Sources of Error with the Coulomb Counting Method

SoC definition for Samsung SDI 94Ah cell

It is really important to understand the sources of error with the coulomb counting method as this forms the backbone for most SOC estimation algorithms. SoC Estimation by Coulomb Counting is based on the measurement of the current and integration of that current over time. There are five main sources of error with the coulomb … Read more

Increasing Usable SoC Window

graph of battery pack usable SoC window percentage versus year of production

If you are in a battery design role there is always pressure on increasing usable SoC window. Nobody wants to pay for and carry around unused battery capacity. However, there are some really good reasons to restrict that window. High SoC and hence high cell voltage stresses the cell and significantly reduces the lifetime. Going … Read more

Usable Energy

In the simplest terms the usable energy of a battery is the Total Energy multiplied by the Usable SoC Window. The total energy is the nominal voltage multiplied by the nominal rated capacity. However, if you have been through the Battery Basics you will have realised that the battery cell and pack do not have … Read more

SoC Estimation by Coulomb Counting

SoC definition

SoC Estimation by Coulomb Counting is based on the measurement of the current and integration of that current over time. The State of Charge (SoC) of a battery cell is required to maintain it’s safe operation and lifetime during charge, discharge and storage. However, SoC cannot be measured directly and is estimated from other measurements and known … Read more

SoC Estimation Techniques

SoC from OCV lookup

There are a number of SoC Estimation Techniques and this article will be just an initial introduction. The State of Charge (SoC) of a battery cell is required to maintain it’s safe operation and lifetime during charge, discharge and storage. However, SoC cannot be measured directly and is estimated from other measurements and known parameters. … Read more