Battery State of Charge Calculator

Batteries make the power source for almost everything that needs a portable power supply. When using a battery, we cannot tell how long it will last in exact figures since the system efficiency is a variable factor in every system. That’s why most devices often provide an estimate of remaining running time.

Most smart devices around us give us the remaining charge percentage in the battery. So, if you want to make your battery's application more reliable, the state-of-charge calculation can greatly help you.

Battery State of Charge Formula

The state of charge measures battery charges as you do with a fuel gauge for a fuel tank or laptop battery. It is usually used in percentage terms since much simpler to understand.

The formula for calculating the state of charge for a battery is very simple. It is the current ratio between the total charges inside the battery and the charges your battery can hold at full capacity. So, the state of charge formula looks like this:

SoC = Qt/Qn

Here the variable Qt represents the charges that your battery currently has, while Qn represents the total capacity of your battery to hold charges. 

Remember that you cannot use this formula of state of charge to get accurate measurements under every condition. It is because the working of a battery is a chemical process, and several factors contribute to the system's overall performance.

One of those factors is power efficiency and loss of heat. These can change practical and theoretical values. That’s why the SoC value is often considered an approximate calculation.

Another factor is the difference in the batteries and systems using that battery. Although the SoC measurement done by computers has become nearly accurate, it still needs a lot of development, and that's where battery management systems come in since they communicate every information, including the battery temperature.

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Uses of Using this Formula

There are multiple uses of the state of charge formula. The first one is that you can save the system from unpredictable blockage, which means the batteries will not overcharge. Overcharging batteries damages the system's internal circuitry, which can be prevented with SoC measurement.

Battery State-of-charge Estimator: Using the SVM Technique

SVM is the support vector machine technique that uses supervised learning methods to get an approximate measurement for better accuracy. Measuring the SoC for your battery may not give the most accurate practical results even when, theoretically, those results are 100% true. So, the solution is using the SVM technique since it resolves all the classification problems.

Working on the SVM Technique

This technique of measuring SVM for a battery works by creating a subset of data for training the model. There could be multiple subsets of data from charge cycles, discharge cycles, testing cycles, current, voltage, battery temperature, battery utilization, etc. Hence, the model is trained with almost every possible factor that could be a part of the system.

In that way, the SoC for a battery can be dynamically tested, and the SVM technique generates dynamic values depending on the varying factors that are highly accurate.

The most popular application of SVM battery SoC measurement.

The automobile industry is currently one of the biggest applications of the SVM technique for SoC measurement. Electric vehicles need to give a near-accurate measurement of the remaining time/range for which the batteries can run depending on certain conditions.

While the basic SoC formula neglects every environmental factor, the SVM technique pays attention to all the factors that can be considered, and the level of accuracy is much higher. The best part is a dynamic computation that gives you the right range of information depending on how you are driving the car. It keeps the whole system safe and gives users a better experience with high peace of mind regarding battery reliability.

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Battery State of Charge Percentage

The state of charge formula we discussed above tells the numerical value of the state of charge, which can often be confusing. Taking that measurement in percentage makes things much easier to understand. As it is the level of charge, a battery holds at some given time, when we take that ratio as a percentage, that makes predicting the remaining usability time left for the battery easier.

However, taking the percentage is not difficult as long as you know the implementation of the SoC formula. Take the formula, and at the end of it, multiply the whole value by 100. That will give you the total percentage of the battery's state of charge. For example, if you get 69% as your final answer, the battery currently holds 69 percent of the charge compared to its total capacity.

Technically that means that if a 100mah battery has an SoC of 69%, then it has 69mah capacity still left to power the electronics. Since the total capacity for a battery change, this percentage will also vary with every battery, and so will the time for that battery to power the electronic device.

Benefits of Taking Battery SoC Percentage.

Introducing the SoC percentage for your battery when working on any project has multiple benefits. The top 3 benefits include:

Better Utilization

Knowing the percentage of charges left inside the battery, the energy can be optimally managed, resulting in better utilization. For example, the device may cut unnecessary performance to get a little bit of extra running time.

Efficient Budgeting

Budgeting is essential for bigger power backup units, as you cannot keep the chargers running all day. With the SoC percentage measurement, you know when to provide power and when not, which helps with better budget management.

Conclusion

With state of charge calculation, you can give a specific point of battery capacity at some given time, and it can also be used to tell the percentage of the system. With its benefits, like better battery management, electronics can become smart to utilize batteries with higher efficiency, and that will start making the simple batteries last longer. To calculate the state of charge for your battery, or may utilize the methods and formula discussed above.