State of charge – An important term about battery

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If you are concern about battery performance, then consider gaining knowledge about a few parameters that are directly connected to the battery’ performance and are going to help you with battery development such as SoC ( state of charge ), SoH ( state of health ), SoD ( state of discharge). Here, we are going to learn in detail about state of charge.

What is the meaning of state of charge

State of charge is associated with the quantity of electricity available in the cell for use. It is basically the amount of charge available which is often expressed in percentage to the battery when fully charged.

What is the state of charge of a lithium ion battery

The above graph will show you the different stages of charging a lithium ion battery. Noted that it is not easy to estimate the state of charge of a lithium ion battery because there are many parameters which we have to take into consideration while calculating the state of charge of a battery especially in case of lithium ion battery.

What is the state of charge in BMS

BMS ( battery management system ) usually used in lithium battery packs for residential energy storage systems, power battery system. It can helps us to maintain the battery’s longevity and provide assistance in the development of the battery and its protection. BMS will help us by calculating the state of charge of the battery. It will help the battery to protect itself from overdischarge premature capacity loss and prolong its life. The bms can display the state of charge data of the battery to the user, which is convenient for the user to charge according to the battery condition. And the intelligent function of bms will judge the health status of the battery through the state of charge of the battery during charging and discharging, and prompt the user in time. You can refer to top 10 energy storage BMS manufacturers to get to  know the relevant manufacturers and their multifunctional BMS products.

What is SOC balancing


It is the process in which we equalise the voltage and state of charge for all cells in one battery pack. In practical terms, no two cells are identical, there are always slight differences in the self-discharge rate, capacity, impedance, state of charge, and temperature characteristics.

What is SOC calibration

Calibration of the battery will be done on an auto basis if we use the battery from full to empty (<4%). When we use a battery with charge between 80% and 50%, then your battery forgets when the battery is full or when it is empty, so for better development of a battery you should let your battery go down to 0% once in a month it will help to keep your state of charge in healthy condition. But for lithium-ion batteries, since it has no memory effect, this process is not required. On the contrary, it is beneficial to prolong the life of lithium-ion batteries by charging and using.

How do you measure the state of charge

It is quite difficult to measure the state of charge ( SoC ) of a lithium ion battery unless measured with an instrument. In addition, TYCORUN ENERGY’s energy storage products are equipped with an LCD screen, and the state of charge will be displayed there.

There are few methods by which we can measure the state of charge of batteries such as hydrometer method, voltmeter method, Amp-hour remaining method etc.

Why is the state of charge important

By evaluating the state of charge of a battery, we get a lot of vital information about the battery, such as knowing the remaining power of the battery, charging it in time, and avoiding the battery from over-discharging. In addition, it helps battery manufacturers to improvise and develop the battery. State of charge gives us information about battery performance, battery state etc which will lead us to battery efficient management and better utilisation of battery power and energy.

How do I check the battery state of charge


If you want check the state of charge of the battery such as Powerwall, home power storage, lithium ion golf cart batteries etc then all you have to do is to look for device’s screen and there you get the remaining percentage of battery.

What will be the battery voltage when its SOC is 100 percent

When the state of charge is 100% , then the open circuit voltage of the 51.2v energy storage battery will be 58.4 volts.

What is the difference between SOC and SOE

State of charge indicates the battery state to its charging and discharging when compared to its full charge battery while on the other hand state of energy indicates the energy state in the battery. It is basically relevant to its battery voltage, age etc.

What is the state of charge for a 12v battery

When the state of charge is 100%, the voltage of a 12v battery is 14.6v. When the state of charge is 0, a 12v battery has a voltage of 10v.

Ultimate explanation of basic battery terms besides SOC


Ampere, volt and watt

●Ampere – It is the unit of current. 1 ampere of current is used to denote one coulomb of electric charge moving in one second.

●Voltage – It is the unit of potential difference. 1 volt is used to denote energy consumption of one joule per electric charge of one coulomb.

●Watt – It is the unit of power. 1 watt power is used to denote one joule of work done in one second.

Capacity, circuit, current, cycle

●Capacity – It is basically the total amount of electricity generated due to chemical reactions in the battery.

●Circuit – Circuit is basically the complete path in which electricity can flow.

●Current – Flow of electrons is the most basic and simple definition of current yet it is most accurate.

●Cycle – If we go in terms of battery then one complete charge and discharge of a battery will be considered as one cycle.

Cell and terminals

●Cell – It is the smallest unit of battery.

●Terminals – Terminals are the battery electrical contact point where load is used to connect.

SOH ( state of health )

●SOH – It is the parameter by which we compare the battery parameters at the beginning of life with the current battery condition.

DOD ( depth of discharge )

●DOD – It shows the percentage of battery usable capacity to battery rated capacity.

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