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Battery State Of Charge-Calculation, Definition And Percentage

The charging state (SOC) of the cell means the capacity currently available depending on the nominal capacity. The SOC value varies between 0% and 100%. When SOC is 100%, the cell is said to be filled, while SOC 0% indicates that the cell is completely depleted. In practical applications, the SOC cannot exceed 50% and therefore the cells will refill when the SOC reaches 50%. Likewise, the maximum SOC begins to decrease as the cell ages. This means that for mature cells, 100% SOC corresponds to 75% -80% SOC per new cell.

The determination of SoC depends on cell chemistry. In most cellular chemicals, the reversible voltage of a cell depends on the SoC. The difference in voltage between a fully charged and an empty cell can be more than 0.5 V. The cell voltage (open circuit or low charge and discharge currents) is a useful measure for SoCs.

For chemicals with low-stress dependence on SoCs, techniques such as coulomb counting should be used. If a lithium-ion battery frequently fails to discharge and recharge completely (deep cycle), recalibration of an external electronic manometer, such as an SoC meter, may require a deep cycle after approximately every thirty charges to prevent incorrect battery displays. Load.

In this article, we propose and compare algorithms for assessing the state of charge (SOC) and health (SOH) of battery management systems. This algorithm is based on batteries designed specifically for light electric vehicles (electric scooters or bicycles). A sophisticated battery management system has been developed to assess the instantaneous charge available in a battery while tracking slowly changing battery aging parameters.

Two algorithms have been proposed for SOC estimation: extended Kalman filter (EKF) and adaptive extended Kalman filter (AEKF). In the adaptive version of the Kalman filter, the correct model noise covariance values ??are adaptively adjusted using information from the online innovation analysis. In the second part of this article, we propose a new least-squares estimation algorithm for estimating the SOH of a battery. A common basis for a combined SOC / SOH assessment was discussed.

## How do you figure out the battery percentage?

To keep a close eye on your device's battery life, it's important to display your Android battery percentage along with a default icon. If you use your smartphone or tablet during the day, as we do, turn on the battery percentage to see exactly how much power you have left while using the device. Fortunately, the instructions for checking the battery level are not complicated. This tutorial will show you how to activate the battery percentage of your Android smartphone or tablet.

What is the correct formula for calculating the battery charge percentage depending on the type of battery (12 V, 24 V, 48 V, etc.) and the current battery voltage? For example, if I have a 12 V battery and the battery still contains 12.06 V, I have about 50% capacity

Terminal Voltage Method

The terminal voltage method is based on the drop in terminal voltage due to the internal impedance when the battery is discharged, so that the electromotive force (EMF) of the battery is proportional to the terminal voltage. Since the EMF of a battery is roughly proportional to the SOC, the final voltage of the battery is also roughly directly proportional to the SOC.

The terminal voltage method is used at different discharge currents and temperatures. However, at the end of battery discharge, the estimated terminal voltage method error is large because the voltage at the battery terminals drops suddenly at the end of discharge.

Impedance Method

Among the techniques used, impedance measurement provides insight into several parameters, the value of which may depend on the battery charge state. Although the impedance parameter and its variation with charge state are not specific for all battery systems, it seems necessary to carry out various impedance experiments to identify and use the impedance parameter to estimate the battery charge state.

Impedance Spectroscopy Method

The impedance spectroscopy method measures the impedance of a battery at various variable frequencies with different charging and discharging currents. The impedance value of the model is determined by the least square, which is adjusted to the measured impedance value. SOC can be performed indirectly by measuring the impedance of the battery current and connecting it to a known impedance at different SOC levels.

Accounting Valuation

The current battery discharge data is used as input in the calculation method. This method allows you to consider some of the internal effects of the battery, such as B. Self-discharge, capacity loss, and discharge efficiency. Two types of valuation methods are used for accounting: the Coulomb method of calculation and the modified Coulomb method of calculation.

Voltage Method

Measuring charge level by voltage is easy, but can be inaccurate as the cell material and temperature affect the voltage. The most obvious SoC voltage failure occurs when the battery is damaged by charging or discharging. The resulting excitation distorts the voltage and is no longer a suitable reference to the SoC. To obtain an accurate reading, the battery must be in standby mode for at least 4 hours. Battery manufacturers recommend using lead within 24 hours. This makes voltage-based SoC processes impractical for batteries in active mode. Each battery chemical has its disposal label. Voltage-based SoCs perform relatively well with inactive lead-acid batteries, but the voltage method is not possible due to the flat discharge curves of nickel and lithium batteries. It is very flat and 80% of the stored energy remains in a flat voltage profile.