--- title: State of Charge (SoC) description: "State of Charge (SoC) explained: how TWAICE defines and calculates SoC for BESS and how to interpret it in the platform." --- [Skip to content](https://support.twaice.com/knowledge/state-of-charge-soc#main-content) ![TWAICE Help CenterWordmark (2)](https://support.twaice.com/hs-fs/hubfs/Wordmark%20(2).png?width=138&height=28&name=Wordmark%20(2).png) Open main navigation Close main navigation - [Contact us](mailto:support@twaice.com) [Contact us](mailto:support@twaice.com) How can we help you? - There are no suggestions because the search field is empty. 1. [Help Center](https://support.twaice.com/knowledge?hsLang=en) 2. [TWAICE KPIs](https://support.twaice.com/knowledge/twaice-kpis?hsLang=en) # State of Charge (SoC) ## Understand what State of Charge means, how SoC values are determined and how this translates into usable energy in practice. **On this page** - [State of Charge - Definitions and Markers](https://support.twaice.com/knowledge/state-of-charge-soc#h_755e0b9cae) - [How are the State of Charge and State of Health connected?](https://support.twaice.com/knowledge/state-of-charge-soc#h_0054e02ec0) - [How does that translate to batteries?](https://support.twaice.com/knowledge/state-of-charge-soc#h_0712df6463) ### State of Charge - Definitions and Markers You might remember the phrase "fill level may vary due to technical constraints" from grocery shopping. Here, we will show how this challenge also applies to batteries. For the state of charge, it is all about definitions. Looking at the bag in the graph bellow filled with sweets, it is clear that different parties have varying definitions in mind. From the customer perspective, the bag needs to be completely full. From the manufacturer perspective, the bag needs to be empty to a certain extend to ensure a great user experience, but nevertheless, the product is "fully" available for the user. Having different understandings on the definition of "full" leads to misunderstandings, frustrations and errors. The same goes for batteries. [![](https://support.twaice.com/hubfs/Knowledge%20Base%20Import/image-Oct-20-2026-12-28-47-8150-PM.png)](https://downloads.intercomcdn.eu/i/o/19306899/b4c68cb14e4422ea1c991683/image.png?expires=1792501200&signature=ece757ef998df2bf2cf72c3938d72738056b437a1b73ca219c4ee25f87f69938&req=0dxsxV7ypT5k2hL085ZhoT0hJX8bRwfjasJLLmGrVh%2BZDyvD9xexo8484Mxl%0AmyqaH1AjtmUfCasy%0A) The state of charge can be visualized with the filling state of a bottle. The bottle might have some filling indication in ml to indicate how much liquid is inside. Here again, the manufacturer defines a volume, with which the bottle can be filled as full, in the example below this could be the bottle on the left with the blue liquid. If the definition is not shown, the user might have a complete different definition of full and empty, such as the definition which is shown for the bottle on the right side with the green liquid. Both definitions are correct. But if the definitions are not aligned between the people interacting with the bottle, misunderstandings and errors happen. [![](https://support.twaice.com/hubfs/Knowledge%20Base%20Import/image-Oct-20-2026-12-28-50-6830-PM.png)](https://downloads.intercomcdn.eu/i/o/19307108/96718c9e67e53392038d8b10/image.png?expires=1792501200&signature=595f47c4f5d9abd3fed19c652a7d23f96d289ba71d1569c8f089a99ac9913471&req=0dxsxV%2F7rD9k2hL085ZhoX2SWvY%2FdhaJvEcjiSoKLolnWko%2B0D8q1jufy%2FUF%0A6Tk7%2FhQr7F%2BOH6Z9%0A) ### How are the State of Charge and State of Health connected? From the description above, we learned, that the state of charge is about the filling level following a specific definition, the markers in the example here. In the case of the bottle with pre-defined markers to indicate the different filling levels, the **State of Charge answers the question**: How much of the volume is filled? Now, how does the State of Health relate to this? Assuming the bottle with the blue liquid from the example above aged and got damaged to some extend which reduced the diameter. Due to that, the older bottle can only hold a smaller volume of liquid. But the markers on the side of the bottle are still intact to indicate when the bottle is full or empty. The markers hence still indicate when the bottle is full or empty, but the volume of liquid, which can be poured into the bottle is smaller compared to the new bottle. That means, in the example of the bottle, the **State of Health answers the question**: How much volume is available to be filled? [![](https://support.twaice.com/hubfs/Knowledge%20Base%20Import/image-Oct-20-2026-12-29-03-9085-PM.png)](https://downloads.intercomcdn.eu/i/o/19307426/558f8c9ceeef7410b50550bf/image.png?expires=1792501200&signature=7eb99f315353102036e657100162a8d300031f6f15943c33551528b9d8bc30e4&req=0dxsxV%2F%2BrjFk2hL085ZhoavVV2JNB%2FmmOa0iSmwz5EjLQODNKBzeQ1Q%2Fe%2B5A%0AAOZlZUfHhY%2BDts3z%0A) ### How does that translate to batteries? For batteries, we want to understand how much energy (or charge) is at this moment stored inside the battery (this is the State of Charge) and what is the maximum amount of energy (or charge), which can be stored inside the battery (once compared to the initial maximum amount, this is the State of Health). The State of Health is relevant to know, because it determines the maximum amount of energy which can be used to participate in the markets. It impacts the number of hours for which the system can provide the maximum power. The State of Health is dynamic and changes over the lifetime of the system. Due to balancing and maintenance cycles, it can also increase, since energy can be recovered from systems. It has a more long term impact on the daily operation. The State of Charge defines the at this moment still available amount of energy (or charge) in the battery. It is much more relevant for short term operation, since it changes almost every second if the battery is operated. Losing track of the State of Charge can be costly, because the BMS will limit the operation at certain levels to ensure safe operation. But this might result into penalties and lost revenue. © 2026 TWAICE Technologies GmbH [twaice.com](https://www.twaice.com)      [Privacy](https://www.twaice.com/legal/data-protection-notice)      [Imprint](https://www.twaice.com/legal/legal-notice)