The battery pack of an electrified vehicle isn’t just a fuel tank for its motors. It’s also a metaphorical fuel pump dictating the peak power that can be delivered to a motor. While electric vehicles require both range and power from the battery pack, hybrids require similar power with far less energy. Accordingly, the individual cells are optimized to deliver brief bursts of power in hybrids or long-lasting energy to maximize range for EVs. A plug-in hybrid’s battery pack straddles both priorities and lands somewhere in the middle. A battery’s output-to-storage-capacity ratio (what the industry calls its power-to-energy ratio, or watts per watt-hour) characterizes these differences.