Grid-Scale Second-Life Battery Storage Systems with Distributed Balancing is a grid-focused research and commercialization project that develops a modular, high-voltage energy storage architecture based on second-life EV batteries (SLBs) for reliable operation in hybrid AC/DC smart grids and harsh Canadian climates. The project addresses the three fundamental barriers preventing large-scale SLB deployment—severe module heterogeneity, lack of fault tolerance and hot-swap capability, and poor cold-climate performance—through a patented Modular Battery Equalizer System (MBES) and a novel induced self-heating strategy. MBES enables fully distributed, low-frequency SOC balancing and intrinsic fault isolation without centralized converters, allowing safe operation of mismatched SLBs, online module replacement, and significant lifetime and cost-per-cycle improvements. Complementing this, an AC current–based self-heating mechanism enables uniform, efficient cold starts down to −40 °C without external heaters, dramatically reducing auxiliary power losses and degradation risk. Integrated with grid-supporting inverter platforms and SLB-aware EMS algorithms, the resulting system delivers a scalable, plug-and-play, and certification-ready grid-scale storage solution that directly supports peak shaving, renewable firming, microgrid resiliency, and future hybrid AC/DC grid architectures aligned with the FES “Future Smart Grids Structures” vision.