Source: Cleantron

The LEVA-EU member has provided a comprehensive overview of its validated Accurate State of Charge (SoC), an estimate for anticipating the performance, safety, and longevity of lithium-ion batteries. With this feature already being embedded in Cleantron’s BMS platforms, it details the challenges, validation and benefits it offers for OEMs.

For light mobility, industrial batteries, and construction machinery electrified platforms, the SoC has a direct influence on signalling range, peak power delivery, and the risk of misuse.

Cleantron emphasises that a strong SoC reading is a system-level requirement for indicating reliability, safety compliance and commercial viability.

An accurate State of Charge (SoC) estimation is obtained from voltage, current, temperature, and time using model-based algorithms. The SoC indicates how much usable energy remains, when power should be limited and when to proceed with protective actions. An accurate SoC is a quantity that’s not directly measurable.

The implications of an inaccurate SoC for OEMs and end-users

If the SoC is inaccurate for these stakeholders, it could pose risks, including:

• Unexpected shutdown
• Reduction of available power by conservative derating
• Acceleration degradation due to suboptimal charging strategies
• Suboptimal thermal management

Why extreme conditions pose challenges

Cleantron explains that limitations can arise from extreme operating conditions.

• With low temperatures, internal resistance is increased, diffusion dynamics slow down, and open-circuit voltage curves are flattened. These effects decrease observability and amplify errors in estimations.
• At high temperatures, side reactions and nonlinear degradation effects modify cell characteristics in various ways, which static models fail to capture.

Additionally, real-world operating conditions create highly dynamic current patterns. Fast transients, regenerative pulses, and high C-rate discharges lead to voltage polarization and hysteresis, which can distort the perceived State of Charge (SoC). Depth of Discharge (DoD) adds further complexity, as partial cycling differs from full cycling, and degradation mechanisms change depending on the operating range.

Cleantron states that with nonlinear, temperature-dependent, and cycle-dependent factors making SoC estimation challenging, it is important that algorithms stay stable and precise across the whole operational envelope, not just under nominal laboratory conditions.

The significance of validation and how Cleantron ensures it

Due to SoC not being able to be measured directly, its validation is conducted through experimental characterisation.

Cleantron has extensively fine-tuned its battery models with extensive validation across the whole temperature spectrum, with testing carried out at both high and low temperature extremities to monitor resistance shifts, capacity variation, as well as kinetic effects that can impact estimation performance.

Validation also covers various cycling strategies, with real-world drive cycles being used to imitate practical application loads, such as dynamic current profiles that represent end-use environments. Simultaneously, controlled artificial cycles have been applied to pinpoint specific electrochemical behaviours and stress conditions. For these tests, multiple DoD windows were used to verify the accuracy of partial and full cycling regimes.

Cleantron explains that its multi-dimensional dataset has brought a continuous improvement of model parameters, observer tuning, and validation against measurements of ground-truth, resulting in framework which brings a SoC estimation which remains stable, precise, and robust under temperature stress, high dynamics, and long-term cycling.

SoC benefits for OEMs using Cleantron battery systems

With Cleantron’s systems, OEMs can receive validated Accurate State of Charge estimations for predictable performance and reduced integration risk, with reliable range predictions, stable power availability for varied temperatures, and a decreased risk of unexpected shutdown or accelerated degradation.

As its models have been validated and tuned using realistic and worst-case scenarios, its battery system’s behaviour closely equals engineering expectations to reduce calibration effort, decrease development timelines, and optimise confidence for certification and customer use.

Cleantron prides itself on providing SoC validation in helping to ensure its battery packs are dependable energy systems.

How Cleantron supplies the electric vehicle industry

The company is a leading European producer of advanced lithium-ion batteries, which are innovated to provide long-term reliability with captive BMS technology. Its battery technology provides flexibility and dependability to help various company types, including microcars and light electric vehicles, to scale successfully

Its battery portfolio includes a full range of modular batteries, including low and high voltage solutions. As well as standard batteries, Cleantron is specialised in creating tailored battery modules for OEM customers.