Integrated battery sensor for multiple battery modules

1. An automotive battery system, comprising:

a lead acid battery module configured to couple to an electrical system; and

a lithium ion battery module electrically coupled in parallel with the lead acid battery module, the lithium ion battery module comprising:

a first terminal corresponding to a positive voltage;

a second terminal and a third terminal corresponding to negative voltages, the second terminal being separate from the third terminal;

a resistor, the resistor being directly electrically coupled between the second terminal and the third terminal, and the second terminal being directly electrically coupled to a fourth terminal disposed on the lead acid battery module such that a voltage signal across the resistor is associated with a voltage of the lead acid battery module, the fourth terminal corresponding to a negative voltage; and

a control system, the control system being configured to:

receive the voltage signal associated with the resistor and associated with the voltage of the lead acid battery module; and

determine at least one of a state of charge (SOC) and a state of health (SOH) associated with the lead acid battery module based at least in part on the voltage signal.

2. The battery system of claim 1 , wherein the lead acid battery module comprises a temperature sensor configured to measure an internal temperature of the lead acid battery module.

3. The battery system of claim 2 , wherein the control system is configured to:

receive the internal temperature from the temperature sensor in the lead acid battery module; and

determine at least one of the SOC and the SOH associated with the lead acid battery module based at least in part on the internal temperature received from the lead acid battery module.

4. The battery system of claim 1 , wherein the lithium ion battery module comprises a plurality of battery cells.

5. The battery system of claim 4 , wherein the plurality of battery cells comprises at least two separate sets of battery cells electrically coupled in series with each other.

6. The battery system of claim 4 , wherein the control system is configured to:

receive data associated with the plurality of battery cells; and

determine at least one of a state of charge (SOC) and a state of health (SOH) associated with the lithium ion battery module based on the data.

7. The battery system of claim 4 , comprising an additional resistor electrically coupled between the plurality of battery cells and the third terminal.

8. The battery system of claim 1 , wherein the lithium ion battery module comprises a chemistry having a higher coulombic efficiency than the lead acid battery module.

9. The battery system of claim 1 , comprising a container that houses the lead acid battery module and the lithium ion battery module.

10. The battery system of claim 1 , comprising a battery module that houses the lithium ion battery module and comprises a fifth terminal, wherein the third terminal is directly electrically coupled to the fifth terminal.

11. A method, comprising:

receiving, via a processor comprised in a lithium ion battery module, a voltage signal associated with a resistor in the lithium ion battery module, the resistor being directly electrically coupled to between a first negative terminal and a second negative terminal comprised in the lithium ion battery module, the second negative terminal of the lithium ion battery module being directly electrically coupled to a third negative terminal comprised in a lead acid battery module such that a voltage signal across the resistor is associated with a voltage of the lead acid battery module, the lead acid battery module being electrically coupled in parallel with the lithium ion battery module; and

determining, via the processor, at least one property associated with the lead acid battery module based at least in part on the voltage signal.

12. The method of claim 11 , wherein the at least one property comprises a current being conducted through the lead acid battery module.

13. The method of claim 11 , wherein the the at least one property comprises at least one of a state of charge (SOC) and a state of health (SOH) associated with the lead acid battery module.

14. The method of claim 11 , comprising:

receiving, via the processor, a temperature measurement from a temperature sensor in the lead acid battery module; and

determining the the at least one property based at least in part on the temperature measurement.

15. A battery module for use in a vehicle, the battery module comprising:

a housing;

a first terminal, a second terminal, and a third terminal, the first terminal and the second terminal being associated with a same polarity;

a plurality of battery cells;

a first resistor electrically coupled to the plurality of battery cells and the first terminal;

a second resistor directly electrically coupled to the first resistor and directly electrically coupled between the first terminal and the second terminal, the second terminal being directly electrically coupled to a fourth terminal disposed on a separate battery module, the separate battery module being electrically coupled in parallel with the battery module; and

a control system configured to:

receive a first voltage signal associated with the first resistor and a second voltage signal, the second voltage signal being associated with the second resistor and associated with a voltage of the separate battery module; and

determine a first set of properties associated with the separate battery module based at least in part on the second voltage signal.

16. The battery module of claim 15 , wherein the plurality of battery cells comprises a plurality of lithium ion cells.

17. The battery module of claim 15 , wherein the separate battery module comprises a plurality of lead acid battery cells.

18. The battery module of claim 15 , wherein the control system is configured to determine a second set of properties associated with the battery module.

19. The battery module of claim 15 , wherein the control system is configured to receive a temperature measurement from a temperature sensor in the separate battery module and determine the first set of properties based at least in part on the temperature measurement.