How to make a battery level indicator, battery charger, 18650, 12V, electronics
we will show you how to make a battery level indicator and a battery charger. These electronic projects are simple and easy to make and will help you track your battery level with simple and easy to understand symbols!
If you're looking to learn how to make electronic projects, then this video is for you! We'll show you how to make a battery level indicator and a battery charger, both of which are simple to make and will help you track your battery level in an easy-to-understand way. With these projects, you will be able to stay informed about your battery status and ensure that you are always using your electronic devices safely.
SoC measurement of a Lithium Ion battery:
There are several ways to measure the state of charge (SoC) or the depth of discharge (DoD) of a battery. Some methods require sometimes complex equipment (impedance spectroscopy or hydrometry measurement for lead batteries). These methods are beyond the scope of this article.
In this article, we will present the 2 most common methods to estimate the state of charge (SoC) of a battery: OCV method (Open Circuit Voltage or Open Circuit Voltage) and Coulometric method.
1/ State of charge (SoC) measurement by OCV method (Open Circuit Voltage)
All types of batteries have one thing in common: the voltage at their terminal decreases or increases depending on their level of charge. The voltage will be maximum when the battery is fully charged and minimum when it is empty.
This relationship between voltage and SOC is directly dependent on the battery technology used. As an example, the diagram below compares the discharge curves between a 48V lead-acid battery and its Lithium Iron Phosphate (LiFePO4) equivalent.
It can be seen that lead-acid batteries have a relatively linear curve, which allows a good estimate of the state of charge: for a measured voltage, it is possible to estimate the associated SoC value quite precisely.
On the other hand, Lithium-ion batteries have a much "flatter" discharge curve, this means that for a wide operating range, the voltage at the battery terminals changes very little.
Lithium Iron Phosphate (LiFePO4) technology has the flattest discharge curve, which makes it very difficult to estimate the SoC on a simple voltage measurement. Indeed, the voltage difference is so small between two charge levels that it is not possible to estimate the state of charge with great precision.
2/ State of charge (SoC) measurement by Coulomb counter
To follow the state of charge during the use of the battery, the most intuitive method consists in following the current by integrating it during the use of the cells. This integration directly gives the quantity of electrical charges injected or withdrawn from the battery, thus making it possible to precisely quantify the SoC of the battery.
Unlike the OCV method, this method is able to determine the evolution of the state of charge during the use of the battery. It does not require the battery to be at rest to perform an accurate measurement.
Although the current measurement is performed by a precision resistor, small measurement errors occur, linked to the sampling frequency of the measurement. To correct for these marginal errors, the Coulomb counter is automatically recalibrated at each charge cycle.
SoC measurements made by coulomb counting allow a measurement error of less than 1%, which allows a very precise indication of the energy remaining in the battery. Unlike the OCV method, coulomb counting is independent of power fluctuations delivered by the battery (which cause battery voltage drops), and the accuracy remains constant whatever the use of the battery.
How to make a battery level indicator, battery charger, 18650, 12V, electronics
we will show you how to make a battery level indicator and a battery charger. These electronic projects are simple and easy to make and will help you track your battery level with simple and easy to understand symbols!
If you're looking to learn how to make electronic projects, then this video is for you! We'll show you how to make a battery level indicator and a battery charger, both of which are simple to make and will help you track your battery level in an easy-to-understand way. With these projects, you will be able to stay informed about your battery status and ensure that you are always using your electronic devices safely.
SoC measurement of a Lithium Ion battery:
There are several ways to measure the state of charge (SoC) or the depth of discharge (DoD) of a battery. Some methods require sometimes complex equipment (impedance spectroscopy or hydrometry measurement for lead batteries). These methods are beyond the scope of this article.
In this article, we will present the 2 most common methods to estimate the state of charge (SoC) of a battery: OCV method (Open Circuit Voltage or Open Circuit Voltage) and Coulometric method.
1/ State of charge (SoC) measurement by OCV method (Open Circuit Voltage)
All types of batteries have one thing in common: the voltage at their terminal decreases or increases depending on their level of charge. The voltage will be maximum when the battery is fully charged and minimum when it is empty.
This relationship between voltage and SOC is directly dependent on the battery technology used. As an example, the diagram below compares the discharge curves between a 48V lead-acid battery and its Lithium Iron Phosphate (LiFePO4) equivalent.
It can be seen that lead-acid batteries have a relatively linear curve, which allows a good estimate of the state of charge: for a measured voltage, it is possible to estimate the associated SoC value quite precisely.
On the other hand, Lithium-ion batteries have a much "flatter" discharge curve, this means that for a wide operating range, the voltage at the battery terminals changes very little.
Lithium Iron Phosphate (LiFePO4) technology has the flattest discharge curve, which makes it very difficult to estimate the SoC on a simple voltage measurement. Indeed, the voltage difference is so small between two charge levels that it is not possible to estimate the state of charge with great precision.
2/ State of charge (SoC) measurement by Coulomb counter
To follow the state of charge during the use of the battery, the most intuitive method consists in following the current by integrating it during the use of the cells. This integration directly gives the quantity of electrical charges injected or withdrawn from the battery, thus making it possible to precisely quantify the SoC of the battery.
Unlike the OCV method, this method is able to determine the evolution of the state of charge during the use of the battery. It does not require the battery to be at rest to perform an accurate measurement.
Although the current measurement is performed by a precision resistor, small measurement errors occur, linked to the sampling frequency of the measurement. To correct for these marginal errors, the Coulomb counter is automatically recalibrated at each charge cycle.
SoC measurements made by coulomb counting allow a measurement error of less than 1%, which allows a very precise indication of the energy remaining in the battery. Unlike the OCV method, coulomb counting is independent of power fluctuations delivered by the battery (which cause battery voltage drops), and the accuracy remains constant whatever the use of the battery.
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