Apparatus, system and method for charge balancing of individual batteries in a string of batteries using battery voltage and temperature, and detecting and preventing thermal runaway
Implementations of the present disclosure involve a system and method for load balancing a string of jars. The temperature and voltage of each jar is measured and a target voltage for the jar is set based on the measured temperature. A current is supplied to the jar in order to maintain, increase, or decrease the jar's voltage.
1. A method of load balancing comprising:
measuring a first voltage and a first temperature of a first battery in a string of batteries;
measuring a second voltage and a second temperature of a second battery in the string of batteries;
setting a first target voltage based on a first nominal battery voltage associated with the first temperature;
setting a second target voltage based on a second nominal battery voltage associated with the second temperature;
controlling a first current to the first battery to:
maintain the first voltage when the first voltage is at the first target voltage;
increase the first voltage when the first voltage is below the first target voltage; and
decrease the first voltage when the first voltage is above the first target voltage; and
controlling a second current to the second battery to:
maintain the second voltage when the second voltage is at the second target voltage;
increase the second voltage when the second voltage is below the second target voltage; and
decrease the second voltage when the second voltage is above the second target voltage.
2. The method of claim 1 , wherein controlling the first current to the first battery comprises controlling a current bypass circuit operably coupled to the first battery, wherein the current bypass circuit receives a bypass current being supplied to charge the string of batteries and routes a third current to bypass the first battery with a remainder of the bypass current being supplied to the first battery as the first current.
3. The method of claim 1 , wherein the controlling of the first current to the first battery further comprises:
reducing the first current when the first temperature exceeds a first temperature threshold indicative of thermal runaway, disregarding the first target voltage, and thereby reducing the first temperature.
4. The method of claim 3 , wherein the controlling of the second current to the second battery further comprises:
reducing the second current being provided to the second battery in the string of batteries when the first temperature exceeds the first temperature threshold, disregarding the second target voltage, thereby reducing the second temperature of the second battery.
5. The method of claim 3 , further comprising generating an alert when the first temperature meets the first temperature threshold indicative of thermal runaway.
6. The method of claim 1 , further comprising determining whether the first battery is malfunctioning by:
storing the first temperature and first voltage in a memory; and
generating an alert indicating that the first battery is near failure when at least one of:
the first temperature of the first battery has a temperature exceeding a first temperature threshold;
the first current exceeds a current threshold; and
the first voltage is less than a third voltage indicative of the first battery malfunctioning.
7. The method of claim 1 , further comprising sending the first temperature and the first voltage to a remote computing device.
8. The method of claim 2 , further comprising calculating the first current by subtracting the bypass current from the third current being supplied to the string of batteries and sending a value of the first current to a remote computing device.
9. A load balancing system comprising:
a first battery monitor operably coupled to a first battery in a string of batteries the first battery monitor recording a first voltage and a first temperature of the first battery;
a second battery monitor operably coupled to a second battery in the string of batteries, the second battery monitor recording a second voltage and a second temperature of the second battery;
a controller configured to receive the first voltage and the first temperature from the first battery monitor, and further configured to receive the second voltage and the second temperature from the second battery monitor, wherein the controller:
sets a first target voltage for the first battery based on a first nominal battery voltage associated with the first temperature;
sets a second target voltage for the second battery based on a second nominal battery voltage associated with the second temperature;
controls a first current supplied to the first battery using a first bypass circuit to:
maintain the first voltage when the first voltage is at the first target voltage;
increase the first voltage when the first voltage is below the first target voltage; and
decrease the first voltage when the first voltage is above the first target voltage; and
controls a second current supplied to the second battery using a second bypass circuit to:
maintain the second voltage when the second voltage is at the second target voltage;
increase the second voltage when the second voltage is below the second target voltage; and
decrease the second voltage when the second voltage is above the first target voltage.
10. The load balancing system of claim 9 , wherein the controller is further configured to determine a bypass current for charging the first battery and the second battery via a bypass circuit.
11. The load balancing system of claim 10 , wherein a third current is routed through a first portion of the bypass circuit with a first remainder portion of the bypass current being supplied to the first battery; and
a fourth current is routed through a second portion of the bypass circuit with a second remainder portion of the bypass current being supplied to the second battery.
12. The load balancing system of claim 11 , wherein the controller is configured to provide a pulse width modulated signal to the first portion of the bypass circuit to control the third current.
13. The load balancing system of claim 9 , wherein the controller comprises a memory configured to store charge balancing metrics including each measured temperature and voltage and the controller is further configured to generate an alert when at least one of:
the first temperature exceeds a first temperature threshold;
the first current exceeds a current threshold; and
the first voltage is less than a third voltage indicative of the first battery malfunctioning.
14. The load balancing system of claim 9 , wherein the controller further comprises a network interface configured to send the first temperature and the first voltage to a remote computing device.
15. The load balancing system of claim 9 , wherein the controller is further configured to reduce the first current when the first temperature exceeds a first temperature threshold, disregarding the first target voltage and thereby reducing the first temperature.
16. The load balancing system of claim 15 , wherein the controller is further configured to reduce the second current to the second battery when the first temperature exceeds the first temperature threshold.
17. A method of load balancing comprising:
measuring a first voltage and a first temperature of a first battery in a string of batteries;
setting a first target voltage based on a first nominal battery voltage associated with the first temperature;
obtaining a first current based on a difference between the first voltage and the first target voltage;
measuring a second voltage and a second temperature of a second battery in the string of batteries;
setting a second target voltage based on a second nominal battery voltage associated with the second temperature;
obtaining a second current based on a difference between the second voltage and the second target voltage;
obtaining a third current that is greater than or equal to a larger of the first current and the second current;
controlling the first current to maintain the first voltage when the first voltage is at the first target voltage, increase the first voltage when the first voltage is below the first target voltage, and decrease the first voltage when the first voltage is above the first target voltage by routing a first portion of the third current from the first battery using a first bypass circuit operably coupled to the first battery; and
controlling the second current to maintain the second voltage when the second voltage is at the second target voltage, increase the second voltage when the second voltage is below the second target voltage, and decrease the second voltage when the second voltage is above the second target voltage by routing a second portion of the third current from the second battery using a second bypass circuit operably coupled to the second battery.
18. The method of claim 17 , further comprising reducing the first current when the first temperature exceeds a first temperature threshold thereby reducing the first temperature.
19. The method of claim 18 , further comprising reducing the second current when the first temperature exceeds a second temperature threshold.