## 1 Introduction  
Portable lighting has gained significant importance for outdoor activities. Recent advancements have led to the widespread adoption of light-emitting diodes (LEDs) in battery-powered systems due to their durability, low power consumption, and reduced environmental impact [1, 2, 3]. These features make LED-based portable lighting a reliable choice for various use cases where energy efficiency and operational autonomy are critical [4]. Studies have shown that battery-powered LED lighting systems can serve various applications effectively, including home lighting, vehicle illumination, signaling systems, and lights powered by building-integrated photovoltaic systems (BIPV) [5, 6]. Therefore, portable lighting systems must have proper design and reliable control mechanisms to comply with outdoor activities [7, 8]. Portable LED systems can be designed to operate on low power, significantly extending battery life, which is essential for applications such as emergency lighting or outdoor activities [9]. However, this solution is not useful because the system must reduce the luminous flux to extend the function, which is not adequate for some outdoor activities. Other authors have proposed the design of portable emergency lamps with solar cells and a rechargeable lithium-ion battery [10]. The proposal used a chip controller in three modes of operation. The first operation is a full bright mode, the second is a medium bright mode, and the third is a flicker mode. Illumination measurements were made showing that the medium bright mode provides an average of 17.58 lux, while the bright mode provides 32.85 lux. However, test results regarding current regulation and lighting were not reported and deviations in intensities are present. In [11], a portable solar lighting system was designed for communities in non-interconnected zones. The system is based on a recycled mixture of polypropylene and polyethylene. They considered only the fixed power supply to obtain an energy autonomy of approximately 4 h. This demonstrated the need for lamps with the highest number of hours of autonomy. Furthermore, the use of intelligent power management systems in portable lighting can optimize energy consumption [8]. For example, systems equipped with microcontrollers can adjust light intensity based on environmental conditions. Hence, they can extend the battery life and improve overall efficiency [12]. Incorporation of visible light communication technologies (VLCs) in these systems can also facilitate energy harvesting and data transmission without the need for batteries, thus further enhancing their sustainability [13]. These are suitable solutions for energy savings, but they do not focus on maintaining a constant luminous flux for portable lighting. An effective method to achieve constant luminous flux output is through adaptive current control systems. By continuously monitoring the light output and adjusting the current supplied to the LEDs, these systems can maintain a stable luminous flux output despite variations in the power supply or battery levels. There are many applications focused on controlling illumination for indoor facilities [8]. Another document presents an investigation into a high-voltage LED controller that improves light efficiency and reduces the complexity of the circuit [14]. Experimental results are introduced to show that compromise compensation and integrated proportional control (PI) maintain the stability of the luminosity despite variations in the input voltage. Thus, the proposed design optimizes the power factor and minimizes energy conversion losses [14]. The development of a portable lighting system that utilizes adaptive current control to maintain constant luminous flux output addresses a significant gap in existing lighting technologies. Although various studies have explored aspects of adaptive lighting systems, there is still a lack of comprehensive solutions specifically designed for portable applications that ensure stable illumination under varying power conditions.