Comparative performance analysis of lead acid and Li-ion batteries of e-bikes used in Sri Lanka

Abstract

The use of electric vehicles is highly popular nowadays. When considering electric vehicles, E-bikes and electric three-wheelers are the most popular in Sri Lanka due to their affordability. Evaluating the performance of E-bikes requires a focus on battery performance. In this research, specific drive cycles were initially analyzed to identify current consumption and speed variations. Using the mean values derived from drive cycle analyzing, battery performance was evaluated. The number of cycles of the battery was considered the primary performance measurement characteristic. Both lead-acid and lithium-ion batteries were tested, with samples representing the maximum and minimum capacities of each type used in E-bikes in the Sri Lankan market. The batteries were discharged under laboratory conditions to 100% Depth of Discharge (DOD), and temperature variations were recorded. Meanwhile, the consumer usage patterns of E-bikes were identified, considering the Asian context. Based on this, the number of cycles for each battery type considering the temperature, was calculated based on daily consumer usage patterns. From this, the replacement time of each battery type and the economic benefit for consumers were calculated. The findings indicate that although lithium-ion batteries have a higher initial cost compared to lead-acid batteries, they offer a longer lifespan, and greater cost-efficiency over time. As a result, lithium-ion batteries were identified as the most suitable option for Sri Lankan E-bike users. This research provides valuable insights for consumers and policymakers to make informed decisions about battery choices for E bikes.