predetermined capacity difference range.
8. The method of claim 7 , wherein the first condition comprises the difference between the respective capacities of the first battery and the second battery being greater than a predetermined capacity threshold.
9. The method of claim 1 , wherein the first condition comprises an expected balancing current through the first battery and the second battery being within a predetermined balancing current range.
10. The method of claim 9 , wherein the first condition comprises the expected balancing current through the first battery and the second battery being less than a predetermined current threshold.
11. The method of claim 1 , wherein the battery assembly is coupled with a battery management unit (BMU), and the controlling comprises controlling the BMU to switch to the first candidate cells and the second candidate cells for balancing.
12. The method of claim 1 , wherein the balancing path between the first battery and the second battery comprises a first path connecting positive terminals of the first battery and the second battery and a second path connecting negative terminals of the first battery and the second battery.
13. The method of claim 1 , further comprising:
measuring third status parameters of the first battery and the second battery, the third status parameters being different from the first status parameters; and
terminating the active balancing in response to the third status parameters of the first battery and the second battery satisfying a second condition;
wherein:
the first status parameters comprise at least one of a voltage, a capacity, or a current, and
the third status parameters are different from the first status parameters and comprise at least another one of the voltage, the capacity, or the current.
14. A system for balancing a battery assembly comprising a plurality of batteries in a static state, comprising:
one or more processors individually or collectively configured to:
measure first status parameters of the plurality of batteries, each of the batteries including a plurality of cells, wherein in the static state, the battery assembly does not receive power from a power source and does not provide power to a load;
select a first battery and a second battery from the batteries; the first status parameters of the first battery and the second battery satisfying a first condition;
measure second status parameters of the cells of the first battery and the cells of the second battery;
select, according to the second status parameters, one or more first candidate cells from the first battery that are less that the plurality of cells of the first battery, and one or more second candidate cells from the second battery that are less than the plurality of cells of the second battery; and
control active balancing between the one or more first candidate cells and the one or more second candidate cells, to transfer charge between the one or more first candidate cells of the first battery and the one or more second candidate cells of the second battery wherein the one or more processors further configured to:
control a balancing path between the first battery and the second battery to transfer charge between the first battery and the second battery; and
isolate a particular cell of the one or more first candidate cells and the one or more second candidate cells from the balancing path upon detecting a current through the particular cell being outside a predetermined current range.
15. The system of claim 14 , wherein the first condition comprises an expected balancing current through the first battery and the second battery being within a predetermined balancing current range.
16. The system of claim 15 , wherein the first condition comprises the expected balancing current through the first battery and the second battery being less than a predetermined current threshold.
17. An apparatus for battery balancing in a static state, comprising:
a battery assembly comprising a plurality of batteries, each of the batteries including a plurality of cells, wherein in the static state, the battery assembly does not receive power from a power source and does not provide power to a load; and
a system coupled with the batteries and comprising one or more processors individually or collectively configured to:
measure first status parameters of the plurality of batteries;
select a first battery and a second battery from the batteries, the first status parameters of the first battery and the second battery satisfying a first condition;
measure second status parameters of the cells of the first battery and the cells of the second battery;
select, according to the second status parameters, one or more first candidate cells from the first battery that are less than the plurality of cells of the first battery, and one or more second candidate cells from the second battery that are less than the plurality of cells of the second battery; and
control active balancing between the one or more first candidate cells and the one or more second candidate cells, to transfer charge between the one or more first candidate cells of the first battery and the one or more second candidate cells of the second battery, wherein the one or more processors further configured to:
control a balancing path between the first battery and the second battery to transfer charge between the first battery and the second battery; and
isolate a particular cell of the one or more first candidate cells and the one or more second candidate cells from the balancing path upon detecting a current through the particular cell being outside a predetermined current range.