--- title: Detecting Self-Discharge Anomalies description: "Detect self-discharge anomalies in your BESS with TWAICE: how they are identified and what they mean for cell health." --- [Skip to content](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#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) # Detecting Self-Discharge Anomalies ## Understand what self-discharge is, how TWAICE detects abnormal self-discharge in your cells and the logic behind the detection. **On this page** - [What is Self-Discharge?](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#h_8423cbcdae) - [How TWAICE Detects Self-discharge Anomaly](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#h_a3994dbd48) - [Example](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#h_c88ae8ec05) - [Detection Logic](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#h_9fddfbec0c) - [Turning Detection into Action with TWAICE](https://support.twaice.com/knowledge/detecting-self-discharge-anomalies#h_139564788b) ### **What is Self-Discharge?** Self-discharge is a natural phenomenon where cells lose charge even when they are not under load. In large-scale battery energy storage systems, however, abnormally high rates of self-discharge are an **early warning signal of deeper issues**. Typical causes include: - Cell degradation (e.g., lithium plating, electrolyte contamination) or damage - Manufacturing inconsistencies, external or internal defects - Environmental conditions such as high humidity If left unaddressed, abnormal self-discharge can cause both operational and financial damage: - System imbalance and reduced availability, driving up O&M costs - Permanent module damage and accelerated degradation - Lost revenue from downtime and costly replacements ### **How TWAICE Detects Self-discharge Anomaly** The TWAICE platform continuously monitors cell voltages to identify abnormal divergence. An **anomaly** is flagged in the TWAICE **Safety** section when: - The **minimum cell voltage in a string is ≥100 mV lower than that of peer strings** in at least 90% of readings over a sustained period. - **For NMC chemistries**, if this condition lasts less than 5 days, it is marked as "action recommended" (yellow), but if it persists for more than 5 days, it escalates to "action required" (red), as the string may be experiencing ongoing self-discharge and should not simply be recharged without further investigation. The red status remains until the voltage deviation is no longer detected. - In contrast, **for LFP chemistries**, this issue is less critical and always results in "action recommended" (yellow), regardless of the duration. ### Example Let’s investigate an example. Here on **Safety** page, a self-charge issue is flagged for **String 6.1.9** due to low cell voltage value compared to other strings in the same parent. [![](https://support.twaice.com/hubfs/Knowledge%20Base%20Import/Screenshot+2025-10-07+at+16_45_18.png)](https://downloads.intercomcdn.eu/i/o/thagvi83/68422157/de89cfeaf82dafa4dcb295547252/Screenshot+2025-10-07+at+16_45_18.png?expires=1792501200&signature=fd47d50041dc42b5d65c7f029ce5252181c5a1841c0923743dff72d52e15030e&req=1t1rx1r7qTBk2hL085ZhoUEensFt6V82Y%2Fdla3iaD5O33cs0SKmrwThVw2K%2B%0ALCD0P1CBKPcFI45H%0A) We can view the details in Data Explorer: [![](https://support.twaice.com/hubfs/Knowledge%20Base%20Import/Screenshot+2025-10-08+at+13_49_27.png)](https://downloads.intercomcdn.eu/i/o/thagvi83/68422342/a9a027588b2ae735ee793599abbf/Screenshot+2025-10-08+at+13_49_27.png?expires=1792501200&signature=8dcafa4b790eba8088336ceaa03e6e13b5fb67c443bc8d137e0ee1f8bfbea126&req=1t1rx1r5qDVk2hL085ZhoRXI7CXMPAsbiQlhyvNJUVR4EjnC64NZ3ldjQpZW%0AZamDzckt%2BKvklzmI%0A) Most strings remain stable around 3.32 V, while String 6.1.9 (purple) steadily drops to 2.68 V. This persistent voltage gap of over 600 mV clearly indicates abnormal self-discharge and is automatically flagged by the TWAICE platform with recommended actions. The cell voltage above 2.5 V itself is not a safety critical event yet, but the identification of the component via the self-discharge functionality provides an early detection of faulty components. It is therefore a more sophisticated and precise detection method compared to only using static voltage limits. The method cuts through otherwise noise operational data and highlights the relevant insights. ### **Detection Logic** **Why we measure voltage**: - Cell voltage is the most reliable real-time signal for identifying self-discharge. - It directly reflects the state of charge (SoC), and during standby, voltage drift over time becomes the clearest indicator of abnormal behavior. **Relation to self-discharge:** - In a healthy cell, voltage remains stable with only a slow decline. - In a self-discharging cell, however, voltage drops more quickly due to internal side reactions that consume charge. - At the string level, this shows up as a consistently lower minimum cell voltage compared to other strings. **Why compare across strings:** - Since all strings in a system are exposed to the same conditions, comparing them against each other is a robust way to detect anomalies. - A persistent difference of **≥100 mV in at least 90% of readings** between one string and its peers reliably signals abnormal self-discharge. ### **Turning Detection into Action with TWAICE** TWAICE provides a **layer of intelligence on top of BMS data**: - Detects and flags abnormal self-discharge early - Highlights **exactly where and when** the anomaly occurs - Provides **clear recommendations** for preventive actions such as capacity testing or detailed cell-level diagnostics By intervening before failures escalate, operators can avoid costly replacements, downtime, and safety risks — while extending the useful lifetime of their battery assets. © 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)