What is the State of Health (SOH) Estimation of a Lithium Ion Battery?

In this article, we explain what the state of health (SOH) estimation of a lithium ion battery is and the various methods that can be used to estimate the state of health.

The state of health is an important concept of battery management systems.

The state of health is a measurement which reflects the general condition of a battery and its ability to deliver the specified performance compared with a fresh battery.

The state of health takes into account factors such as the battery's charge acceptance, internal resistance, voltage, and self-discharge.

When a battery is first manufactured, it is described as having 100% health.

Over time, however, there is gradual degradation of the battery, which decreases its state of health over time. The SOH allows us to quantify the battery's health.

Kalman filter and extended Kalman filter are applied to the SOH prediction of batteries by using estimation of the equivalent circuit model.

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