Is your 2021 Nissan Leaf struggling with diminished range, slow charging, or reduced performance in extreme weather? The 2021 Leaf came with two battery options—40kWh (standard) and 62kWh (e+ models)—both engineered to deliver reliable EV performance. But after 5+ years of use, even well-maintained batteries can lose 25-30% of their capacity, turning daily commutes into range-anxious experiences. A step-by-step Nissan Leaf battery upgrade 2021 is the solution, but the model’s active thermal management system and advanced BMS (Battery Management System) demand precision. As CNS BATTERY’s EV experts, we’ve crafted a detailed guide to walk you through the process, from pre-upgrade prep to post-installation testing.