New Flash Battery patent: BMS with impedance spectrum for predictive battery management

From impedance spectrum to State of Health

Industrial electrification is entering a new phase: today the focus is no longer only on chemistry or cell format, but on how to manage batteries in an increasingly intelligent, safe and predictive way throughout their entire lifecycle.

It is in this context that our new patent has been developed: “Balancing system for cells of a battery with integrated spectroscopic impedance measurement system”.

It’s a natural evolution of our proprietary BBS balancing system, introducing an advanced feature: measurement of the impedance spectrum of the cells directly within our Battery Management System.

The objective is clear: to gain advanced insights into the battery’s actual condition, improving safety, predictive diagnostics and lifecycle management.

An evolution built on the Flash Balancing System

The starting point is our Flash Balancing System, the technical solution that has defined Flash Battery systems for years.

The first patent, filed a few years after the system was introduced to the market, protects the distinctive architecture our battery BMS is based on:

• Centralised power devices (master)
• Distributed electronics (slave)
• A shared power connection across all cells.

This architecture enables high-power balancing, improving cell uniformity, pack lifespan and overall performance.

The new patent is designed to integrate an advanced measurement capability by leveraging the BMS architecture: the measurement of cell impedance and impedance spectrum.

Impedance: a known parameter, a new challenge

Our CTO, Alan Pastorelli, explains: "Impedance is an electrical parameter, just like voltage and current. Measuring it means quantifying how a cell responds to a variable electrical stimulus."When we talk about impedance spectrum, we mean a series of measurements taken at different frequencies, providing a true “electrical signature” of the cell. This signature changes over time and reflects the internal state of the battery."

The technique is known as EIS - Electrochemical Impedance Spectrum and is widely used in laboratory environments, including outside the battery sector. A well-known example is bioimpedance, used to measure body fat mass.

The real challenge is therefore not the measurement itself, but taking it out of the laboratory and making it:

• Integrable into the BMS
• Reliable in real-world conditions
• Sustainable in terms of cost, size and robustness

And this is precisely where our patent focuses. Why the impedance spectrum is strategic for the BMS

The impedance spectrum is one of the most advanced methods for analysing the internal behaviour of cells. Integrating it directly into the BMS.

Collecting more data to truly understand lithium batteries

Today, all BMSs measure three fundamental parameters:

• Voltage
• Current
• Temperature

These are the minimum requirements to ensure safety and functionality.
However, it’s difficult to get a truly complete picture of the battery’s condition with this information alone.

With this patent, we aim to answer increasingly critical questions for OEMs and users:

• How much useful life does the battery actually have left?
• Is degradation following the expected trend?
• When will replacement need to be scheduled?
• Are there early warning signs of safety risks?

Impedance is one of the most promising parameters to bridge this information gap, as it provides additional data on the internal state of the cells, which can be correlated with key indicators for the end user.

State of Health: how to assess battery lifespan

State of Health (SoH) indicates how much of a battery’s useful life remains.

It’s expressed as a percentage:
100% = new battery
Lower values = progressive degradation over time

In practice, SoH never reaches zero. The battery ceases to be suitable for the application it was designed for much earlier.

A concrete example? The mobile phone we all carry in our pockets: when the battery starts to offer only a few hours of autonomy, we replace it (or change the device altogether).

In the automotive sector, for example, a residual capacity of 80% is often considered the functional end-of-life threshold. In applications such as energy storage, where autonomy is less critical, this threshold can be lower. But it’s not just about identifying a number.

As Alan Pastorelli points out: “The key point is the ability to reliably determine where the battery stands today along its lifecycle”.

This makes it possible to: verify whether actual behaviour is consistent with initial expectations. Estimate remaining life based on real usage. Plan investments and replacements in advance.

In other words, this system enables a shift from a reactive approach to planned battery fleet management.

State of Safety: Anticipating battery risk, not reacting to it

There is another crucial aspect to consider in addition to lifespan: safety.
Continuing to use an exhausted battery makes no sense, either from a performance or a safety perspective.

The goal is to identify when wear may compromise safety as early as possible, enabling preventive action.

In this respect, impedance can become a valuable indicator for building a more advanced State of Safety, capable of detecting weak signals and anticipating potentially critical conditions, thus avoiding unexpected events.

“SoX” indicators for a complete view of battery status

In addition to State of Health and State of Safety, there are several other indicators:

• State of Charge (SoC) → charge level
• State of Power (SoP) → safely available power
• Other “State of X” indicators derived from advanced models

The objective is to build a comprehensive view of battery status, integrating charge, health, safety and power capability, supporting increasingly informed operational and strategic decisions.

The ability to accurately estimate battery State of Health is now one of the main drivers in the development of advanced monitoring and predictive maintenance systems.

Impedance measurement in the BMS: the hardware challenge

The core of the patent lies in the hardware: developing a BMS capable of measuring impedance accurately and repeatably, directly on board the battery.

While this measurement is already possible in laboratory environments, real-world applications introduce stringent constraints:

• Costs
• Space
• Reliability

The difficulty in real applications is further increased because the impedance values to be measured require extremely high sensitivity, particularly given the high capacity of the cells.

The patent focuses precisely on how to leverage the BMS architecture to make this functionality technically and economically viable for real industrial applications.

From laboratory to field: real data for predictive models

Alongside conceptual development, we are already working on experimental testing:

• In the laboratory, by artificially ageing cells and monitoring them over time
• In the field, by analysing batteries operating under particularly demanding conditions

Applications such as those of E80 Group, operating 24/7 and characterised by rapid charging, provide an ideal case: they enable the collection of large volumes of data in shorter timeframes.

Access to data from thousands of connected batteries collected through our Flash Data Center allows us to develop increasingly robust models and validate the correlations between impedance, degradation and safety in the field.

Artificial intelligence and batteries: from data to insight

Measuring impedance is only the first step. State of Health isn’t measured, it’s calculated.

Algorithms, data analysis models and artificial intelligence tools applied to batteries are needed to correlate raw data with reliable indicators.

This activity is part of our internal know-how and is developed both:

• At the embedded level, within the battery
• At cloud/data centre level, leveraging data collected in the field

As clarified by Alan Pastorelli: "AI doesn’t replace engineering, it amplifies its potential, accelerating analysis and progressively improving the accuracy of predictions."

The next generation of battery management: the predictive BMS

The new patent titled "Balancing system for battery cells with an integrated spectroscopic impedance measurement system", already registered in Italy and submitted for European evaluation processes, represents a strategic step for us toward the BMS of the future.

A BMS that doesn’t just monitor instantaneous parameters, but that:

• Interprets the deeper behaviour of the cells
• Anticipates the evolution of their State of Health
• Supports maintenance, investment and lifecycle management decisions

In an increasingly complex industrial electrification landscape, the ability to transform data into predictive insights becomes a key competitive factor for OEMs and system integrators.

Because in today’s industrial electrification – and even more so tomorrow’s – the quality of information is an integral part of performance.