Chongqing Jinkang Powertrain New Energy Co., Ltd.

Sf Motors, Inc.

Wenke Zhang

Ying Liu

Saeed Khaleghi Rahimian

Yifan Tang

Brennan Campbell

Jun Hou

Junzhe Shi

Sangwoo Han

Mehdi Forouzan

Chen-Yen Yu

Embodiments described herein generally relate to the modification of State of Charge (SoC) calculations within electric vehicles (EVs). A database of data points may be generated based on characteristics of a battery cell at various measured SoCs within a controlled environment. Subsequently, during the operation of an EV, a battery management system (BMS) within the EV may collect various operating data points. The collected operating data points may be utilized to reference similar data points stored in the database in order to determine an SoC value. The SoC value may be utilized to modify or alter the SoC calculations by the BMS for an EV in operation.

State of charge error estimation of battery cells background

A physics-based calendar life model for determining the state of health of a lithium ion battery cell. The model accounts for parasitic reactions on anode and cathode particles to accurately determine degradation of a battery. By incorporating electrolyte decomposition in a cathode, the present calendar model can predict capacity retention as well as the substantial rise of cell resistance at high state of charge (SOC) and temperatures. The present calendar model is a simple algorithm, utilizing only three parameters, and determines the capacity retention and resistance rise based on temperature, SOC and time.

Control-oriented physics-based calendar life model for lithium ion cells

Techniques described herein relate generally to determining and applying threshold discharging C-rates for battery cells in low temperature environments. To combat internal resistance within a battery cell at low temperature, heat may be generated within a battery cell via a high discharge C-rate. A higher discharge C-rate may cause more heat generation with a battery cell and the higher temperature may mitigate the low temperature environment. As a result of the heat generation, a battery cell's capacity may be increased. Techniques described herein may identify, for a particular low temperature (0 degrees Celsius and below), a threshold discharge C-rate that if a battery cell is discharged above the threshold, the effect of temperature rising would be more dominant than the effect of the internal resistance and more capacity would be obtained from the battery cell.

Threshold discharging C-rates for battery cells in low temperature environments

Battery health is determined by estimating a battery anode capacity, battery cathode capacity, and cyclable lithium capacity. Determining electrode and lithium capacity may include determining anode and cathode open cell voltages (OCV) at the beginning of battery life, and estimating the full cell OCV from the individual (half-cell) OCV values. Once the beginning of battery life information is known, the state of charge (SOC) for a battery is measured during battery life. The SOC measurements may be captured at a plurality of different levels. The cathode capacity, anode capacity, and cycle mobile lithium capacity are then determined from the beginning of life OCV data and plurality of SOC data. The capacities can be used to detect degradation, and a battery management system can take steps to reduce further degradation based on the capacity values.

Battery state of health estimation by tracking electrode and cyclable lithium capacities

Growing community of inventors

Santa Clara, CA, United States of America

Wenke Zhang