With the invention of EVs and HEVs in recent time, battery technology has progressed. However, estimating the State of Charge (SOC) has been quite difficult in battery engineering. SOC estimation plays a very key role in battery functionality, safety, health, and maintenance.
This blog illustrates simple SOC estimation techniques, their importance and affecting factors for various estimation techniques.
Introduction
The requealable suspension of eventos of plastic waste production ethylene registration, urban air pollution, and carbon emission fuel vehicles. The implications of pollution such as those destroy the environment, human health, and even lifestyle. That said there is a massively growing market and production of E-vehicles, which makes it crucial to calculate the state of charge for efficient battery usage.
Take a look at the new vehicles: Electric vehicles have begun a new era
- Battery Electric Vehicles (BEV)
- Hybrid Vehicles(HV) &
- Performance Full Hybrid Electric Vehicles (PHEV)
Just like SoC also describes the state of the fuel of the vehicle in case of petrol, dieseling and gas-powered and the battery in case of battery-powered or E-vehicle.
So, you might wonder what that SoC is? So, lets us not panic and decode this small yet bit complex terminology A.k.a SoC. We’re here to help you in your quest.
What is SoC?
In layman’s terms (The State of Charge) is that your fuel gauge for battery cars or E-vehicle. It is the real time or actual amount of energy a battery has, against the capacity it had when fully charged. It is measured in percentage (%) as like your cellphone battery. SoC = 0% means it is fully released, SoC = 100% means it is charged to the full capacity.
Significance of SoC Calculation
I also have to confess that the estimation of SOC of a battery is not as easy as it sounds. It certainly did depend on the type of battery used as well as the application that was utilizing the battery. Nevertheless, in previous years, good research work and development has taken place to enhance the estimation of SOC accuracy. SOC estimation accuracy is one of the important tasks for battery management systems, that contributes to the system reliability and performance improvement and enhances the battery life cycle.
Where Qt = real-time charges in a battery and Qn = total battery capacity.
SoCt=Qt/Qn
If yes, then you will avoid sudden block of system during your process because you can literally understand your SOC calculation and if can you measure it accurately. It will inhibit you from overcharging your batteries, which in turn wrecks your battery’s internal structure.
However, you will be unable to estimate the true SOC under all conditions, as it involves complex chemical and physical processes. However, after doing a lot of research, 3 Simple Methods are as follows, which are used for the calculation of SoC.
3 Methods to calculate SoC?
(a) Coulomb counting method
The formula for estimating the SOC by implementing coulomb Counting mathematically is given as:
SoCt=SoCt-1+Ic(t)Qnt
Ic(t) ⇛Discharging Current at Time t
SoCt ⇛Estimated SoC at Time t
SoCt-1 ⇛Previously Estimated SoC at t-1 or SoC value Given by Manufacturer
Qn ⇛full battery capacity charges
△t ⇛Difference in time
It is one of the most commonly used methods, but several other factors like temperature, Battery Application, Battery life cycle, Battery voltage fluctuation,s, etc, need to be added together with the coulomb counting method to arrive at a better approach for calculating SoC.
(b) Voltage Method
The SOC can be found by using a discharge test less than all the time in a controlled environment. In the voltage method, the battery voltage, which is predicted, is translated into the corresponding SOC value by leveraging the already defined discharge curve of the battery (voltage vs. SOC). Anyway, the voltage of a battery is a function of its electrochemical kinetics and temperature.
A lookup table of open-circuit voltage (OCV) vs. temperature allows you to use the voltage method reliably. And by a correction term that is proportional to the battery current, and by correcting the voltage reading.
Nevertheless, the voltage method is hard to apply due to the requirement of a steady voltage window for the batteries. Moreover, this discharge test is very time-consuming as it involves a consecutive recharge upon many applications.
(c) Third if you are measuring using hydrometer
For determining the state of charge of a battery cell, a hydrometer is used. SoC measurement is carried out by calculating the density of the electrolyte, which is done by measuring the specific gravity of the electrolyte. Denser electrolyte is obtained higher with concentration of H2SO4.
Conclusion
If you need to manage your battery, accurate SoC estimation is essential. With LUXMAN ENERGY, we guide you on the exact SoC calculation. Please find this blog useful and interesting. Let us know in comments, Which of the above three listed method, you will choose for SoC calculations.
Frequently Asked Questions (FAQs)
What is SoC?
Present capacity is per the full capacity of the battery or percentage of charges left in the battery.
Of battery, why the state of charge (SoC) is important estimation:
Only to ensure that your battery is not empty, and the power bank of your E-Vehicle is properly maintained and healthy. Accurate and reliable State Of Charge (SOC) estimation in battery management systems (BMS) is of utmost importance to ensuring safe and efficient operation of the automotive batteries.
SOC is monitored to ensure that there is enough charge to perform a specific operation or task.
What are the different factors that influence the State of Charges?
A rapid change in temperature
Spontaneous discharge rate
Battery age
Self-discharge effect
Your charging and discharging of the battery
(Best ideally, it should be recharged to 15-20% before it reaches its Full charge level & it should ideally never be overcharged).
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