Abstract

This paper proposes a smart lithium-ion battery capacity estimation method for electric bicycles. Battery capacity information informs the electric vehicle driver of the residual battery working time, thus facilitating the estimation of mileage of electric bicycle and timing of battery charging to avoid overcharging or over-discharging. Factors such as different discharge rates, environmental temperature, battery charge and discharge efficiency and battery aging affect the released capacity of battery, which is an electrochemical reaction of battery. In addition to integrating the advantages of the coulometric measurement and open circuit voltage measurement methods, and the proposed smart lithium-ion battery capacity estimator also incorporates discharge current, temperature, battery aging, as well as charging efficiency factors into capacity correction to develop a highly accurate PIC single-chip lithium-ion battery capacity estimation system.

Highlights

  • Despite their convenience in modern life, automotive vehicles operate on fuel oil, emitting carbon dioxide that poses a threat to human health, exacerbates the greenhouse effect and contributes to global warming

  • The open circuit voltage method is quite feasible for estimating the initial capacity of batteries

  • The output voltage of a lithium-ion battery is initially reduced to 1/10 time in order to allow the output range of voltage measurement circuit to be 2.5~4.2V; 2.5V is deducted through the operational amplifier; and the voltage is amplified for the input voltage range of 0~5V of the A/D converter

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Summary

Introduction

Despite their convenience in modern life, automotive vehicles operate on fuel oil, emitting carbon dioxide that poses a threat to human health, exacerbates the greenhouse effect and contributes to global warming. Multiplying the battery residual capacity (Wh) with the energy consumption factor of an electric vehicle (km/Wh) allows drivers to accurately predict the mileage of electric vehicles based on the current battery capacity [1,2,3]. Estimating the battery capacity further allows electric vehicle drivers to avoid battery overcharging and over-discharging in order to extend the battery service life. Lithium-ion batteries in electric bicycles significantly differ from those in other products such as mobile phones, notebook computers and uninterruptible power supply systems. Coulometric measure-ment allows us to estimate the battery capacity accurately, it generates a large accumulative error if used for a long period of time. Precisely estimating the lithium-ion battery capacity involves consideration of the current effect, battery temperature, battery aging and charging efficiency

Lithium-ion Battery
Chargers and Renewable Energy Design
Solar Power System
Regenerative Brake Power System
Wireless Charging System
A Smart Battery Capacity Estimation System
Open Circuit Voltage Method
Coulometric Measuring Method
Additive Effect of Current
Battery Aging Effect
Temperature
Experimental Results
Constant Discharge Current Test
Dynamic Discharge Current Test
Conclusions
Full Text
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