State of charge sensing for a mixed chemistry battery

Patent metadata

Field	Value
Publication number	US-12392834-B2
Application number	US-202217743524-A
Country	US
Kind code	B2
Filing date	May 13, 2022
Priority date	May 13, 2022
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A mixed chemistry battery including a sensing cell having a first chemistry, a battery cell having a second chemistry that is different than the first chemistry, where the battery cell is connected to the sensing cell in series. The mixed chemistry battery also includes a battery monitoring system configured to monitor a current flow through the sensing cell and the battery cell and to calculate a state-of-charge (SOC) of the sensing cell. The battery monitoring system is further configured to calculate a SOC of the battery cell based at least in part on the SOC of the sensing cell.

First claim

What is claimed is:

1. A mixed chemistry battery comprising:
a sensing cell having a first chemistry, wherein the first chemistry has a state-of-charge (SOC) that varies distinctly by an open-circuit voltage (OCV) level of the sensing cell;
a battery cell having a second chemistry that is different than the first chemistry, the second chemistry has a SOC that does not vary distinctly by an OCV level of the battery cell, wherein the battery cell is connected to the sensing cell in series; and
a battery monitoring system configured to monitor a current flow through the sensing cell and the battery cell and to calculate a state-of-charge (SOC) of the sensing cell based on a current flows through the sensing cell, the battery monitoring system including at least one sensor configured to measure an open circuit voltage (OCV) of the sensing cell, an OCV of the battery cell and a current flowing through the sensing cell and the battery cell,
wherein the battery monitoring system is further configured to calculate a SOC of the battery cell based at least in part on the SOC of the sensing cell, the calculation being according to

SOC
BC

=

SOC
SC

-
d
+

(

1
-

S
⁢
%

100
⁢
%

)

⁢

∫
idt

CAP
BC

,

 where SOC BC is the SOC of the battery cell, SOC SC is the SOC of the sensing cell, d is the minimum offset value and

(

1
-

S
⁢
%

100
⁢
%

)

⁢

∫
idt

CAP
BC

 is the scaling value, with S being the scaling factor, CAP BC being the capacity of the battery cell and i the current through the battery cell;
the mixed chemistry battery being an electric vehicle battery, the battery monitoring system being a vehicle battery monitoring system, and wherein the battery monitoring system is configured to respond to the electric vehicle being at rest for at least a threshold amount of time by resetting the calculated SOC of the sensing cell based on a sensing cell SOC curve;
wherein the capacity of the battery cell is equal to the capacity of the sensing cell multiplied by the scaling factor, which has a value of less than one; and
wherein the scaling factor is calculated by subtracting the minimum offset value and a maximum offset value from one, wherein the minimum offset value is determined based on a minimum SOC level at which accurate sensing may be provided by the sensing cell.

2. The mixed chemistry battery of claim 1 , wherein the first chemistry is nickel-manganese cobalt and the second chemistry is lithium iron phosphate.

3. The mixed chemistry battery of claim 1 , wherein the SOC of the sensing cell is calculated using a combination of coulomb counting method and a Kalman filter method, and an open-circuit voltage (OCV) inverse lookup method.

4. The mixed chemistry battery of claim 1 , wherein the minimum offset value is determined based on a minimum SOC level at which accurate sensing may be provided by the sensing cell.

5. The mixed chemistry battery of claim 1 , wherein based on a determination that the SOC of the sensing cell is one of below a minimum threshold value and above a maximum threshold value, the battery monitoring system is further configured to measure an open circuit voltage of the sensing cell and the battery cell during a commanded rest of a vehicle containing the mixed chemistry battery.

6. The mixed chemistry battery of claim 5 , wherein the battery monitoring system is further configured to calculate the SOC of the sensing cell based on the open circuit voltage of the sensing cell and to calculate the SOC of the battery cell based on the open circuit voltage of the battery cell.

7. The mixed chemistry battery of claim 1 , wherein based on a determination that the SOC of the sensing cell is above a maximum threshold value, the battery monitoring system is configured to calculate a degradation factor for at least one of the battery cell and the sensing cell based on a change in a capacity of the at least one of the battery cell and the sensing cell.

8. The mixed chemistry battery of claim 1 , wherein the battery monitoring system is further configured to calculate the SOC of the battery cell based at least in part on the SOC of the sensing cell while the battery cell is being utilized.

9. A method for determining a state-of-charge (SOC) of a battery cell of a mixed chemistry battery, the method comprising:
measuring an open circuit voltage (OCV) of a sensing cell, measuring an OCV of a battery cell, and measuring a current passing through the sensing cell and the battery cell using at least one sensor of a battery monitoring system;
calculating a SOC of the sensing cell connected to the battery cell in series, wherein the sensing cell has a first chemistry and the battery cell has a second chemistry that is different than the first chemistry; wherein the first chemistry has a state-of-charge (SOC) that varies distinctly by the open-circuit voltage (OCV) level of the sensing cell and the second chemistry has a SOC that does not vary distinctly by an OCV level of the battery cell; and
calculating an SOC of battery cell according to

SOC
BC

=

SOC
SC

-
d
+

(

1
-

S
⁢
%

100
⁢

Assignees

• Gm Global Tech Operations Llc

Inventors

• Wang Yue-Yun
• Zhao Junfeng

Classifications

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M10/054 Primary

  Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium · CPC title

• G01R31/3648

  comprising digital calculation means, e.g. for performing an algorithm · CPC title

• H01M10/4257

  Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries · CPC title

• G01R31/382

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title