The Adaptive Backoff Sleep Protocol (ABSP), leveraging the battery discharge curve, is introduced to enhance node scheduling, coverage area, and network lifetime in Heterogeneous Wireless Sensor Networks (HWSNs). ABSP utilizes adaptive node scheduling to accommodate variable load conditions, ensuring that a sufficient number of nodes remain in the ACTIVE state. In contrast, others transition to a low-power SLEEP state. ABSP determines the Backoff Sleep Time (BST) by analyzing the current draw capabilities of the onboard digital modules, tailoring the computation to accommodate the energy profiles of neighboring sleeping nodes. A shunt resistor and ADC converter detect changes in current demand, ensuring the optimal scheduling of the nodes’ duty cycle. ABSP determines the discharge time based on the number of cycles and the duration of variable load conditions in the network, reducing coverage redundancy and extending the network lifetime. Performance evaluations reveal that ABSP surpasses alternative protocols in metrics such as active node count, average energy efficiency, area coverage, and network lifespan up to 400 s, beyond which its performance aligns with that of competing approaches.