Is your Nissan Leaf’s 40kWh battery showing signs of decay—sluggish charging, reduced range below 250km, or frequent BMS warnings? The 40kWh battery powers 2020-2023 second-gen Leafs (ZE1) and is a popular upgrade for first-gen models seeking more mileage. A Nissan Leaf 40kWh battery swap is the solution to restore performance, but improper execution can damage your EV’s electronics, void warranty, or cause safety hazards. Many owners worry about compatibility, high-voltage risks, or hidden costs. As CNS BATTERY experts, we’ve crafted a step-by-step guide tailored to 40kWh swaps, covering pre-swap checks, tools, installation, and post-swap testing. This guide empowers you to complete a reliable swap—whether DIY with caution or via our certified technicians.