RACL-B controller: AI that fast-charges EVs 37.9% faster safely

Fast charging is critical for EV adoption, but field chargers typically use a single setting while the cell's true thermal state, ambient temperature, and cooling health are unknown. A current safe for a healthy cell at room temperature can overheat the same cell when it's hot or its cooling is degraded. Yifan Wang's paper on arXiv introduces a margin-aware repair-before-veto controller (RACL-B) that avoids this pitfall. Instead of committing to a fixed schedule or shutting down charging, RACL-B requests an aggressive current and repairs it online to the tightest measured margin among terminal voltage, cell temperature, and negative-electrode lithium-plating overpotential. This allows the charger to dynamically adapt to unknown conditions.

Evaluated using a high-fidelity Doyle–Fuller–Newman model across nine conditions (three ambient temperatures: 10/25/40°C, and three cooling-health levels: 100/60/40%), RACL-B safely completed all cases under a strict 45.0°C peak-temperature audit. In contrast, fixed and ambient-scheduled protocols overheated in five of nine conditions because neither observed hidden cooling degradation, and rigid protective shutdown failed to deliver the charge entirely. RACL-B was 37.9% faster than the fastest fixed current safe across the whole envelope, produced the least plated lithium, and remained safe across thermal guard bands. The same margin-aware principle also powers CREST-B, a transient-credit fault readout that, on a real introduced-fault battery-pack dataset, achieves the strongest learned sequence-to-global monitor for localizing cooling-fault onset under operating-condition shift.